1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
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.
239 <heading>The Debian Archive</heading>
241 The Debian GNU/Linux system is maintained and distributed as a
242 collection of <em>packages</em>. Since there are so many of
243 them (currently well over 6000), they are split into
244 <em>sections</em> and given <em>priorities</em> to simplify
245 the handling of them.
248 The effort of the Debian project is to build a free operating
249 system, but not every package we want to make accessible is
250 <em>free</em> in our sense (see the Debian Free Software
251 Guidelines, below), or may be imported/exported without
252 restrictions. Thus, the archive is split into the sections
253 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
254 <em>non-US/main</em>, <em>non-US/non-free</em>, and
255 <em>non-US/contrib</em>. The sections are explained in detail
260 The <em>main</em> and the <em>non-US/main</em> sections
261 together form the <em>Debian GNU/Linux distribution</em>.
265 Packages in the other sections are not considered to be part
266 of the Debian distribution, although we support their use and
267 provide infrastructure for them (such as our bug-tracking
268 system and mailing lists). This Debian Policy Manual applies
269 to these packages as well.</p>
271 <sect id="pkgcopyright">
272 <heading>Package copyright and sections</heading>
274 The aims of this section are:
276 <list compact="compact">
278 <p>to allow us to make as much software available as we
282 <p>to allow us to encourage everyone to write free
286 <p>to allow us to make it easy for people to produce
287 CD-ROMs of our system without violating any licenses,
288 import/export restrictions, or any other laws.</p>
293 <heading>The Debian Free Software Guidelines</heading>
295 The Debian Free Software Guidelines (DFSG) form our
296 definition of `free software'. These are:
298 <tag>Free Redistribution
302 The license of a Debian component may not restrict any
303 party from selling or giving away the software as a
304 component of an aggregate software distribution
305 containing programs from several different
306 sources. The license may not require a royalty or
307 other fee for such sale.
314 The program must include source code, and must allow
315 distribution in source code as well as compiled form.
322 The license must allow modifications and derived
323 works, and must allow them to be distributed under the
324 same terms as the license of the original software.
327 <tag>Integrity of The Author's Source Code
331 The license may restrict source-code from being
332 distributed in modified form <em>only</em> if the
333 license allows the distribution of ``patch files''
334 with the source code for the purpose of modifying the
335 program at build time. The license must explicitly
336 permit distribution of software built from modified
337 source code. The license may require derived works to
338 carry a different name or version number from the
339 original software. (This is a compromise. The Debian
340 Project encourages all authors to not restrict any
341 files, source or binary, from being modified.)
344 <tag>No Discrimination Against Persons or Groups
348 The license must not discriminate against any person
352 <tag>No Discrimination Against Fields of Endeavor
356 The license must not restrict anyone from making use
357 of the program in a specific field of endeavor. For
358 example, it may not restrict the program from being
359 used in a business, or from being used for genetic
363 <tag>Distribution of License
367 The rights attached to the program must apply to all
368 to whom the program is redistributed without the need
369 for execution of an additional license by those
373 <tag>License Must Not Be Specific to Debian
377 The rights attached to the program must not depend on
378 the program's being part of a Debian system. If the
379 program is extracted from Debian and used or
380 distributed without Debian but otherwise within the
381 terms of the program's license, all parties to whom
382 the program is redistributed must have the same
383 rights as those that are granted in conjunction with
387 <tag>License Must Not Contaminate Other Software
391 The license must not place restrictions on other
392 software that is distributed along with the licensed
393 software. For example, the license must not insist
394 that all other programs distributed on the same medium
395 must be free software.
398 <tag>Example Licenses
402 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
403 examples of licenses that we consider <em>free</em>.
410 <heading>The main section</heading>
412 Every package in <em>main</em> and <em>non-US/main</em>
413 must comply with the DFSG (Debian Free Software
417 In addition, the packages in <em>main</em>
418 <list compact="compact">
421 must not require a package outside of <em>main</em>
422 for compilation or execution (thus, the package must
423 not declare a "Depends", "Recommends", or
424 "Build-Depends" relationship on a non-<em>main</em>
430 must not be so buggy that we refuse to support them,
436 must meet all policy requirements presented in this
443 Similarly, the packages in <em>non-US/main</em>
444 <list compact="compact">
447 must not require a package outside of <em>main</em>
448 or <em>non-US/main</em> for compilation or
454 must not be so buggy that we refuse to support them,
459 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
469 Every package in <em>contrib</em> and
470 <em>non-US/contrib</em> must comply with the DFSG.
474 In addition, the packages in <em>contrib</em> and
475 <em>non-US/contrib</em>
476 <list compact="compact">
479 must not be so buggy that we refuse to support them,
485 must meet all policy requirements presented in this
493 Furthermore, packages in <em>contrib</em> must not require
494 a package in a <em>non-US</em> section for compilation or
499 Examples of packages which would be included in
500 <em>contrib</em> or <em>non-US/contrib</em> are:
501 <list compact="compact">
504 free packages which require <em>contrib</em>,
505 <em>non-free</em> packages or packages which are not
506 in our archive at all for compilation or execution,
512 wrapper packages or other sorts of free accessories for
520 <heading>The non-free section</heading>
522 Packages must be placed in <em>non-free</em> or
523 <em>non-US/non-free</em> if they are not compliant with
524 the DFSG or are encumbered by patents or other legal
525 issues that make their distribution problematic.
528 In addition, the packages in <em>non-free</em> and
529 <em>non-US/non-free</em>
530 <list compact="compact">
533 must not be so buggy that we refuse to support them,
539 must meet all policy requirements presented in this
540 manual that it is possible for them to meet.
543 It is possible that there are policy
544 requirements which the package is unable to
545 meet, for example, if the source is
546 unavailable. These situations will need to be
547 handled on a case-by-case basis.
557 <heading>The non-US sections</heading>
559 Some programs with cryptographic program code need to be
560 stored on the <em>non-US</em> server because of United
561 States export restrictions. Such programs must be
562 distributed in the appropriate <em>non-US</em> section,
563 either <em>non-US/main</em>, <em>non-US/contrib</em> or
564 <em>non-US/non-free</em>.
567 This applies only to packages which contain cryptographic
568 code. A package containing a program with an interface to
569 a cryptographic program or a program that's dynamically
570 linked against a cryptographic library should not be
571 distributed via the <em>non-US</em> server if it is
572 capable of running without the cryptographic library or
577 <heading>Further copyright considerations</heading>
579 Every package must be accompanied by a verbatim copy of
580 its copyright and distribution license in the file
581 <tt>/usr/share/doc/<em><package></em>/copyright</tt>
582 (see <ref id="copyrightfile"> for further details).
585 We reserve the right to restrict files from being included
586 anywhere in our archives if
587 <list compact="compact">
590 their use or distribution would break a law,
595 there is an ethical conflict in their distribution or
601 we would have to sign a license for them, or
606 their distribution would conflict with other project
614 Programs whose authors encourage the user to make
615 donations are fine for the main distribution, provided
616 that the authors do not claim that not donating is
617 immoral, unethical, illegal or something similar; in such
618 a case they must go in <em>non-free</em>.</p>
621 Packages whose copyright permission notices (or patent
622 problems) do not even allow redistribution of binaries
623 only, and where no special permission has been obtained,
624 must not be placed on the Debian FTP site and its mirrors
628 Note that under international copyright law (this applies
629 in the United States, too), <em>no</em> distribution or
630 modification of a work is allowed without an explicit
631 notice saying so. Therefore a program without a copyright
632 notice <em>is</em> copyrighted and you may not do anything
633 to it without risking being sued! Likewise if a program
634 has a copyright notice but no statement saying what is
635 permitted then nothing is permitted.</p>
638 Many authors are unaware of the problems that restrictive
639 copyrights (or lack of copyright notices) can cause for
640 the users of their supposedly-free software. It is often
641 worthwhile contacting such authors diplomatically to ask
642 them to modify their license terms. However, this can be a
643 politically difficult thing to do and you should ask for
644 advice on the <tt>debian-legal</tt> mailing list first, as
649 When in doubt about a copyright, send mail to
650 <email>debian-legal@lists.debian.org</email>. Be prepared
651 to provide us with the copyright statement. Software
652 covered by the GPL, public domain software and BSD-like
653 copyrights are safe; be wary of the phrases `commercial
654 use prohibited' and `distribution restricted'.
658 <heading>Subsections</heading>
661 The packages in the sections <em>main</em>,
662 <em>contrib</em> and <em>non-free</em> are grouped further
663 into <em>subsections</em> to simplify handling.
667 The section and subsection for each package should be
668 specified in the package's <tt>Section</tt> control
669 record. However, the maintainer of the Debian archive
670 may override this selection to ensure the consistency of
671 the Debian distribution. The <tt>Section</tt> field
672 should be of the form:
673 <list compact="compact">
676 <em>subsection</em> if the package is in the
677 <em>main</em> section,
682 <em>section/subsection</em> if the package is in
683 the <em>contrib</em> or <em>non-free</em> section,
689 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
690 <tt>non-US/non-free</tt> if the package is in
691 <em>non-US/main</em>, <em>non-US/contrib</em> or
692 <em>non-US/non-free</em> respectively.
699 The Debian archive maintainers provide the authoritative
700 list of subsections. At present, they are:
701 <em>admin</em>, <em>base</em>, <em>comm</em>,
702 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
703 <em>editors</em>, <em>electronics</em>, <em>games</em>,
704 <em>graphics</em>, <em>hamradio</em>,
705 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
706 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
707 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
708 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
709 <em>sound</em>, <em>tex</em>, <em>text</em>,
710 <em>utils</em>, <em>web</em>, <em>x11</em>.
714 <heading>Priorities</heading>
717 Each package should have a <em>priority</em> value, which is
718 included in the package's <em>control record</em>. This
719 information is used by the Debian package management tools
720 to separate high-priority packages from less-important
724 The following <em>priority levels</em> are recognised by the
725 Debian package management tools.
727 <tag><tt>required</tt></tag>
730 Packages which are necessary for the proper
731 functioning of the system. You must not remove these
732 packages or your system may become totally broken and
733 you may not even be able to use <prgn>dpkg</prgn> to
734 put things back. Systems with only the
735 <tt>required</tt> packages are probably unusable, but
736 they do have enough functionality to allow the
737 sysadmin to boot and install more software.</p>
739 <tag><tt>important</tt></tag>
742 Important programs, including those which one would
743 expect to find on any Unix-like system. If the
744 expectation is that an experienced Unix person who
745 found it missing would say `What on earth is going on,
746 where is <prgn>foo</prgn>?', it must be an
747 <tt>important</tt> package.
750 This is an important criterion because we are
751 trying to produce, amongst other things, a free
755 Other packages without which the system will not run
756 well or be usable must also have priority
757 <tt>important</tt>. This does
758 <em>not</em> include Emacs, the X Window System, TeX
759 or any other large applications. The
760 <tt>important</tt> packages are just a bare minimum of
761 commonly-expected and necessary tools.</p>
763 <tag><tt>standard</tt></tag>
766 These packages provide a reasonably small but not too
767 limited character-mode system. This is what will be
768 installed by default if the user doesn't select anything
769 else. It doesn't include many large applications, but
770 it does include Emacs (this is more of a piece of
771 infrastructure than an application) and a reasonable
772 subset of TeX and LaTeX.</p>
774 <tag><tt>optional</tt></tag>
777 (In a sense everything that isn't required is
778 optional, but that's not what is meant here.) This is
779 all the software that you might reasonably want to
780 install if you didn't know what it was and don't have
781 specialized requirements. This is a much larger system
782 and includes the X Window System, a full TeX
783 distribution, and many applications. Note that
784 optional packages should not conflict with each other.
787 <tag><tt>extra</tt></tag>
790 This contains all packages that conflict with others
791 with required, important, standard or optional
792 priorities, or are only likely to be useful if you
793 already know what they are or have specialised
800 Packages must not depend on packages with lower priority
801 values (excluding build-time dependencies). In order to
802 ensure this, the priorities of one or more packages may need
808 <heading>Binary packages</heading>
811 The Debian GNU/Linux distribution is based on the Debian
812 package management system, called <prgn>dpkg</prgn>. Thus,
813 all packages in the Debian distribution must be provided
814 in the <tt>.deb</tt> file format.</p>
818 <heading>The package name</heading>
821 Every package must have a name that's unique within the Debian
825 Package names must consist of lower case letters (a-z),
826 digits (0-9), plus (+) and minus (-) signs, and periods
827 (.). They must be at least two characters long and must
828 contain at least one letter.
832 The package name is part of the file name of the
833 <tt>.deb</tt> file and is included in the control field
839 <heading>The maintainer of a package</heading>
841 Every package must have a Debian maintainer (the
842 maintainer may be one person or a group of people
843 reachable from a common email address, such as a mailing
844 list). The maintainer is responsible for ensuring that
845 the package is placed in the appropriate distributions.
849 The maintainer must be specified in the
850 <tt>Maintainer</tt> control field with their correct name
851 and a working email address. If one person maintains
852 several packages, he/she should try to avoid having
853 different forms of their name and email address in
854 the <tt>Maintainer</tt> fields of those packages.
858 If the maintainer of a package quits from the Debian
859 project, "Debian QA Group"
860 <email>packages@qa.debian.org</email> takes over the
861 maintainership of the package until someone else
862 volunteers for that task. These packages are called
863 <em>orphaned packages</em>.
866 The detailed procedure for doing this gracefully can
867 be found in the Debian Developer's Reference, either
868 in the <tt>developers-reference</tt> package, or on
869 the Debian FTP server
870 <ftpsite>ftp.debian.org</ftpsite> as
871 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
873 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
874 name="Debian Developer's Reference"> webpage.
882 <heading>The description of a package</heading>
885 Every Debian package must have an extended description
886 stored in the appropriate field of the control record.</p>
889 The description should be written so that it gives the
890 system administrator enough information to decide whether
891 to install the package. This description should not just
892 be copied verbatim from the program's documentation.
893 Instructions for configuring or using the package should
894 not be included -- that is what installation scripts,
895 manual pages, info files, etc., are for. Copyright
896 statements and other administrivia should not be included
897 either -- that is what the copyright file is for.</p>
902 <heading>Dependencies</heading>
905 Every package must specify the dependency information
906 about other packages that are required for the first to
910 For example, a dependency entry must be provided for any
911 shared libraries required by a dynamically-linked executable
912 binary in a package.</p>
915 Packages are not required to declare any dependencies they
916 have on other packages which are marked <tt>Essential</tt>
917 (see below), and should not do so unless they depend on a
918 particular version of that package.</p>
921 Sometimes, a package requires another package to be installed
922 <em>and</em> configured before it can be installed. In this
923 case, you must specify a <tt>Pre-Depends</tt> entry for
927 You should not specify a <tt>Pre-Depends</tt> entry for a
928 package before this has been discussed on the
929 <tt>debian-devel</tt> mailing list and a consensus about
930 doing that has been reached.</p></sect1>
934 <heading>Virtual packages</heading>
937 Sometimes, there are several packages which offer
938 more-or-less the same functionality. In this case, it's
939 useful to define a <em>virtual package</em> whose name
940 describes that common functionality. (The virtual
941 packages only exist logically, not physically--that's why
942 they are called <em>virtual</em>.) The packages with this
943 particular function will then <em>provide</em> the virtual
944 package. Thus, any other package requiring that function
945 can simply depend on the virtual package without having to
946 specify all possible packages individually.</p>
949 All packages should use virtual package names where
950 appropriate, and arrange to create new ones if necessary.
951 They should not use virtual package names (except privately,
952 amongst a cooperating group of packages) unless they have
953 been agreed upon and appear in the list of virtual package
957 The latest version of the authoritative list of virtual
958 package names can be found on
959 <ftpsite>ftp.debian.org</ftpsite> in
960 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
961 or your local mirror. In addition, it is included in the
962 <tt>debian-policy</tt> package. The procedure for updating
963 the list is described at the top of the file.</p></sect1>
967 <heading>Base packages</heading>
970 The packages included in the <tt>base</tt> section have a
971 special function. They form a minimum subset of the Debian
972 GNU/Linux system that is installed before everything else
973 on a new system. Thus, only very few packages are allowed
974 to go into the <tt>base</tt> section to keep the required
975 disk usage very small.</p>
978 Most of these packages will have the priority value
979 <tt>required</tt> or at least <tt>important</tt>, and many
980 of them will be tagged <tt>essential</tt> (see below).</p>
983 You must not place any packages into the <tt>base</tt>
984 section before this has been discussed on the
985 <tt>debian-devel</tt> mailing list and a consensus about
986 doing that has been reached.</p></sect1>
990 <heading>Essential packages</heading>
993 Some packages are tagged <tt>essential</tt>. (They have
994 <tt>Essential: yes</tt> in their package control record.)
995 This flag is used for packages that are <em>essential</em>
999 Since these packages cannot be easily removed (one has to
1000 specify an extra <em>force option</em> to
1001 <prgn>dpkg</prgn> to do so), this flag must not be used
1002 unless absolutely necessary. A shared library package
1003 must not be tagged <tt>essential</tt>--dependencies will
1004 prevent its premature removal, and we need to be able to
1005 remove it when it has been superseded.
1009 Since dpkg will not prevent upgrading of other packages
1010 while an <tt>essential</tt> package is in an unconfigured
1011 state, all <tt>essential</tt> packages must supply all of
1012 their core functionality even when unconfigured. If the
1013 package cannot satisfy this requirement it must not be
1014 tagged as essential, and any packages depending on this
1015 package must instead have explicit dependency fields as
1020 You must not tag any packages <tt>essential</tt> before
1021 this has been discussed on the <tt>debian-devel</tt>
1022 mailing list and a consensus about doing that has been
1028 <heading>Maintainer scripts</heading>
1031 The package installation scripts should avoid producing
1032 output which it is unnecessary for the user to see and
1033 should rely on <prgn>dpkg</prgn> to stave off boredom on
1034 the part of a user installing many packages. This means,
1035 amongst other things, using the <tt>--quiet</tt> option on
1036 <prgn>install-info</prgn>.</p>
1039 Errors which occur during the execution of an installation
1040 script must be checked and the installation must not
1041 continue after an error.
1045 Note that in general <ref id="scripts"> applies to package
1046 maintainer scripts, too.
1050 You should not use <tt>dpkg-divert</tt> on a file
1051 belonging to another package without consulting the
1052 maintainer of that package first.
1055 All packages which supply an instance of a common command
1056 name (or, in general, filename) should generally use
1057 <prgn>update-alternatives</prgn>, so that they may be
1058 installed together. If <prgn>update-alternatives</prgn>
1059 is not used, then each package must use
1060 <var>Conflicts</var> to ensure that other packages are
1061 de-installed. (In this case, it may be appropriate to
1062 specify a conflict against earlier versions of something
1063 that previously did not use
1064 <prgn>update-alternatives</prgn> - this is an exception to
1065 the usual rule that versioned conflicts should be
1071 <heading>Prompting in maintainer scripts</heading>
1073 Package maintainer scripts may prompt the user if
1074 necessary. Prompting may be accomplished by hand, or by
1075 communicating with a program, such as
1076 <prgn>debconf</prgn>, which conforms to the Debian
1077 Configuration management specification, version 2 or
1078 higher. These are included in the
1079 <file>debconf_specification</file> files in the
1080 <package>debian-policy</package> package.
1081 You may also find this file on the FTP site
1082 <ftpsite>ftp.debian.org</ftpsite> in
1083 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1084 or on your local mirror.
1087 2.5% of Debian packages [see <url
1088 id="http://kitenet.net/programs/debconf/stats/">]
1089 currently use <package>debconf</package> to prompt
1090 the user at install time, and this number is growing
1091 daily. The benefits of using debconf are briefly
1093 id="http://kitenet.net/doc/debconf-doc/introduction.html">;
1094 they include preconfiguration, (mostly)
1095 noninteractive installation, elimination of
1096 redundant prompting, consistency of user interface,
1100 With this increasing number of packages using
1101 <package>debconf</package>, plus the existance of a
1102 nascent second implementation of the Debian
1103 configuration management system
1104 (<package>cdebconf</package>), and the stabalization
1105 of the protocol these things use, the time has
1106 finally come to reflect the use of these things in
1113 Packages which use the Debian Configuration management
1114 specification may contain an additional
1115 <file>config</file> script and a <file>templates</file>
1116 file in their control archive. The <prgn>config</prgn>
1117 script might be run before the <prgn>preinst</prgn>
1118 script, and before the package is unpacked or any of its
1119 dependancies or pre-dependancies are satisfied.
1120 Therefore it must work using only the tools present in
1121 <em>essential</em> packages.
1124 <package>Debconf</package> or another tool that
1125 implements the Debian Configuration management
1126 specification will also be installed, and any
1127 versioned dependencies on it will be satisfied
1128 before preconfiguration begins.
1134 Packages should try to minimize the amount of prompting
1135 they need to do, and they should ensure that the user
1136 will only ever be asked each question once. This means
1137 that packages should try to use appropriate shared
1138 configuration files (such as <tt>/etc/papersize</tt> and
1139 <tt>/etc/news/server</tt>), and shared
1140 <package>debconf</package> variables rather than each
1141 prompting for their own list of required pieces of
1146 It also means that an upgrade should not ask the same
1147 questions again, unless the user has used <tt>dpkg
1148 --purge</tt> to remove the package's configuration. The
1149 answers to configuration questions should be stored in an
1150 appropriate place in <tt>/etc</tt> so that the user can
1151 modify them, and how this has been done should be
1155 If a package has a vitally important piece of
1156 information to pass to the user (such as "don't run me
1157 as I am, you must edit the following configuration files
1158 first or you risk your system emitting badly-formatted
1159 messages"), it should display this in the
1160 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1161 prompt the user to hit return to acknowledge the
1162 message. Copyright messages do not count as vitally
1163 important (they belong in
1164 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1165 neither do instructions on how to use a program (these
1166 should be in on-line documentation, where all the users
1170 Any necessary prompting should almost always be confined
1171 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1172 script. If it is done in the <prgn>postinst</prgn>, it
1173 should be protected with a conditional so that unnecessary
1174 prompting doesn't happen if a package's installation fails
1175 and the <prgn>postinst</prgn> is called with
1176 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1177 <tt>abort-deconfigure</tt>.</p>
1182 <heading>Source packages</heading>
1184 <sect1 id="standardsversion">
1185 <heading>Standards conformance</heading>
1188 In the source package's <tt>Standards-Version</tt> control
1189 field, you must specify the most recent version number of
1190 this policy document with which your package complies.
1191 The current version number is &version;.
1195 This information may be used to file bug reports
1196 automatically if your package becomes too much out of
1201 The version number has four components--major and minor
1202 version number and major and minor patch level. When the
1203 standards change in a way that requires every package to
1204 change the major number will be changed. Significant
1205 changes that will require work in many packages will be
1206 signaled by a change to the minor number. The major patch
1207 level will be changed for any change to the meaning of the
1208 standards, however small; the minor patch level will be
1209 changed when only cosmetic, typographical or other edits
1210 are made which neither change the meaning of the document
1211 nor affect the contents of packages.</p>
1214 Thus only the first three components of the policy version
1215 are significant in the <em>Standards-Version</em> control
1216 field, and so either these three components or the all
1217 four components may be specified.
1220 In the past, people specified the full version number
1221 in the Standards-Version field, for example `2.3.0.0'.
1222 Since minor patch-level changes don't introduce new
1223 policy, it was thought it would be better to relax
1224 policy and only require the first 3 components to be
1225 specified, in this example `2.3.0'. All four
1226 components may still be used if someone wishes to do
1233 You should regularly, and especially if your package has
1234 become out of date, check for the newest Policy Manual
1235 available and update your package, if necessary. When your
1236 package complies with the new standards you should update the
1237 <tt>Standards-Version</tt> source package field and
1241 See the file <tt>upgrading-checklist</tt> for
1242 information about policy which has changed between
1243 different versions of this document.
1251 <heading>Package relationships</heading>
1254 Source packages should specify which binary packages they
1255 require to be installed or not to be installed in order to
1256 build correctly. For example, if building a package
1257 requires a certain compiler, then the compiler should be
1258 specified as a build-time dependency.
1262 It is not necessary to explicitly specify build-time
1263 relationships on a minimal set of packages that are always
1264 needed to compile, link and put in a Debian package a
1265 standard "Hello World!" program written in C or C++. The
1266 required packages are called <em>build-essential</em>, and
1267 an informational list can be found in
1268 <tt>/usr/share/doc/build-essential/list</tt> (which is
1269 contained in the <tt>build-essential</tt>
1275 <p>This allows maintaining the list separately
1276 from the policy documents (the list does not
1277 need the kind of control that the policy
1283 Having a separate package allows one to install
1284 the build-essential packages on a machine, as
1285 well as allowing other packages such as task
1286 packages to require installation of the
1287 build-essential packages using the depends
1293 The separate package allows bug reports against
1294 the list to be categorized separately from
1295 the policy management process in the BTS.
1305 When specifying the set of build-time dependencies, one
1306 should list only those packages explicitly required by the
1307 build. It is not necessary to list packages which are
1308 required merely because some other package in the list of
1309 build-time dependencies depends on them.
1312 The reason for this is that dependencies change, and
1313 you should list all those packages, and <em>only</em>
1314 those packages that <em>you</em> need directly. What
1315 others need is their business. For example, if you
1316 only link against <tt>libimlib</tt>, you will need to
1317 build-depend on <package>libimlib2-dev</package> but
1318 not against any <tt>libjpeg*</tt> packages, even
1319 though <tt>libimlib2-dev</tt> currently depends on
1320 them: installation of <package>libimlib2-dev</package>
1321 will automatically ensure that all of its run-time
1322 dependencies are satisfied.
1328 If build-time dependencies are specified, it must be
1329 possible to build the package and produce working binaries
1330 on a system with only essential and build-essential
1331 packages installed and also those required to satisfy the
1332 build-time relationships (including any implied
1333 relationships). In particular, this means that version
1334 clauses should be used rigorously in build-time
1335 relationships so that one cannot produce bad or
1336 inconsistently configured packages when the relationships
1337 are properly satisfied.
1341 <heading>Changes to the upstream sources</heading>
1344 If changes to the source code are made that are not
1345 specific to the needs of the Debian system, they should be
1346 sent to the upstream authors in whatever form they prefer
1347 so as to be included in the upstream version of the
1351 If you need to configure the package differently for
1352 Debian or for Linux, and the upstream source doesn't
1353 provide a way to do so, you should add such configuration
1354 facilities (for example, a new <prgn>autoconf</prgn> test
1355 or <tt>#define</tt>) and send the patch to the upstream
1356 authors, with the default set to the way they originally
1357 had it. You can then easily override the default in your
1358 <tt>debian/rules</tt> or wherever is appropriate.</p>
1361 You should make sure that the <prgn>configure</prgn> utility
1362 detects the correct architecture specification string
1363 (refer to <ref id="arch-spec"> for details).</p>
1366 If you need to edit a <prgn>Makefile</prgn> where
1367 GNU-style <prgn>configure</prgn> scripts are used, you
1368 should edit the <tt>.in</tt> files rather than editing the
1369 <prgn>Makefile</prgn> directly. This allows the user to
1370 reconfigure the package if necessary. You should
1371 <em>not</em> configure the package and edit the generated
1372 <prgn>Makefile</prgn>! This makes it impossible for
1373 someone else to later reconfigure the package.</p></sect1>
1377 <heading>Documenting your changes</heading>
1380 You should document your changes and updates to the source
1381 package properly in the <tt>debian/changelog</tt> file. (Note
1382 that mistakes in changelogs are usually best rectified by
1383 making a new changelog entry rather than "rewriting history"
1384 by editing old changelog entries.)</p>
1387 In non-experimental packages you must use a format for
1388 <tt>debian/changelog</tt> which is supported by the most
1389 recent released version of <prgn>dpkg</prgn>.
1392 If you wish to use an alternative format, you may do
1393 so as long as you include a parser for it in your
1394 source package. The parser must have an API
1395 compatible with that expected by
1396 <prgn>dpkg-genchanges</prgn> and
1397 <prgn>dpkg-gencontrol</prgn>. If there is general
1398 interest in the new format, you should contact the
1399 <package>dpkg</package> maintainer to have the parser
1400 script for it included in the <prgn>dpkg</prgn>
1401 package. (You will need to agree that the parser and
1402 its manpage may be distributed under the GNU GPL, just
1403 as the rest of `dpkg' is.)
1411 <heading>Error trapping in makefiles</heading>
1414 When <prgn>make</prgn> invokes a command in a makefile
1415 (including your package's upstream makefiles and
1416 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1417 means that <tt>sh</tt>'s usual bad error handling
1418 properties apply: if you include a miniature script as one
1419 of the commands in your makefile you'll find that if you
1420 don't do anything about it then errors are not detected
1421 and <prgn>make</prgn> will blithely continue after
1425 Every time you put more than one shell command (this
1426 includes using a loop) in a makefile command you
1427 must make sure that errors are trapped. For
1428 simple compound commands, such as changing directory and
1429 then running a program, using <tt>&&</tt> rather
1430 than semicolon as a command separator is sufficient. For
1431 more complex commands including most loops and
1432 conditionals you should include a separate <tt>set -e</tt>
1433 command at the start of every makefile command that's
1434 actually one of these miniature shell scripts.</p></sect1>
1438 <heading>Obsolete constructs and libraries</heading>
1441 The include file <prgn><varargs.h></prgn> is
1442 provided to support end-users compiling very old software;
1443 the library <tt>libtermcap</tt> is provided to support the
1444 execution of software which has been linked against it
1445 (either old programs or those such as Netscape which are
1446 only available in binary form).</p>
1449 Debian packages should be patched to use
1450 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1457 <chapt id="controlfields"><heading>Control files and their fields</heading>
1460 Many of the tools in the package management suite manipulate
1461 data represented in a common format, known as <em>control
1462 data</em>. The data is often stored in <em>control
1463 files</em>. Binary and source packages have control files,
1464 and the <tt>.changes</tt> files which control the installation
1465 of uploaded files are also in control file format.
1466 <prgn>Dpkg</prgn>'s internal databases are in a similar
1470 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1473 A control file consists of one or more paragraphs of fields.
1474 The paragraphs are separated by blank lines. Some control
1475 files allow only one paragraph; others allow several, in
1476 which case each paragraph usually refers to a different
1477 package. (For example, in source packages, the first
1478 paragraph refers to the source package, and later paragraphs
1479 refer to binary packages generated from the source.)
1483 Each paragraph consists of a series of data fields; each
1484 field consists of the field name, followed by a colon and
1485 then the data/value associated with that field. It ends at
1486 the end of the line. Horizontal whitespace (spaces and
1487 tabs) may occur immediately before or after the value and is
1488 ignored there; it is conventional to put a single space
1489 after the colon. For example, a field might be:
1493 the field name is <tt>Package</tt> and the field value
1498 Some fields' values may span several lines; in this case
1499 each continuation line <em>must</em> start with a space or
1500 tab. Any trailing spaces or tabs at the end of individual
1501 lines of a field value are ignored.
1505 Except where otherwise stated only a single line of data is
1506 allowed and whitespace is not significant in a field body.
1507 Whitespace must not appear inside names (of packages,
1508 architectures, files or anything else) or version numbers,
1509 or between the characters of multi-character version
1514 Field names are not case-sensitive, but it is usual to
1515 capitalize the field names using mixed case as shown below.
1519 Blank lines, or lines consisting only of spaces and tabs,
1520 are not allowed within field values or between fields - that
1521 would mean a new paragraph.
1526 <sect><heading>List of fields</heading>
1528 This list here is not supposed to be exhaustive. Most fields
1529 are dealt with elsewhere in this document.
1531 <sect1 id="f-Package"><heading><tt>Package</tt>
1535 The name of the binary package. Package names consist of
1536 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1537 (plus, minus and full stop).
1541 They must be at least two characters long and must start
1542 with an alphanumeric character and not be all digits. The
1543 use of lowercase package names is strongly recommended
1544 unless the package you're building (or referring to, in
1545 other fields) is already using uppercase.</p>
1548 <sect1 id="f-Version"><heading><tt>Version</tt>
1552 This lists the source or binary package's version number -
1553 see <ref id="versions">.
1559 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1563 The most recent version of the standards (the policy
1564 manual and associated texts) with which the package
1565 complies. This is updated manually when editing the
1566 source package to conform to newer standards; it can
1567 sometimes be used to tell when a package needs attention.
1568 Its format is described above; see
1569 <ref id="standardsversion">.
1574 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1578 In a <tt>.changes</tt> file or parsed changelog output
1579 this contains the (space-separated) name(s) of the
1580 distribution(s) where this version of the package should
1581 be installed. Valid distributions are determined by the
1582 archive maintainers.
1584 Current distribution names are:
1586 <tag><em>stable</em></tag>
1589 This is the current `released' version of Debian
1590 GNU/Linux. Once the distribution is
1591 <em>stable</em> only security fixes and other
1592 major bug fixes are allowed. When changes are
1593 made to this distribution, the release number is
1594 increased (for example: 2.2r1 becomes 2.2r2 then
1599 <tag><em>unstable</em></tag>
1602 This distribution value refers to the
1603 <em>developmental</em> part of the Debian
1604 distribution tree. New packages, new upstream
1605 versions of packages and bug fixes go into the
1606 <em>unstable</em> directory tree. Download from
1607 this distribution at your own risk.
1611 <tag><em>testing</em></tag>
1614 This distribution value refers to the
1615 <em>testing</em> part of the Debian distribution
1616 tree. It receives its packages from the
1617 unstable distribution after a short time lag to
1618 ensure that there are no major issues with the
1619 unstable packages. It is less prone to breakage
1620 than unstable, but still risky. It is not
1621 possible to upload packages directly to
1626 <tag><em>frozen</em></tag>
1629 From time to time, the <em>frozen</em>
1630 distribution enters a state of `code-freeze' in
1631 anticipation of release as a <em>stable</em>
1632 version. During this period of testing only
1633 fixes for existing or newly-discovered bugs will
1634 be allowed. The exact details of this stage are
1635 determined by the Release Manager.
1639 <tag><em>experimental</em></tag>
1642 The packages with this distribution value are
1643 deemed by their maintainers to be high
1644 risk. Oftentimes they represent early beta or
1645 developmental packages from various sources that
1646 the maintainers want people to try, but are not
1647 ready to be a part of the other parts of the
1648 Debian distribution tree. Download at your own
1654 You should list <em>all</em> distributions that the
1655 package should be installed into.
1664 <chapt id="versions"><heading>Version numbering</heading>
1667 Every package has a version number recorded in its
1668 <tt>Version</tt> control file field.
1672 The package management system imposes an ordering on version
1673 numbers, so that it can tell whether packages are being up- or
1674 downgraded and so that package system front end applications
1675 can tell whether a package it finds available is newer than
1676 the one installed on the system. The version number format
1677 has the most significant parts (as far as comparison is
1678 concerned) at the beginning.
1682 The version number format is:
1683 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1687 The three components here are:
1689 <tag><var>epoch</var></tag>
1693 This is a single (generally small) unsigned integer. It
1694 may be omitted, in which case zero is assumed. If it is
1695 omitted then the <var>upstream_version</var> may not
1700 It is provided to allow mistakes in the version numbers
1701 of older versions of a package, and also a package's
1702 previous version numbering schemes, to be left behind.
1707 <tag><var>upstream_version</var></tag>
1711 This is the main part of the version number. It is
1712 usually the version number of the original (`upstream')
1713 package from which the <tt>.deb</tt> file has been made,
1714 if this is applicable. Usually this will be in the same
1715 format as that specified by the upstream author(s);
1716 however, it may need to be reformatted to fit into the
1717 package management system's format and comparison
1722 The comparison behavior of the package management system
1723 with respect to the <var>upstream_version</var> is
1724 described below. The <var>upstream_version</var>
1725 portion of the version number is mandatory.
1729 The <var>upstream_version</var> may contain only
1732 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1734 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1735 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1736 start with a digit. If there is no
1737 <var>debian_revision</var> then hyphens are not allowed;
1738 if there is no <var>epoch</var> then colons are not
1742 <tag><var>debian_revision</var></tag>
1746 This part of the version number specifies the version of
1747 the Debian package based on the upstream version. It
1748 may contain only alphanumerics and the characters
1749 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1750 compared in the same way as the
1751 <var>upstream_version</var> is.
1755 It is optional; if it isn't present then the
1756 <var>upstream_version</var> may not contain a hyphen.
1757 This format represents the case where a piece of
1758 software was written specifically to be turned into a
1759 Debian package, and so there is only one `debianization'
1760 of it and therefore no revision indication is required.
1764 It is conventional to restart the
1765 <var>debian_revision</var> at <tt>1</tt> each time the
1766 <var>upstream_version</var> is increased.
1770 The package management system will break the version
1771 number apart at the last hyphen in the string (if there
1772 is one) to determine the <var>upstream_version</var> and
1773 <var>debian_revision</var>. The absence of a
1774 <var>debian_revision</var> compares earlier than the
1775 presence of one (but note that the
1776 <var>debian_revision</var> is the least significant part
1777 of the version number).
1781 The <var>upstream_version</var> and <var>debian_revision</var>
1782 parts are compared by the package management system using the
1787 The strings are compared from left to right.
1791 First the initial part of each string consisting entirely of
1792 non-digit characters is determined. These two parts (one of
1793 which may be empty) are compared lexically. If a difference
1794 is found it is returned. The lexical comparison is a
1795 comparison of ASCII values modified so that all the letters
1796 sort earlier than all the non-letters.
1800 Then the initial part of the remainder of each string which
1801 consists entirely of digit characters is determined. The
1802 numerical values of these two parts are compared, and any
1803 difference found is returned as the result of the comparison.
1804 For these purposes an empty string (which can only occur at
1805 the end of one or both version strings being compared) counts
1810 These two steps (comparing and removing initial non-digit
1811 strings and initial digit strings) are repeated until a
1812 difference is found or both strings are exhausted.
1816 Note that the purpose of epochs is to allow us to leave behind
1817 mistakes in version numbering, and to cope with situations
1818 where the version numbering scheme changes. It is
1819 <em>not</em> intended to cope with version numbers containing
1820 strings of letters which the package management system cannot
1821 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1822 silly orderings (the author of this manual has heard of a
1823 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1824 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1825 <tt>2</tt> and so forth).
1829 If an upstream package has problematic version numbers they
1830 should be converted to a sane form for use in the
1831 <tt>Version</tt> field.
1835 <heading>Version numbers based on dates</heading>
1837 In general, Debian packages should use the same version
1838 numbers as the upstream sources.</p>
1841 However, in some cases where the upstream version number is
1842 based on a date (e.g., a development `snapshot' release) the
1843 package management system cannot handle these version
1844 numbers without epochs. For example, dpkg will consider
1845 `96May01' to be greater than `96Dec24'.</p>
1848 To prevent having to use epochs for every new upstream
1849 version, the version number should be changed to the
1850 following format in such cases: `19960501', `19961224'. It
1851 is up to the maintainer whether he/she wants to bother the
1852 upstream maintainer to change the version numbers upstream,
1856 Note that other version formats based on dates which are
1857 parsed correctly by the package management system should
1858 <em>not</em> be changed.</p>
1861 Native Debian packages (i.e., packages which have been
1862 written especially for Debian) whose version numbers include
1863 dates should always use the `YYYYMMDD' format.</p>
1867 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1869 <sect id="timestamps"><heading>Time Stamps</heading>
1871 Maintainers should preserve the modification times of the
1872 upstream source files in a package, as far as is reasonably
1876 The rationale is that there is some information conveyed
1877 by knowing the age of the file, for example, you could
1878 recognize that some documentation is very old by looking
1879 at the modification time, so it would be nice if the
1880 modification time of the upstream source would be
1887 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1888 main building script</heading>
1891 This file must be an executable makefile, and contains the
1892 package-specific recipes for compiling the package and
1893 building binary package(s) from the source.
1897 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1898 so that it can be invoked by saying its name rather than
1899 invoking <prgn>make</prgn> explicitly.
1903 Since an interactive <tt>debian/rules</tt> script makes it
1904 impossible to auto-compile that package and also makes it
1905 hard for other people to reproduce the same binary
1906 package, all <em>required targets</em> MUST be
1907 non-interactive. At a minimum, required targets are the
1908 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1909 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1910 <em>binary-indep</em>, and <em>build</em>. It also follows
1911 that any target that these targets depend on must also be
1916 The required and optional targets are as follows:
1918 <tag><tt>build</tt></tag>
1921 This should perform all non-interactive configuration
1922 and compilation of the package. If a package has an
1923 interactive pre-build configuration routine, the
1924 Debianized source package must either be built after
1925 this has taken place (so that the binary package can
1926 be built without rerunning the configuration) or the
1927 configuration routine modified to become
1928 non-interactive. (The latter is preferable if there
1929 are architecture-specific features detected by the
1930 configuration routine.)
1934 For some packages, notably ones where the same
1935 source tree is compiled in different ways to produce
1936 two binary packages, the <prgn>build</prgn> target
1937 does not make much sense. For these packages it is
1938 good enough to provide two (or more) targets
1939 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1940 for each of the ways of building the package, and a
1941 <prgn>build</prgn> target that does nothing. The
1942 <prgn>binary</prgn> target will have to build the
1943 package in each of the possible ways and make the
1944 binary package out of each.
1948 The <prgn>build</prgn> target must not do anything
1949 that might require root privilege.
1953 The <prgn>build</prgn> target may need to run the
1954 <prgn>clean</prgn> target first - see below.
1958 When a package has a configuration and build routine
1959 which takes a long time, or when the makefiles are
1960 poorly designed, or when <prgn>build</prgn> needs to
1961 run <prgn>clean</prgn> first, it is a good idea to
1962 <tt>touch build</tt> when the build process is
1963 complete. This will ensure that if <tt>debian/rules
1964 build</tt> is run again it will not rebuild the whole
1968 Another common way to do this is for <prgn>build</prgn>
1969 to depend on <prgn>build-stamp</prgn> and to do
1970 nothing else, and for the <prgn>build-stamp</prgn>
1971 target to do the building and to <tt>touch
1972 build-stamp</tt> on completion. This is
1973 especially useful if the build routine creates a
1974 file or directory called <tt>build</tt>; in such a
1975 case, <prgn>build</prgn> will need to be listed as
1976 a phony target (i.e., as a dependency of the
1977 <tt>.PHONY</tt> target). See the documentation of
1978 <prgn>make</prgn> for more information on phony
1985 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1986 <tt>binary-indep</tt>
1990 The <prgn>binary</prgn> target must be all that is
1991 necessary for the user to build the binary package(s)
1992 produced from this source package. All of these
1993 targets are required to be non-interactive. It is
1994 split into two parts: <prgn>binary-arch</prgn> builds
1995 the binary packages which are specific to a particular
1996 architecture, and <prgn>binary-indep</prgn> builds
1997 those which are not.
2001 <prgn>binary</prgn> may be (and commonly is) a target
2002 with no commands which simply depends on
2003 <prgn>binary-arch</prgn> and
2004 <prgn>binary-indep</prgn>.
2008 Each <prgn>binary-*</prgn> target should depend on
2009 the <prgn>build</prgn> target, above, so that the
2010 package is built if it has not been already. It
2011 should then create the relevant binary package(s),
2012 using <prgn>dpkg-gencontrol</prgn> to make their
2013 control files and <prgn>dpkg-deb</prgn> to build
2014 them and place them in the parent of the top level
2019 Both the <prgn>binary-arch</prgn> and
2020 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2021 If one of them has nothing to do (which will always be
2022 the case if the source generates only a single binary
2023 package, whether architecture-dependent or not), it
2024 must still exist and must always succeed.
2028 The <prgn>binary</prgn> targets must be invoked as
2032 The <prgn>fakeroot</prgn> package often allows one
2033 to build a package correctly even without being
2040 <tag><tt>clean</tt></tag>
2044 This must undo any effects that the <prgn>build</prgn>
2045 and <prgn>binary</prgn> targets may have had, except
2046 that it should leave alone any output files created in
2047 the parent directory by a run of a <prgn>binary</prgn>
2048 target. This target must be non-interactive.
2052 If a <prgn>build</prgn> file is touched at the end of
2053 the <prgn>build</prgn> target, as suggested above, it
2054 should be removed as the first action that
2055 <prgn>clean</prgn> performs, so that running
2056 <prgn>build</prgn> again after an interrupted
2057 <prgn>clean</prgn> doesn't think that everything is
2062 The <prgn>clean</prgn> target may need to be
2063 invoked as root if <prgn>binary</prgn> has been
2064 invoked since the last <prgn>clean</prgn>, or if
2065 <prgn>build</prgn> has been invoked as root (since
2066 <prgn>build</prgn> may create directories, for
2071 <tag><tt>get-orig-source</tt> (optional)</tag>
2075 This target fetches the most recent version of the
2076 original source package from a canonical archive site
2077 (via FTP or WWW, for example), does any necessary
2078 rearrangement to turn it into the original source
2079 tar file format described below, and leaves it in the
2084 This target may be invoked in any directory, and
2085 should take care to clean up any temporary files it
2090 This target is optional, but providing it if
2091 possible is a good idea.
2097 The <prgn>build</prgn>, <prgn>binary</prgn> and
2098 <prgn>clean</prgn> targets must be invoked with the current
2099 directory being the package's top-level directory.
2104 Additional targets may exist in <tt>debian/rules</tt>,
2105 either as published or undocumented interfaces or for the
2106 package's internal use.
2110 The architectures we build on and build for are determined
2111 by <prgn>make</prgn> variables using the utility
2112 <prgn>dpkg-architecture</prgn>. You can determine the
2113 Debian architecture and the GNU style architecture
2114 specification string for the build machine (the machine type
2115 we are building on) as well as for the host machine (the
2116 machine type we are building for). Here is a list of
2117 supported <prgn>make</prgn> variables:
2118 <list compact="compact">
2120 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2123 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2124 specification string)</p>
2127 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2128 <tt>DEB_*_GNU_TYPE</tt>)</p>
2131 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2132 <tt>DEB_*_GNU_TYPE</tt>)</p>
2134 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2135 the build machine or <tt>HOST</tt> for specification of the
2140 Backward compatibility can be provided in the rules file
2141 by setting the needed variables to suitable default
2142 values; please refer to the documentation of
2143 <prgn>dpkg-architecture</prgn> for details.
2147 It is important to understand that the <tt>DEB_*_ARCH</tt>
2148 string only determines which Debian architecture we are
2149 building on or for. It should not be used to get the CPU
2150 or system information; the GNU style variables should be
2155 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2159 This file records the changes to the Debian-specific parts of the
2163 Though there is nothing stopping an author who is also
2164 the Debian maintainer from using it for all their
2165 changes, it will have to be renamed if the Debian and
2166 upstream maintainers become different people. In such a
2167 case, however, it might be better to maintain the
2168 package as a non-native package.
2174 It has a special format which allows the package building
2175 tools to discover which version of the package is being
2176 built and find out other release-specific information.
2180 That format is a series of entries like this:
2182 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2184 * <var>change details</var>
2185 <var>more change details</var>
2186 * <var>even more change details</var>
2188 -- <var>maintainer name and email address</var> <var>date</var>
2193 <var>package</var> and <var>version</var> are the source
2194 package name and version number.
2198 <var>distribution(s)</var> lists the distributions where
2199 this version should be installed when it is uploaded - it
2200 is copied to the <tt>Distribution</tt> field in the
2201 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2205 <var>urgency</var> is the value for the <tt>Urgency</tt>
2206 field in the <tt>.changes</tt> file for the upload. It is
2207 not possible to specify an urgency containing commas; commas
2208 are used to separate
2209 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2210 <prgn>dpkg</prgn> changelog format (though there is
2211 currently only one useful <var>keyword</var>,
2215 Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
2216 <tt>high</tt> and <tt>critical</tt>. They have an
2217 effect on how quickly a package will be considered for
2218 inclusion into the <tt>testing</tt> distribution, and
2219 give an indication of the importance of any fixes
2220 included in this upload.
2226 The change details may in fact be any series of lines
2227 starting with at least two spaces, but conventionally each
2228 change starts with an asterisk and a separating space and
2229 continuation lines are indented so as to bring them in
2230 line with the start of the text above. Blank lines may be
2231 used here to separate groups of changes, if desired.
2235 If this upload resolves bugs recorded in the Bug Tracking
2236 System (BTS), they may be automatically closed on the
2237 inclusion of this package into the Debian archive by
2238 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2239 in the change details.
2242 To be precise, the string should match the following
2243 Perl regular expression:
2244 <tt>/closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i</tt>
2245 Then all of the bug numbers listed will be closed by the
2246 archive maintenance script (<prgn>katie</prgn>), or in
2247 the case of an NMU, marked as fixed.
2253 The maintainer name and email address used in the changelog
2254 should be the details of the person uploading <em>this</em>
2255 version. They are <em>not</em> necessarily those of the
2256 usual package maintainer. The information here will be
2257 copied to the <tt>Changed-By</tt> field in the
2258 <tt>.changes</tt> file, and then later used to send an
2259 acknowledgement when the upload has been installed.
2263 The <var>date</var> should be in RFC822 format
2266 This is generated by the <prgn>822-date</prgn>
2269 </footnote>; it should include the time zone specified
2270 numerically, with the time zone name or abbreviation
2271 optionally present as a comment in parentheses.
2275 The first `title' line with the package name should start
2276 at the left hand margin; the `trailer' line with the
2277 maintainer and date details should be preceded by exactly
2278 one space. The maintainer details and the date must be
2279 separated by exactly two spaces.
2282 <sect1><heading>Defining alternative changelog formats</heading>
2285 It is possible to use a different format to the standard
2286 one, by providing a parser for the format you wish to
2290 A changelog parser must not interact with the user at
2296 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2297 and variable substitutions </heading>
2300 When <prgn>dpkg-gencontrol</prgn>,
2301 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2302 generate control files they perform variable substitutions
2303 on their output just before writing it. Variable
2304 substitutions have the form
2305 <tt>${<var>variable-name</var>}</tt>. The optional file
2306 <tt>debian/substvars</tt> contains variable substitutions to
2307 be used; variables can also be set directly from
2308 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2309 source packaging commands, and certain predefined variables
2314 The <tt>debian/substvars</tt> file is usually generated and
2315 modified dynamically by <tt>debian/rules</tt> targets; in
2316 this case it must be removed by the <prgn>clean</prgn>
2321 See <manref name="dpkg-source" section="1"> for full
2322 details about source variable substitutions, including the
2323 format of <tt>debian/substvars</tt>.</p>
2326 <sect id="debianfiles"><heading><tt>debian/files</tt>
2330 This file is not a permanent part of the source tree; it
2331 is used while building packages to record which files are
2332 being generated. <prgn>dpkg-genchanges</prgn> uses it
2333 when it generates a <tt>.changes</tt> file.
2337 It should not exist in a shipped source package, and so it
2338 (and any backup files or temporary files such as
2342 <tt>files.new</tt> is used as a temporary file by
2343 <prgn>dpkg-gencontrol</prgn> and
2344 <prgn>dpkg-distaddfile</prgn> - they write a new
2345 version of <tt>files</tt> here before renaming it,
2346 to avoid leaving a corrupted copy if an error
2349 </footnote>) should be removed by the
2350 <prgn>clean</prgn> target. It may also be wise to
2351 ensure a fresh start by emptying or removing it at the
2352 start of the <prgn>binary</prgn> target.
2356 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2357 package, it adds an entry to <tt>debian/files</tt> for the
2358 <tt>.deb</tt> file that will be created when <prgn>dpkg-deb
2359 --build</prgn> is run for that binary package. So for most
2360 packages all that needs to be done with this file is to
2361 delete it in the <prgn>clean</prgn> target.
2365 If a package upload includes files besides the source
2366 package and any binary packages whose control files were
2367 made with <prgn>dpkg-gencontrol</prgn> then they should be
2368 placed in the parent of the package's top-level directory
2369 and <prgn>dpkg-distaddfile</prgn> should be called to add
2370 the file to the list in <tt>debian/files</tt>.</p>
2373 <sect id="restrictions"><heading>Restrictions on objects in source packages
2377 The source package may not contain any hard links
2380 This is not currently detected when building source
2381 packages, but only when extracting
2385 Hard links may be permitted at some point in the
2386 future, but would require a fair amount of
2389 </footnote>, device special files, sockets or setuid or
2393 Setgid directories are allowed.
2398 <sect id="descriptions"><heading>Descriptions of packages - the
2399 <tt>Description</tt> field </heading>
2402 The description is intended to describe the program to a user
2403 who has never met it before so that they know whether they
2404 want to install it. It should also give information about the
2405 significant dependencies and conflicts between this package
2406 and others, so that the user knows why these dependencies and
2407 conflicts have been declared.
2410 <sect1><heading>Notes about writing descriptions
2414 The single line synopsis should be kept brief - certainly
2415 under 80 characters.
2419 Do not include the package name in the synopsis line. The
2420 display software knows how to display this already, and you
2421 do not need to state it. Remember that in many situations
2422 the user may only see the synopsis line - make it as
2423 informative as you can.
2427 Do not try to continue the single line synopsis into the
2428 extended description. This will not work correctly when
2429 the full description is displayed, and makes no sense
2430 where only the summary (the single line synopsis) is
2435 The extended description should describe what the package
2436 does and how it relates to the rest of the system (in terms
2437 of, for example, which subsystem it is which part of).
2441 The description field needs to make sense to anyone, even
2442 people who have no idea about any of the things the
2446 The blurb that comes with a program in its
2447 announcements and/or <prgn>README</prgn> files is
2448 rarely suitable for use in a description. It is
2449 usually aimed at people who are already in the
2450 community where the package is used.
2456 Put important information first, both in the synopsis and
2457 extended description. Sometimes only the first part of the
2458 synopsis or of the description will be displayed. You can
2459 assume that there will usually be a way to see the whole
2460 extended description.
2464 You may include information about dependencies and so forth
2465 in the extended description, if you wish.
2469 Do not use tab characters. Their effect is not predictable.
2477 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2478 and installation procedure
2481 <sect><heading>Introduction to package maintainer scripts
2485 It is possible to supply scripts as part of a package which
2486 the package management system will run for you when your
2487 package is installed, upgraded or removed.
2491 These scripts are the files <tt>preinst</tt>,
2492 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2493 control area of the package. They must be proper executable
2494 files; if they are scripts (which is recommended), they must
2495 start with the usual <tt>#!</tt> convention. They should be
2496 readable and executable by anyone, and not world-writable.
2500 The package management system looks at the exit status from
2501 these scripts. It is important that they exit with a
2502 non-zero status if there is an error, so that the package
2503 management system can stop its processing. For shell
2504 scripts this means that you <em>almost always</em> need to
2505 use <tt>set -e</tt> (this is usually true when writing shell
2506 scripts, in fact). It is also important, of course, that
2507 they don't exit with a non-zero status if everything went
2512 When a package is upgraded a combination of the scripts from
2513 the old and new packages is called during the upgrade
2514 procedure. If your scripts are going to be at all
2515 complicated you need to be aware of this, and may need to
2516 check the arguments to your scripts.
2520 Broadly speaking the <prgn>preinst</prgn> is called before
2521 (a particular version of) a package is installed, and the
2522 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2523 before (a version of) a package is removed and the
2524 <prgn>postrm</prgn> afterwards.
2528 Programs called from maintainer scripts should not normally
2529 have a path prepended to them. Before installation is
2530 started, the package management system checks to see if the
2531 programs <prgn>ldconfig</prgn>,
2532 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2533 and <prgn>update-rc.d</prgn> can be found via the
2534 <tt>PATH</tt> environment variable. Those programs, and any
2535 other program that one would expect to be on the
2536 <tt>PATH</tt>, should thus be invoked without an absolute
2537 pathname. Maintainer scripts should also not reset the
2538 <tt>PATH</tt>, though they might choose to modify it by
2539 prepending or appending package-specific directories. These
2540 considerations really apply to all shell scripts.</p>
2544 <heading>Maintainer scripts Idempotency</heading>
2547 It is necessary for the error recovery procedures that the
2548 scripts be idempotent. This means that if it is run
2549 successfully, and then it is called again, it doesn't bomb
2550 out or cause any harm, but just ensures that everything is
2551 the way it ought to be. If the first call failed, or
2552 aborted half way through for some reason, the second call
2553 should merely do the things that were left undone the first
2554 time, if any, and exit with a success status if everything
2558 This is so that if an error occurs, the user interrupts
2559 <prgn>dpkg</prgn> or some other unforeseen circumstance
2560 happens you don't leave the user with a badly-broken
2561 package when <prgn>dpkg</prgn> attempts to repeat the
2569 <heading>Controlling terminal for maintainer scripts</heading>
2572 The maintainer scripts are guaranteed to run with a
2573 controlling terminal and can interact with the user.
2574 If they need to prompt for passwords, do full-screen
2575 interaction or something similar you should do these
2576 things to and from <tt>/dev/tty</tt>, since
2577 <prgn>dpkg</prgn> will at some point redirect scripts'
2578 standard input and output so that it can log the
2579 installation process. Likewise, because these scripts
2580 may be executed with standard output redirected into a
2581 pipe for logging purposes, Perl scripts should set
2582 unbuffered output by setting <tt>$|=1</tt> so that the
2583 output is printed immediately rather than being
2588 Each script should return a zero exit status for
2589 success, or a nonzero one for failure.
2593 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2598 <list compact="compact">
2600 <p><var>new-preinst</var> <tt>install</tt></p>
2603 <p><var>new-preinst</var> <tt>install</tt>
2604 <var>old-version</var></p>
2607 <p><var>new-preinst</var> <tt>upgrade</tt>
2608 <var>old-version</var></p>
2611 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2612 <var>new-version</var>
2618 <list compact="compact">
2620 <p><var>postinst</var> <tt>configure</tt>
2621 <var>most-recently-configured-version</var></p>
2624 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2625 <var>new-version</var></p>
2628 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2629 <tt>in-favour</tt> <var>package</var>
2630 <var>new-version</var></p>
2634 <var>deconfigured's-postinst</var>
2635 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2636 <var>failed-install-package</var> <var>version</var>
2637 <tt>removing</tt> <var>conflicting-package</var>
2644 <list compact="compact">
2646 <p><var>prerm</var> <tt>remove</tt></p>
2649 <p><var>old-prerm</var> <tt>upgrade</tt>
2650 <var>new-version</var></p>
2653 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2654 <var>old-version</var></p>
2657 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2658 <tt>in-favour</tt> <var>package</var>
2659 <var>new-version</var></p>
2663 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2664 <tt>in-favour</tt> <var>package-being-installed</var>
2665 <var>version</var> <tt>removing</tt>
2666 <var>conflicting-package</var>
2673 <list compact="compact">
2675 <p><var>postrm</var> <tt>remove</tt></p>
2678 <p><var>postrm</var> <tt>purge</tt></p>
2682 <var>old-postrm</var> <tt>upgrade</tt>
2683 <var>new-version</var></p>
2686 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2687 <var>old-version</var></p>
2690 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2693 <p><var>new-postrm</var> <tt>abort-install</tt>
2694 <var>old-version</var></p>
2697 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2698 <var>old-version</var></p>
2702 <var>disappearer's-postrm</var> <tt>disappear</tt>
2703 <var>overwriter</var>
2704 <var>overwriter-version</var></p></item>
2709 <sect id="unpackphase"><heading>Details of unpack phase of
2710 installation or upgrade
2714 The procedure on installation/upgrade/overwrite/disappear
2715 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2716 stage of <tt>dpkg --install</tt>) is as follows. In each
2717 case, if a major error occurs (unless listed below) the
2718 actions are, in general, run backwards - this means that the
2719 maintainer scripts are run with different arguments in
2720 reverse order. These are the `error unwind' calls listed
2728 <p>If a version of the package is already
2731 <var>old-prerm</var> upgrade <var>new-version</var>
2736 If the script runs but exits with a non-zero
2737 exit status, <prgn>dpkg</prgn> will attempt:
2739 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2741 Error unwind, for both the above cases:
2743 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2751 <p>If a `conflicting' package is being removed at the same time:
2755 If any packages depended on that conflicting
2756 package and <tt>--auto-deconfigure</tt> is
2757 specified, call, for each such package:
2759 <var>deconfigured's-prerm</var> deconfigure \
2760 in-favour <var>package-being-installed</var> <var>version</var> \
2761 removing <var>conflicting-package</var> <var>version</var>
2765 <var>deconfigured's-postinst</var> abort-deconfigure \
2766 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2767 removing <var>conflicting-package</var> <var>version</var>
2769 The deconfigured packages are marked as
2770 requiring configuration, so that if
2771 <tt>--install</tt> is used they will be
2772 configured again if possible.</p>
2775 <p>To prepare for removal of the conflicting package, call:
2777 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2781 <var>conflictor's-postinst</var> abort-remove \
2782 in-favour <var>package</var> <var>new-version</var>
2793 <p>If the package is being upgraded, call:
2795 <var>new-preinst</var> upgrade <var>old-version</var>
2800 Otherwise, if the package had some configuration
2801 files from a previous version installed (i.e., it
2802 is in the `configuration files only' state):
2804 <var>new-preinst</var> install <var>old-version</var>
2808 <p>Otherwise (i.e., the package was completely purged):
2810 <var>new-preinst</var> install
2812 Error unwind actions, respectively:
2814 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2815 <var>new-postrm</var> abort-install <var>old-version</var>
2816 <var>new-postrm</var> abort-install
2826 The new package's files are unpacked, overwriting any
2827 that may be on the system already, for example any
2828 from the old version of the same package or from
2829 another package. Backups of the old files are kept
2830 temporarily, and if anything goes wrong the package
2831 management system will attempt to put them back as
2832 part of the error unwind.
2836 It is an error for a package to contains files which
2837 are on the system in another package, unless
2838 <tt>Replaces</tt> is used (see <ref id="replaces">).
2840 The following paragraph is not currently the case:
2841 Currently the <tt>- - force-overwrite</tt> flag is
2842 enabled, downgrading it to a warning, but this may not
2848 It is a more serious error for a package to contain a
2849 plain file or other kind of non-directory where another
2850 package has a directory (again, unless
2851 <tt>Replaces</tt> is used). This error can be
2852 overridden if desired using
2853 <tt>--force-overwrite-dir</tt>, but this is not
2858 Packages which overwrite each other's files produce
2859 behavior which, though deterministic, is hard for the
2860 system administrator to understand. It can easily
2861 lead to `missing' programs if, for example, a package
2862 is installed which overwrites a file from another
2863 package, and is then removed again.
2866 Part of the problem is due to what is arguably a
2867 bug in <prgn>dpkg</prgn>.
2873 A directory will never be replaced by a symbolic link
2874 to a directory or vice versa; instead, the existing
2875 state (symlink or not) will be left alone and
2876 <prgn>dpkg</prgn> will follow the symlink if there is
2884 <p>If the package is being upgraded, call
2886 <var>old-postrm</var> upgrade <var>new-version</var>
2890 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2892 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2894 Error unwind, for both cases:
2896 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2902 This is the point of no return - if
2903 <prgn>dpkg</prgn> gets this far, it won't back off
2904 past this point if an error occurs. This will
2905 leave the package in a fairly bad state, which
2906 will require a successful re-installation to clear
2907 up, but it's when <prgn>dpkg</prgn> starts doing
2908 things that are irreversible.
2913 Any files which were in the old version of the package
2914 but not in the new are removed.</p>
2917 <p>The new file list replaces the old.</p>
2920 <p>The new maintainer scripts replace the old.</p>
2924 <p>Any packages all of whose files have been overwritten during the
2925 installation, and which aren't required for
2926 dependencies, are considered to have been removed.
2927 For each such package
2930 <p><prgn>dpkg</prgn> calls:
2932 <var>disappearer's-postrm</var> disappear \
2933 <var>overwriter</var> <var>overwriter-version</var>
2938 <p>The package's maintainer scripts are removed.
2943 It is noted in the status database as being in a
2944 sane state, namely not installed (any conffiles
2945 it may have are ignored, rather than being
2946 removed by <prgn>dpkg</prgn>). Note that
2947 disappearing packages do not have their prerm
2948 called, because <prgn>dpkg</prgn> doesn't know
2949 in advance that the package is going to
2958 Any files in the package we're unpacking that are also
2959 listed in the file lists of other packages are removed
2960 from those lists. (This will lobotomize the file list
2961 of the `conflicting' package if there is one.)
2966 The backup files made during installation, above, are
2973 The new package's status is now sane, and recorded as
2978 Here is another point of no return - if the
2979 conflicting package's removal fails we do not unwind
2980 the rest of the installation; the conflicting package
2981 is left in a half-removed limbo.
2987 If there was a conflicting package we go and do the
2988 removal actions (described below), starting with the
2989 removal of the conflicting package's files (any that
2990 are also in the package being installed have already
2991 been removed from the conflicting package's file list,
2992 and so do not get removed now).
2999 <sect><heading>Details of configuration</heading>
3002 When we configure a package (this happens with <tt>dpkg
3003 --install</tt>, or with <tt>--configure</tt>), we first
3004 update any <tt>conffile</tt>s and then call:
3006 <var>postinst</var> configure <var>most-recently-configured-version</var>
3011 No attempt is made to unwind after errors during
3016 If there is no most recently configured version
3017 <prgn>dpkg</prgn> will pass a null argument; older versions
3018 of dpkg may pass <tt><unknown></tt> (including the
3019 angle brackets) in this case. Even older ones do not pass a
3020 second argument at all, under any circumstances.
3024 <sect><heading>Details of removal and/or configuration purging
3032 <var>prerm</var> remove
3038 The package's files are removed (except <tt>conffile</tt>s).
3043 <var>postrm</var> remove
3048 All the maintainer scripts except the <tt>postrm</tt>
3053 If we aren't purging the package we stop here. Note
3054 that packages which have no <tt>postrm</tt> and no
3055 <tt>conffile</tt>s are automatically purged when
3056 removed, as there is no difference except for the
3057 <prgn>dpkg</prgn> status.</p>
3061 The conffiles and any backup files (<tt>~</tt>-files,
3062 <tt>#*#</tt> files, <tt>%</tt>-files,
3063 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3067 <var>postrm</var> purge
3071 <p>The package's file list is removed.</p>
3074 No attempt is made to unwind after errors during
3081 <chapt id="relationships"><heading>Declaring relationships between
3085 Packages can declare in their control file that they have
3086 certain relationships to other packages - for example, that
3087 they may not be installed at the same time as certain other
3088 packages, and/or that they depend on the presence of others,
3089 or that they should overwrite files in certain other packages
3094 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3095 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3096 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3097 control file fields.
3101 Source packages may declare relationships to binary packages,
3102 saying that they require certain binary packages to be
3103 installed or absent at the time of building the package.
3107 This is done using the <tt>Build-Depends</tt>,
3108 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3109 <tt>Build-Conflicts-Indep</tt> control file fields.
3112 <sect id="depsyntax"><heading>Syntax of relationship fields
3116 These fields all have a uniform syntax. They are a list of
3117 package names separated by commas.
3121 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3122 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3123 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3124 control file fields of the package, which declare
3125 dependencies on other packages, the package names listed may
3126 also include lists of alternative package names, separated
3127 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3128 if any one of the alternative packages is installed, that
3129 part of the dependency is considered to be satisfied.
3133 All of the fields except for <tt>Provides</tt> may restrict
3134 their applicability to particular versions of each named
3135 package. This is done in parentheses after each individual
3136 package name; the parentheses should contain a relation from
3137 the list below followed by a version number, in the format
3138 described in <ref id="versions">.
3142 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3143 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3144 strictly earlier, earlier or equal, exactly equal, later or
3145 equal and strictly later, respectively. The deprecated
3146 forms <tt><</tt> and <tt>></tt> were used to mean
3147 earlier/later or equal, rather than strictly earlier/later,
3148 so they should not appear in new packages (though
3149 <prgn>dpkg</prgn> still supports them).
3153 Whitespace may appear at any point in the version
3154 specification subject to the rules in <ref
3155 id="controlsyntax">, and must appear where it's necessary to
3156 disambiguate; it is not otherwise significant. For
3157 consistency and in case of future changes to
3158 <prgn>dpkg</prgn> it is recommended that a single space be
3159 used after a version relationship and before a version
3160 number; it is also conventional to put a single space after
3161 each comma, on either side of each vertical bar, and before
3162 each open parenthesis.
3166 For example, a list of dependencies might appear as:
3170 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3175 All fields that specify build-time relationships
3176 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3177 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3178 may be restricted to a certain set of architectures. This
3179 is indicated in brackets after each individual package name and
3180 the optional version specification. The brackets enclose a
3181 list of Debian architecture names separated by whitespace.
3182 Exclamation marks may be prepended to each of the names.
3183 (It is not permitted for some names to be prepended with
3184 exclamation marks and others not.) If the current Debian
3185 host architecture is not in this list and there are no
3186 exclamation marks in the list, or it is in the list with a
3187 prepended exclamation mark, the package name and the
3188 associated version specification are ignored completely for
3189 the purposes of defining the relationships.
3196 Build-Depends-Indep: texinfo
3197 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3198 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3204 <heading>Binary Dependencies - <tt>Depends</tt>,
3205 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3206 <tt>Pre-Depends</tt>
3210 These five fields are used to declare a dependency
3211 relationship by one package on another. They appear in the
3212 depending package's control file.
3216 A <tt>Depends</tt> field takes effect <em>only</em> when a
3217 package is to be configured. It does not prevent a package
3218 being on the system in an unconfigured state while its
3219 dependencies are unsatisfied, and it is possible to replace
3220 a package whose dependencies are satisfied and which is
3221 properly installed with a different version whose
3222 dependencies are not and cannot be satisfied; when this is
3223 done the depending package will be left unconfigured (since
3224 attempts to configure it will give errors) and will not
3225 function properly. If it is necessary, a
3226 <tt>Pre-Depends</tt> field can be used, which has a partial
3227 effect even when a package is being unpacked, as explained
3228 in detail below. (The other three dependency fields,
3229 <tt>Recommends</tt>, <tt>Suggests</tt> and
3230 <tt>Enhances</tt>, are only used by the various front-ends
3231 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3235 For this reason packages in an installation run are usually
3236 all unpacked first and all configured later; this gives
3237 later versions of packages with dependencies on later
3238 versions of other packages the opportunity to have their
3239 dependencies satisfied.
3243 The <tt>Depends</tt> field thus allows package maintainers
3244 to impose an order in which packages should be configured.
3248 The meaning of the five dependency fields is as follows:
3250 <tag><tt>Depends</tt></tag>
3254 This declares an absolute dependency. A package will
3255 not be configured unless all of the packages listed in
3256 its <tt>Depends</tt> field have been correctly
3261 The <tt>Depends</tt> field should be used if the
3262 depended-on package is required for the depending
3263 package to provide a significant amount of
3267 The <tt>Depends</tt> field should also be used if the
3268 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3269 <prgn>postrm</prgn> scripts require the package to be
3270 present in order to run. Note, however, that the
3271 <prgn>postrm</prgn> cannot rely on any non-essential
3272 packages to be present during the <tt>purge</tt>
3276 <tag><tt>Recommends</tt></tag>
3278 <p>This declares a strong, but not absolute, dependency.
3282 The <tt>Recommends</tt> field should list packages
3283 that would be found together with this one in all but
3284 unusual installations.</p>
3287 <tag><tt>Suggests</tt></tag>
3291 This is used to declare that one package may be more
3292 useful with one or more others. Using this field
3293 tells the packaging system and the user that the
3294 listed packages are related to this one and can
3295 perhaps enhance its usefulness, but that installing
3296 this one without them is perfectly reasonable.
3300 <tag><tt>Enhances</tt></tag>
3303 This field is similar to Suggests but works in the
3304 opposite direction. It is used to declare that a
3305 package can enhance the functionality of another
3310 <tag><tt>Pre-Depends</tt></tag>
3314 This field is like <tt>Depends</tt>, except that it
3315 also forces <prgn>dpkg</prgn> to complete installation
3316 of the packages named before even starting the
3317 installation of the package which declares the
3318 pre-dependency, as follows:
3322 When a package declaring a pre-dependency is about to
3323 be <em>unpacked</em> the pre-dependency can be
3324 satisfied if the depended-on package is either fully
3325 configured, <em>or even if</em> the depended-on
3326 package(s) are only unpacked or half-configured,
3327 provided that they have been configured correctly at
3328 some point in the past (and not removed or partially
3329 removed since). In this case, both the
3330 previously-configured and currently unpacked or
3331 half-configured versions must satisfy any version
3332 clause in the <tt>Pre-Depends</tt> field.
3336 When the package declaring a pre-dependency is about
3337 to be <em>configured</em>, the pre-dependency will be
3338 treated as a normal <tt>Depends</tt>, that is, it will
3339 be considered satisfied only if the depended-on
3340 package has been correctly configured.
3344 <tt>Pre-Depends</tt> should be used sparingly,
3345 preferably only by packages whose premature upgrade or
3346 installation would hamper the ability of the system to
3347 continue with any upgrade that might be in progress.
3351 <tt>Pre-Depends</tt> are also required if the
3352 <prgn>preinst</prgn> script depends on the named
3353 package. It is best to avoid this situation if
3359 When selecting which level of dependency to use you should
3360 consider how important the depended-on package is to the
3361 functionality of the one declaring the dependency. Some
3362 packages are composed of components of varying degrees of
3363 importance. Such a package should list using
3364 <tt>Depends</tt> the package(s) which are required by the
3365 more important components. The other components'
3366 requirements may be mentioned as Suggestions or
3367 Recommendations, as appropriate to the components' relative
3372 <sect id="conflicts"><heading>Conflicting binary packages -
3373 <tt>Conflicts</tt></heading>
3376 When one binary package declares a conflict with another
3377 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3378 refuse to allow them to be installed on the system at the
3383 If one package is to be installed, the other must be removed
3384 first - if the package being installed is marked as
3385 replacing (see <ref id="replaces">) the one on the system,
3386 or the one on the system is marked as deselected, or both
3387 packages are marked <tt>Essential</tt>, then
3388 <prgn>dpkg</prgn> will automatically remove the package
3389 which is causing the conflict, otherwise it will halt the
3390 installation of the new package with an error. This
3391 mechanism is specifically designed to produce an error when
3392 the installed package is <tt>Essential</tt>, but the new
3397 A package will not cause a conflict merely because its
3398 configuration files are still installed; it must be at least
3403 A special exception is made for packages which declare a
3404 conflict with their own package name, or with a virtual
3405 package which they provide (see below): this does not
3406 prevent their installation, and allows a package to conflict
3407 with others providing a replacement for it. You use this
3408 feature when you want the package in question to be the only
3409 package providing some feature.
3413 A <tt>Conflicts</tt> entry should almost never have an
3414 `earlier than' version clause. This would prevent
3415 <prgn>dpkg</prgn> from upgrading or installing the package
3416 which declared such a conflict until the upgrade or removal
3417 of the conflicted-with package had been completed.
3421 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3425 As well as the names of actual (`concrete') packages, the
3426 package relationship fields <tt>Depends</tt>,
3427 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3428 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3429 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3430 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3431 may mention `virtual packages'.
3435 A <em>virtual package</em> is one which appears in the
3436 <tt>Provides</tt> control file field of another package.
3437 The effect is as if the package(s) which provide a
3438 particular virtual package name had been listed by name
3439 everywhere the virtual package name appears.
3443 If there are both a real and a virtual package of the same
3444 name then the dependency may be satisfied (or the conflict
3445 caused) by either the real package or any of the virtual
3446 packages which provide it. This is so that, for example,
3452 and someone else releases an enhanced version of the
3453 <tt>bar</tt> package (for example, a non-US variant), they
3459 and the <tt>bar-plus</tt> package will now also satisfy the
3460 dependency for the <tt>foo</tt> package.
3464 If a dependency or a conflict has a version number attached
3465 then only real packages will be considered to see whether
3466 the relationship is satisfied (or the prohibition violated,
3467 for a conflict) - it is assumed that a real package which
3468 provides the virtual package is not of the `right' version.
3469 So, a <tt>Provides</tt> field may not contain version
3470 numbers, and the version number of the concrete package
3471 which provides a particular virtual package will not be
3472 looked at when considering a dependency on or conflict with
3473 the virtual package name.
3477 It is likely that the ability will be added in a future
3478 release of <prgn>dpkg</prgn> to specify a version number for
3479 each virtual package it provides. This feature is not yet
3480 present, however, and is expected to be used only
3485 If you want to specify which of a set of real packages
3486 should be the default to satisfy a particular dependency on
3487 a virtual package, you should list the real package as an
3488 alternative before the virtual one.
3493 <sect id="replaces"><heading>Overwriting files and replacing
3494 packages - <tt>Replaces</tt></heading>
3497 The <tt>Replaces</tt> control file field has two distinct
3498 purposes, which come into play in different situations.
3501 <sect1><heading>Overwriting files in other packages</heading>
3504 Firstly, as mentioned before, it is usually an error for a
3505 package to contain files which are on the system in
3510 However, if the overwriting package declares that it
3511 <tt>Replaces</tt> the one containing the file being
3512 overwritten, then <prgn>dpkg</prgn> will replace the file
3513 from the old package with that from the new. The file
3514 will no longer be listed as `owned' by the old package.
3518 If a package is completely replaced in this way, so that
3519 <prgn>dpkg</prgn> does not know of any files it still
3520 contains, it is considered to have `disappeared'. It will
3521 be marked as not wanted on the system (selected for
3522 removal) and not installed. Any <tt>conffile</tt>s
3523 details noted for the package will be ignored, as they
3524 will have been taken over by the overwriting package. The
3525 package's <prgn>postrm</prgn> script will be run with a
3526 special argument to allow the package to do any final
3527 cleanup required. See <ref id="mscriptsinstact">.
3531 If an installed package, <tt>foo</tt> say, declares that
3532 it replaces another, <tt>bar</tt>, and an attempt is made
3533 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3534 files in the <tt>bar</tt> package which would overwrite
3535 those already present in <tt>foo</tt>. This is so that
3536 you can install an older version of a package without
3541 For this usage of <tt>Replaces</tt>, virtual packages (see
3542 <ref id="virtual">) are not considered when looking at a
3543 <tt>Replaces</tt> field - the packages declared as being
3544 replaced must be mentioned by their real names.
3548 Furthermore, this usage of <tt>Replaces</tt> only takes
3549 effect when both packages are at least partially on the
3550 system at once, so that it can only happen if they do not
3551 conflict or if the conflict has been overridden.
3556 <sect1><heading>Replacing whole packages, forcing their
3560 Secondly, <tt>Replaces</tt> allows the packaging system to
3561 resolve which package should be removed when there is a
3562 conflict - see <ref id="conflicts">. This usage only
3563 takes effect when the two packages <em>do</em> conflict,
3564 so that the two usages of this field do not interfere with
3569 In this situation, the package declared as being replaced
3570 can be a virtual package, so for example, all mail
3571 transport agents (MTAs) would have the following fields in
3572 their control files:
3574 Provides: mail-transport-agent
3575 Conflicts: mail-transport-agent
3576 Replaces: mail-transport-agent
3578 ensuring that only one MTA can be installed at any one
3583 <sect><heading>Relationships between source and binary packages -
3584 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3585 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3589 A source package may declare a dependency or a conflict on a
3590 binary package, indicating which packages are required to be
3591 present on the system in order to build the binary packages
3592 from the source package. This is done with the control file
3593 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3594 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3595 The dependencies and conflicts they define must be satisfied
3596 (as defined earlier for binary packages) in order to invoke
3597 the targets in <tt>debian/rules</tt>, as follows:
3600 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3603 The <tt>Build-Depends</tt> and
3604 <tt>Build-Conflicts</tt> fields must be satisfied when
3605 any of the following targets is invoked:
3606 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3607 and <tt>binary-indep</tt>.
3610 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3613 The <tt>Build-Depends-Indep</tt> and
3614 <tt>Build-Conflicts-Indep</tt> fields must be
3615 satisfied when any of the following targets is
3616 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3627 <chapt id="conffiles"><heading>Configuration file handling
3631 This chapter has been superseded by <ref id="config files">.
3635 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3638 Packages containing shared libraries must be constructed with
3639 a little care to make sure that the shared library is always
3640 available. This is especially important for packages whose
3641 shared libraries are vitally important, such as the C library
3642 (currently <tt>libc6</tt>).
3646 Firstly, the package should install the shared libraries under
3647 their normal names. For example, the <tt>libgdbmg1</tt>
3648 package should install <tt>libgdbm.so.1.7.3</tt> as
3649 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3650 renamed or re-linked by any <prgn>prerm</prgn> or
3651 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3652 of renaming things safely without affecting running programs,
3653 and attempts to interfere with this are likely to lead to
3658 Secondly, the package should include the symbolic link that
3659 <prgn>ldconfig</prgn> would create for the shared libraries.
3660 For example, the <prgn>libgdbmg1</prgn> package should include
3661 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3662 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3663 linker (for example <prgn>ld.so</prgn> or
3664 <prgn>ld-linux.so.*</prgn>) can find the library between the
3665 time that <prgn>dpkg</prgn> installs it and the time that
3666 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3670 The package management system requires the library to be
3671 placed before the symbolic link pointing to it in the
3672 <tt>.deb</tt> file. This is so that when
3673 <prgn>dpkg</prgn> comes to install the symlink
3674 (overwriting the previous symlink pointing at an older
3675 version of the library), the new shared library is already
3676 in place. In the past, this was achieved by creating the
3677 library in the temporary packaging directory before
3678 creating the symlink. Unfortunately, this was not always
3679 effective, since the building of the tar file in the
3680 <tt>.deb</tt> depended on the behavior of the underlying
3681 file system. Some file systems (such as reiserfs) reorder
3682 the files so that the order of creation is forgotten.
3683 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3684 will reorder the files itself as necessary when building a
3685 package. Thus it is no longer important to concern
3686 oneself with the order of file creation.
3692 Thirdly, the associated development package should contain a
3693 symlink for the shared library without a version number. For
3694 example, the <tt>libgdbmg1-dev</tt> package should include a
3695 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3696 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3697 linker (<prgn>ld</prgn>) when compiling packages, as it will
3698 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3702 Any package installing shared libraries in a directory that is
3703 listed in <tt>/etc/ld.so.conf</tt> or in one of the default
3704 library directories of the dynamic linker (currently, these
3705 are <tt>/usr/lib</tt> and <tt>/lib</tt>) must call
3706 <prgn>ldconfig</prgn> in its <prgn>postinst</prgn> script if
3707 and only if the first argument is `configure'. However, it is
3708 important not to call <prgn>ldconfig</prgn> in the postrm or
3709 preinst scripts in the case where the package is being
3710 upgraded (see <ref id="unpackphase">), as
3711 <prgn>ldconfig</prgn> will see the temporary names that
3712 <prgn>dpkg</prgn> uses for the files while it is installing
3713 them and will make the shared library links point to them,
3714 just before <prgn>dpkg</prgn> continues the installation and
3718 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3722 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3723 required when your package provides shared libraries.
3727 Each line is of the form:
3729 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3734 <var>library-name</var> is the name of the shared library,
3735 for example <tt>libc5</tt>.
3739 <var>version-or-soname</var> is the soname of the library -
3740 i.e., the thing that must exactly match for the library to be
3741 recognized by <prgn>ld.so</prgn>. Usually this is the major
3742 version number of the library.
3746 <var>dependencies</var> has the same syntax as a dependency
3747 field in a binary package control file. It should give
3748 details of which package(s) are required to satisfy a binary
3749 built against the version of the library contained in the
3750 package. See <ref id="depsyntax">.
3754 For example, if the package <tt>foo</tt> contains
3755 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3756 <tt>libfoo.so.1</tt>, and the first version of the package
3757 which contained a minor number of at least <tt>2.3</tt> was
3758 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3761 libfoo 1 foo (>= 1.2.3-1)
3766 The version-specific dependency is to avoid warnings from
3767 <prgn>ld.so</prgn> about using older shared libraries with
3771 <sect><heading>Further Technical information on
3772 <tt>shlibs</tt></heading>
3774 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3778 The <tt>debian/shlibs</tt> file provides a way of checking
3779 for shared library dependencies on packaged binaries.
3780 They are intended to be used by package maintainers to
3781 make their lives easier.
3785 Other <tt>shlibs</tt> files that exist on a Debian system are
3787 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3788 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3789 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3790 <item> <p><tt>debian/shlibs.local</tt></p></item>
3792 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3793 creating a binary package.</p>
3796 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3800 <prgn>dpkg-shlibdeps</prgn>
3801 determines the shared libraries directly
3804 It used to do this by calling <prgn>ldd</prgn>, but it
3805 now calls <prgn>objdump</prgn> to do this. This
3806 requires a couple of changes in the way that packages
3810 A binary <tt>foo</tt> directly uses a library
3811 <tt>libbar</tt> if it is linked with that
3812 library. Other libraries that are needed by
3813 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3814 and the dynamic linker will load them automatically
3815 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3816 lists all of the libraries used, both directly and
3817 indirectly; but <prgn>objdump</prgn> only lists the
3818 directly linked libraries. A package only needs to
3819 depend on the libraries it is directly linked to,
3820 since the dependencies for those libraries should
3821 automatically pull in the other libraries.
3824 This change does mean a change in the way packages are
3825 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3826 only run on binaries. But since we will now rely on the
3827 libraries depending on the libraries they themselves
3828 need, the packages containing those libraries will
3829 need to run <prgn>dpkg-shlibdeps</prgn> on the
3833 A good example where this would help us is the current
3834 mess with multiple version of the <tt>mesa</tt>
3835 library. With the <prgn>ldd</prgn>-based system, every
3836 package that uses <tt>mesa</tt> needs to add a
3837 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3838 to handle the glide <tt>mesa</tt> variant. With an
3839 <prgn>objdump</prgn>-based system this isn't necessary
3840 anymore and would have saved everyone a lot of work.
3843 Another example: we could update <tt>libimlib</tt>
3844 with a new version that supports a new graphics format
3845 called dgf. If we use the old <prgn>ldd</prgn> method,
3846 every package that uses <tt>libimlib</tt> would need
3847 to be recompiled so it would also depend on
3848 <tt>libdgf</tt> or it wouldn't run due to missing
3849 symbols. However with the new system, packages using
3850 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3851 having the dependency on <tt>libdgf</tt> and wouldn't
3855 used by the compiled binaries and libraries passed through
3856 on its command line.
3860 For each shared library linked to,
3861 <prgn>dpkg-shlibdeps</prgn> needs to know
3862 <list compact="compact">
3863 <item><p>the package containing the library, and</p></item>
3864 <item><p>the library version number,</p></item>
3866 and it scans the following files in this order:
3867 <enumlist compact="compact">
3868 <item><p><tt>debian/shlibs.local</tt></p></item>
3869 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3870 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3871 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3876 <sect1><heading><em>Who</em> maintains the various
3877 <tt>shlibs</tt> files?
3881 <list compact="compact">
3883 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3888 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3889 - the maintainer of each package</p>
3893 <tt>/etc/dpkg/shlibs.override</tt> - the local
3894 system administrator</p>
3897 <p><tt>debian/shlibs.local</tt> - the maintainer of
3902 The <tt>shlibs.default</tt> file is managed by
3903 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3904 that are provided by <prgn>dpkg</prgn> are just there to
3905 fix things until the shared library packages all have
3906 <tt>shlibs</tt> files.
3910 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3911 the <tt>shlibs</tt> files
3914 <sect2><heading>If your package doesn't provide a shared
3919 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3920 <tt>debian/rules</tt> file. If your package contains
3921 only binaries (e.g. no scripts) use:
3923 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3925 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3926 done. If it does complain you might need to create your
3927 own <tt>debian/shlibs.local</tt> file.</p>
3930 <sect2><heading>If your package provides a shared library
3934 Create a <tt>debian/shlibs</tt> file and let
3935 <tt>debian/rules</tt> install it in the control area:
3937 install -m644 debian/shlibs debian/tmp/DEBIAN
3939 If your package contains additional binaries see above.
3944 <sect1><heading><em>How</em> to write
3945 <tt>debian/shlibs.local</tt>
3949 This file is intended only as a <em>temporary</em> fix if
3950 your binaries depend on a library which doesn't provide
3951 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3955 Let's assume you are packaging a binary <tt>foo</tt>. Your
3956 output in building the package might look like this.
3959 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3960 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3961 libc.so.6 => /lib/libc.so.6 (0x40114000)
3962 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3964 And when you ran <prgn>dpkg-shlibdeps</prgn>
3966 $ dpkg-shlibdeps -O foo
3967 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3968 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3969 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3971 The <prgn>foo</prgn> binary depends on the
3972 <prgn>libbar</prgn> shared library, but no package seems
3973 to provide a <tt>*.shlibs</tt> file in
3974 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3980 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3981 bar1: /usr/X11R6/lib/libbar.so.1.0
3982 $ dpkg -s bar1 | grep Version
3985 This tells us that the <prgn>bar1</prgn> package, version
3986 1.0-1 is the one we are using. Now we can create our own
3987 <tt>debian/shlibs.local</tt> to temporarily fix the above
3988 problem. Include the following line into your
3989 <tt>debian/shlibs.local</tt> file.
3991 libbar 1 bar1 (>= 1.0-1)
3993 Now your package build should work. As soon as the
3994 maintainer of <prgn>libbar1</prgn> provides a
3995 <tt>shlibs</tt> file, you can remove your
3996 <tt>debian/shlibs.local</tt> file.
4002 <chapt><heading>The Operating System</heading>
4006 <heading>File system hierarchy</heading>
4010 <heading>Linux File system Structure</heading>
4013 The location of all installed files and directories must
4014 comply with the Linux File system Hierarchy Standard
4015 (FHS). The latest version of this document can be found
4016 alongside this manual or on
4017 <url id="http://www.pathname.com/fhs/">.
4018 Specific questions about following the standard may be
4019 asked on <prgn>debian-devel</prgn>, or referred to Daniel
4020 Quinlan, the FHS coordinator, at
4021 <email>quinlan@pathname.com</email>.</p></sect1>
4025 <heading>Site-specific programs</heading>
4028 As mandated by the FHS, packages must not place any
4029 files in <tt>/usr/local</tt>, either by putting them in
4030 the file system archive to be unpacked by <prgn>dpkg</prgn>
4031 or by manipulating them in their maintainer scripts.</p>
4034 However, the package may create empty directories below
4035 <tt>/usr/local</tt> so that the system administrator knows
4036 where to place site-specific files. These directories
4037 should be removed on package removal if they are
4041 Note, that this applies only to directories <em>below</em>
4042 <tt>/usr/local</tt>, not <em>in</em>
4043 <tt>/usr/local</tt>. Packages must not create sub-directories
4044 in the directory <tt>/usr/local</tt> itself, except those listed in
4045 FHS, section 4.5. However, you may create directories
4046 below them as you wish. You must not remove any of the
4047 directories listed in 4.5, even if you created them.</p>
4050 Since <tt>/usr/local</tt> can be mounted read-only from a
4051 remote server, these directories must be created and
4052 removed by the <tt>postinst</tt> and <tt>prerm</tt>
4053 maintainer scripts. These scripts must not fail if either
4054 of these operations fail. (In the future, it will be
4055 possible to tell <prgn>dpkg</prgn> not to unpack files
4056 matching certain patterns, so that the directories can be
4057 included in the <tt>.deb</tt> packages and system
4058 administrators who do not wish these directories in
4059 /usr/local do not need to have them.)</p>
4062 For example, the <prgn>emacs</prgn> package will contain
4064 mkdir -p /usr/local/lib/emacs/site-lisp || true
4066 in the <tt>postinst</tt> script, and
4068 rmdir /usr/local/lib/emacs/site-lisp || true
4069 rmdir /usr/local/lib/emacs || true
4071 in the <tt>prerm</tt> script.</p>
4074 If you do create a directory in <tt>/usr/local</tt> for
4075 local additions to a package, you should ensure that
4076 settings in <tt>/usr/local</tt> take precedence over the
4077 equivalents in <tt>/usr</tt>.</p>
4080 However, because '/usr/local' and its contents are for
4081 exclusive use of the local administrator, a package must
4082 not rely on the presence or absence of files or
4083 directories in '/usr/local' for normal operation.</p>
4086 The <tt>/usr/local</tt> directory itself and all the
4087 subdirectories created by the package should (by default) have
4088 permissions 2775 (group-writable and set-group-id) and be
4089 owned by <tt>root.staff</tt>.</p>
4092 <heading>The system-wide mail directory</heading>
4094 The system-wide mail directory is <tt>/var/mail</tt>. This
4095 directory is part of the base system and should not owned
4096 by any particular mail agents. The use of the old
4097 location <tt>/var/spool/mail</tt> is deprecated, even
4098 though the spool may still be physically located there.
4099 To maintain partial upgrade compatibility for systems
4100 which have <tt>/var/spool/mail</tt> as their physical mail
4101 spool, packages using <tt>/var/mail</tt> must depend on
4102 either <package>libc6</package> (>= 2.1.3-13), or on
4103 <package>base-files</package> (>= 2.2.0), or on later
4104 versions of either one of these packages.
4113 <heading>Users and groups</heading>
4116 The Debian system can be configured to use either plain or
4117 shadow passwords.</p>
4120 Some user ids (UIDs) and group ids (GIDs) are reserved
4121 globally for use by certain packages. Because some packages
4122 need to include files which are owned by these users or
4123 groups, or need the ids compiled into binaries, these ids
4124 must be used on any Debian system only for the purpose for
4125 which they are allocated. This is a serious restriction, and
4126 we should avoid getting in the way of local administration
4127 policies. In particular, many sites allocate users and/or
4128 local system groups starting at 100.</p>
4131 Apart from this we should have dynamically allocated ids,
4132 which should by default be arranged in some sensible
4133 order--but the behavior should be configurable.</p>
4136 Packages other than <tt>base-passwd</tt> must not modify
4137 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4138 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4141 The UID and GID ranges are as follows:
4146 Globally allocated by the Debian project, the
4147 same on every Debian system. These ids will appear in
4148 the <tt>passwd</tt> and <tt>group</tt> files of all
4149 Debian systems, new ids in this range being added
4150 automatically as the <tt>base-passwd</tt> package is
4154 Packages which need a single statically allocated uid
4155 or gid should use one of these; their maintainers
4156 should ask the <tt>base-passwd</tt> maintainer for
4163 Dynamically allocated system users and groups.
4164 Packages which need a user or group, but can have this
4165 user or group allocated dynamically and differently on
4166 each system, should use `<tt>adduser --system</tt>' to
4167 create the group and/or user. <prgn>adduser</prgn>
4168 will check for the existence of the user or group, and
4169 if necessary choose an unused id based on the ranges
4170 specified in <tt>adduser.conf</tt>.</p></item>
4173 <tag>1000-29999:</tag>
4176 Dynamically allocated user accounts. By default
4177 <prgn>adduser</prgn> will choose UIDs and GIDs for
4178 user accounts in this range, though
4179 <tt>adduser.conf</tt> may be used to modify this
4183 <tag>30000-59999:</tag>
4185 <p>Reserved.</p></item>
4188 <tag>60000-64999:</tag>
4191 Globally allocated by the Debian project, but only
4192 created on demand. The ids are allocated centrally and
4193 statically, but the actual accounts are only created
4194 on users' systems on demand.</p>
4197 These ids are for packages which are obscure or which
4198 require many statically-allocated ids. These packages
4199 should check for and create the accounts in
4200 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4201 <prgn>adduser</prgn> if it has this facility) if
4202 necessary. Packages which are likely to require
4203 further allocations should have a `hole' left after
4204 them in the allocation, to give them room to
4208 <tag>65000-65533:</tag>
4210 <p>Reserved.</p></item>
4215 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4216 to the group `<tt>nogroup</tt>.'</p></item>
4222 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4223 because it is the error return sentinel value.</p>
4228 <sect id="sysvinit">
4229 <heading>System run levels</heading>
4232 <sect1 id="/etc/init.d">
4233 <heading>Introduction</heading>
4236 The <tt>/etc/init.d</tt> directory contains the scripts
4237 executed by <prgn>init</prgn> at boot time and when init
4238 state (or `runlevel') is changed (see <manref name="init"
4242 There are at least two different, yet functionally
4243 equivalent, ways of handling these scripts. For the sake
4244 of simplicity, this document describes only the symbolic
4245 link method. However, it must not be assumed by maintainer
4246 scripts that this method is being used, and any automated
4247 manipulation of the various runlevel behaviours by
4248 maintainer scripts must be performed using `update-rc.d'
4249 as described below and not by manually installing or
4250 removing symlinks. For information on the
4251 implementation details of the other method, implemented in
4252 the <tt>file-rc</tt> package, please refer to the
4253 documentation of that package.</p>
4256 These scripts are referenced by symbolic links in
4257 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4258 changing runlevels, <prgn>init</prgn> looks in the
4259 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4260 it should execute, where <var>n</var> is the runlevel that
4261 is being changed to, or `S' for the boot-up scripts.</p>
4264 The names of the links all have the form
4265 <tt>S<var>mm</var><var>script</var></tt> or
4266 <tt>K<var>mm</var><var>script</var></tt> where
4267 <var>mm</var> is a two-digit number and <var>script</var>
4268 is the name of the script (this should be the same as the
4269 name of the actual script in <tt>/etc/init.d</tt>.</p>
4272 When <prgn>init</prgn> changes runlevel first the targets
4273 of the links whose names starting with a <tt>K</tt> are
4274 executed, each with the single argument <tt>stop</tt>,
4275 followed by the scripts prefixed with an <tt>S</tt>, each
4276 with the single argument <tt>start</tt>. The <tt>K</tt>
4277 links are responsible for killing services and the
4278 <tt>S</tt> link for starting services upon entering the
4282 For example, if we are changing from runlevel 2 to
4283 runlevel 3, init will first execute all of the <tt>K</tt>
4284 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4285 all of the <tt>S</tt> prefixed scripts. The links
4286 starting with <tt>K</tt> will cause the referred-to file
4287 to be executed with an argument of <tt>stop</tt>, and the
4288 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4291 The two-digit number <var>mm</var> is used to decide which
4292 order to start and stop things in--low-numbered links have
4293 their scripts run first. For example, the <tt>K20</tt>
4294 scripts will be executed before the <tt>K30</tt> scripts.
4295 This is used when a certain service must be started before
4296 another. For example, the name server <prgn>bind</prgn>
4297 might need to be started before the news server
4298 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4299 access lists. In this case, the script that starts
4300 <prgn>bind</prgn> would have a lower number than the
4301 script that starts <prgn>inn</prgn> so that it runs first:
4310 <heading>Writing the scripts</heading>
4313 Packages that include daemons for system services should
4314 place scripts in <tt>/etc/init.d</tt> to start or stop
4315 services at boot time or during a change of runlevel.
4316 These scripts should be named
4317 <tt>/etc/init.d/<var>package</var></tt>, and they should
4318 accept one argument, saying what to do:
4321 <tag><tt>start</tt></tag>
4322 <item><p>start the service,</p></item>
4324 <tag><tt>stop</tt></tag>
4325 <item><p>stop the service,</p></item>
4327 <tag><tt>restart</tt></tag>
4328 <item><p>stop and restart the service,</p></item>
4330 <tag><tt>reload</tt></tag>
4331 <item><p>cause the configuration of the service to be
4332 reloaded without actually stopping and restarting
4333 the service,</p></item>
4335 <tag><tt>force-reload</tt></tag> <item><p>cause the
4336 configuration to be reloaded if the service supports
4337 this, otherwise restart the service.</p></item>
4340 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4341 <tt>force-reload</tt> options should be supported by all
4342 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4343 option is optional.</p>
4346 The <tt>init.d</tt> scripts should ensure that they will
4347 behave sensibly if invoked with <tt>start</tt> when the
4348 service is already running, or with <tt>stop</tt> when it
4349 isn't, and that they don't kill unfortunately-named user
4350 processes. The best way to achieve this is usually to use
4351 <prgn>start-stop-daemon</prgn>.</p>
4354 If a service reloads its configuration automatically (as
4355 in the case of <prgn>cron</prgn>, for example), the
4356 <tt>reload</tt> option of the <tt>init.d</tt> script
4357 should behave as if the configuration has been reloaded
4361 These scripts should not fail obscurely when the
4362 configuration files remain but the package has been
4363 removed, as configuration files remain on the system after
4364 the package has been removed. Only when <prgn>dpkg</prgn>
4365 is executed with the <tt>--purge</tt> option will
4366 configuration files be removed. In particular, the init
4367 script itself is usually a configuration file (see
4368 <ref id="init.d notes">), and will remain on the system if
4369 the package is removed but not purged. Therefore, you
4370 should include a <tt>test</tt> statement at the top of the
4373 test -f <var>program-executed-later-in-script</var> || exit 0
4377 Often there are some values in the `<tt>init.d</tt>'
4378 scripts that a system administrator will frequently want
4379 to change. While the scripts are frequently conffiles,
4380 modifying them requires that the administrator merge in
4381 their changes each time the package is upgraded and the
4382 conffile changes. To ease the burden on the system
4383 administrator, such configurable values should not be
4384 placed directly in the script. Instead, they should be
4385 placed in a file in `<tt>/etc/default</tt>', which
4386 typically will have the same base name as the
4387 `<tt>init.d</tt>' script. This extra file can be sourced
4388 by the script when the script runs. It must contain only
4389 variable settings and comments.
4393 To ensure that vital configurable values are always
4394 available, the `<tt>init.d</tt>' script should set default
4395 values for each of the shell variables it uses before
4396 sourcing the <tt>/etc/default/</tt> file. Also, since the
4397 `<tt>/etc/default/</tt>' file is often a conffile, the
4398 `<tt>init.d</tt>' script must behave sensibly without
4399 failing if it is deleted.
4405 <heading>Managing the links</heading>
4408 The program <prgn>update-rc.d</prgn> is provided to make
4409 it easier for package maintainers to arrange for the
4410 proper creation and removal of
4411 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4412 functional equivalent if another method is being used.
4413 This may be used by maintainers in their packages'
4414 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4417 You must use this script to make changes to
4418 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4419 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4420 in the actual archive or manually create or remove the
4421 symbolic links in maintainer scripts. (The latter will
4422 fail if an alternative method of maintaining runlevel
4423 information is being used.)</p>
4426 By default <prgn>update-rc.d</prgn> will start services in
4427 each of the multi-user state runlevels (2, 3, 4, and 5)
4428 and stop them in the halt runlevel (0), the single-user
4429 runlevel (1) and the reboot runlevel (6). The system
4430 administrator will have the opportunity to customize
4431 runlevels by either running <prgn>update-rc.d</prgn>, by
4432 simply adding, moving, or removing the symbolic links in
4433 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4434 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4435 <tt>file-rc</tt> method is being used.</p>
4438 To get the default behavior for your package, put in your
4439 <tt>postinst</tt> script
4441 update-rc.d <var>package</var> defaults >/dev/null
4443 and in your <tt>postrm</tt>
4445 if [ purge = "$1" ]; then
4446 update-rc.d <var>package</var> remove >/dev/null
4451 This will use a default sequence number of 20. If it does
4452 not matter when or in which order the script is run, use
4453 this default. If it does, then you should talk to the
4454 maintainer of the <prgn>sysvinit</prgn> package or post to
4455 <tt>debian-devel</tt>, and they will help you choose a
4459 For more information about using <tt>update-rc.d</tt>,
4460 please consult its manpage <manref name="update-rc.d"
4461 section="8">.</p></sect1>
4465 <heading>Boot-time initialization</heading>
4468 There used to be another directory, <tt>/etc/rc.boot</tt>,
4469 which contained scripts which were run once per machine
4470 boot. This has been deprecated in favour of links from
4471 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4472 described in <ref id="/etc/init.d">. Packages must not
4473 place files in <tt>/etc/rc.boot</tt>.</p>
4475 <sect1 id="init.d notes">
4476 <heading>Notes</heading>
4479 <em>Do not</em> include the
4480 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4481 <tt>.deb</tt> file system archive! <em>This will cause
4482 problems!</em> You must create them with
4483 <prgn>update-rc.d</prgn>, as above.</p>
4486 <em>Do not</em> include the
4487 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4488 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4489 problems!</em> You should, however, treat the
4490 <tt>/etc/init.d</tt> scripts as configuration files,
4491 either by marking them as conffiles or managing them
4492 correctly in the maintainer scripts (see
4493 <ref id="config files">). (This is important since we want
4494 to give the local system administrator the chance to adapt
4495 the scripts to the local system--e.g., to disable a
4496 service without de-installing the package, or to specify
4497 some special command line options when starting a
4498 service--while making sure her changes aren't lost during
4499 the next package upgrade.)</p>
4503 <heading>Example</heading>
4506 The <prgn>bind</prgn> DNS (nameserver) package wants to
4507 make sure that the nameserver is running in multiuser
4508 runlevels, and is properly shut down with the system. It
4509 puts a script in <tt>/etc/init.d</tt>, naming the script
4510 appropriately <tt>bind</tt>. As you can see, the script
4511 interprets the argument <tt>reload</tt> to send the
4512 nameserver a <tt>HUP</tt> signal (causing it to reload its
4513 configuration); this way the user can say
4514 <tt>/etc/init.d/bind reload</tt> to reload the name
4515 server. The script has one configurable value, which can
4516 be used to pass parameters to the named program at
4524 # Original version by Robert Leslie
4525 # <rob@mars.org>, edited by iwj and cs
4527 test -x /usr/sbin/named || exit 0
4529 # Source defaults file.
4531 if [ -f /etc/default/bind ]; then
4538 echo -n "Starting domain name service: named"
4539 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4544 echo -n "Stopping domain name service: named"
4545 start-stop-daemon --stop --quiet \
4546 --pidfile /var/run/named.pid --exec /usr/sbin/named
4550 echo -n "Restarting domain name service: named"
4551 start-stop-daemon --stop --quiet \
4552 --pidfile /var/run/named.pid --exec /usr/sbin/named
4553 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4557 force-reload|reload)
4558 echo -n "Reloading configuration of domain name service: named"
4559 start-stop-daemon --stop --signal 1 --quiet \
4560 --pidfile /var/run/named.pid --exec /usr/sbin/named
4564 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4574 Complementing the above init script is a file
4575 '<tt>/etc/default/bind</tt>', which contains configurable
4576 parameters used by the script.
4580 # Specified parameters to pass to named. See named(8).
4581 # You may uncomment the following line, and edit to taste.
4587 Another example on which to base your <tt>/etc/init.d</tt>
4588 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4591 If this package is happy with the default setup from
4592 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4593 and having named running in all runlevels, it can say in
4594 its <tt>postinst</tt>:
4596 update-rc.d bind defaults >/dev/null
4598 And in its <tt>postrm</tt>, to remove the links when the
4601 if [ purge = "$1" ]; then
4602 update-rc.d bind remove >/dev/null
4608 <heading>Cron jobs</heading>
4611 Packages must not modify the configuration file
4612 <tt>/etc/crontab</tt>, and they must not modify the files in
4613 <tt>/var/spool/cron/crontabs</tt>.</p>
4616 If a package wants to install a job that has to be executed
4617 via cron, it should place a file with the name of the
4618 package in one of the following directories:
4624 As these directory names imply, the files within them are
4625 executed on a daily, weekly, or monthly basis,
4626 respectively. The exact times are listed in
4627 <tt>/etc/crontab</tt>.</p>
4630 All files installed in any of these directories must be
4631 scripts (shell scripts, Perl scripts, etc.) so that they can
4632 easily be modified by the local system administrator. In
4633 addition, they should be treated as configuration files.</p>
4636 If a certain job has to be executed more frequently than
4637 daily, the package should install a file
4638 <tt>/etc/cron.d/<var>package</var></tt>. This file uses
4639 the same syntax as <tt>/etc/crontab</tt> and is processed by
4640 <prgn>cron</prgn> automatically. The file must also be
4641 treated as a configuration file. (Note, that entries in the
4642 <tt>/etc/cron.d</tt> directory are not handled by
4643 <prgn>anacron</prgn>. Thus, you should only use this
4644 directory for jobs which may be skipped if the system is not
4648 The scripts or crontab entries in these directories should
4649 check if all necessary programs are installed before they
4650 try to execute them. Otherwise, problems will arise when a
4651 package was removed but not purged since configuration files
4652 are kept on the system in this situation.</p>
4656 <heading>Console messages</heading>
4659 This section describes different formats for messages
4660 written to standard output by the <tt>/etc/init.d</tt>
4661 scripts. The intent is to improve the consistency of
4662 Debian's startup and shutdown look and feel.</p>
4665 Please look very careful at the details. We want to get the
4666 messages to look exactly the same way concerning spaces,
4667 punctuation, and case of letters.</p>
4670 Here is a list of overall rules that you should use when you
4671 create output messages. They can be useful if you have a
4672 non-standard message that isn't covered in the sections
4679 Every message should cover one line, start with a
4680 capital letter and end with a period `.'.</p></item>
4685 If you want to express that the computer is working on
4686 something (performing a specific task, not starting or
4687 stopping a program), we use an ``ellipsis'', namely
4688 three dots `...'. Note that we don't insert spaces in
4689 front of or behind the dots. If the task has been
4690 completed we write `done.' and a line feed.</p></item>
4695 Design your messages as if the computer is telling you
4696 what he is doing (let him be polite :-) but don't
4697 mention ``him'' directly. For example, if you think
4700 I'm starting network daemons: nfsd mountd.
4704 Starting network daemons: nfsd mountd.
4705 </example></p></item>
4709 The following formats should be used</p>
4714 <p>when daemons get started.</p>
4717 Use this format if your script starts one or more
4718 daemons. The output should look like this (a single
4719 line, no leading spaces):
4721 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4723 The <description> should describe the subsystem
4724 the daemon or set of daemons are part of, while
4725 <daemon-1> up to <daemon-n> denote each
4726 daemon's name (typically the file name of the
4730 For example, the output of /etc/init.d/lpd would look like:
4732 Starting printer spooler: lpd.
4736 This can be achieved by saying
4738 echo -n "Starting printer spooler: lpd"
4739 start-stop-daemon --start --quiet lpd
4742 in the script. If you have more than one daemon to
4743 start, you should do the following:
4745 echo -n "Starting remote file system services:"
4746 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4747 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4748 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4751 This makes it possible for the user to see what takes
4752 so long and when the final daemon has been
4753 started. You should be careful where to put spaces: In the
4754 example above the system administrator can easily
4755 comment out a line if he don't wants to start a
4756 specific daemon, while the displayed message still
4757 looks good.</p></item>
4761 <p>when something needs to be configured.</p>
4764 If you have to set up different parameters of the
4765 system upon boot up, you should use this format:
4767 Setting <parameter> to `<value>'.
4771 You can use the following echo statement to get the quotes right:
4773 echo "Setting DNS domainname to \`"value"'."
4777 Note that the left quotation mark (`) is different
4778 from the right (').</p></item>
4781 <p>when a daemon is stopped.</p>
4784 When you stop a daemon you should issue a message
4785 similar to the startup message, except that `Starting'
4786 is replaced with `Stopping'.</p>
4789 So stopping the printer daemon will like like this:
4791 Stopping printer spooler: lpd.
4792 </example></p></item>
4795 <p>when something is executed.</p>
4798 There are several examples where you have to run a
4799 program at system startup or shutdown to perform a
4800 specific task. For example, setting the system's clock
4801 via `netdate' or killing all processes when the system
4802 comes down. Your message should like this:
4804 Doing something very useful...done.
4806 You should print the `done.' right after the job has been completed,
4807 so that the user gets informed why he has to wait. You can get this
4810 echo -n "Doing something very useful..."
4814 in your script.</p></item>
4817 <p>when the configuration is reloaded.</p>
4820 When a daemon is forced to reload its configuration
4821 files you should use the following format:
4823 Reloading <daemon's-name> configuration...done.
4824 </example></p></item>
4827 <p>when none of the above rules apply.</p>
4830 If you have to print a message that doesn't fit into
4831 the styles described above, you can use something
4832 appropriate, but please have a look at the overall
4833 rules listed above.</p></item>
4838 <heading>Menus</heading>
4841 Menu entries should follow the current menu policy as
4842 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4843 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4844 or your local mirror. In addition, it is included in the
4845 <tt>debian-policy</tt> package.
4849 The Debian <tt>menu</tt> packages provides a unique
4850 interface between packages providing applications and
4851 documents, and <em>menu programs</em> (either X window
4852 managers or text-based menu programs as
4853 <prgn>pdmenu</prgn>).</p>
4856 All packages that provide applications that need not be
4857 passed any special command line arguments for normal
4858 operation should register a menu entry for those
4859 applications, so that users of the <tt>menu</tt> package
4860 will automatically get menu entries in their window
4861 managers, as well in shells like <tt>pdmenu</tt>.</p>
4864 Please refer to the <em>Debian Menu System</em> document
4865 that comes with the <tt>menu</tt> package for information
4866 about how to register your applications and web
4872 <heading>Multimedia handlers</heading>
4875 Packages which provide the ability to view/show/play,
4876 compose, edit or print MIME types should register themselves
4877 as such following the current MIME support policy as defined
4878 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4879 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4880 or your local mirror. In addition, it is included in the
4881 <tt>debian-policy</tt> package.
4885 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4886 mechanism for encoding files and data streams and providing
4887 meta-information about them, in particular their type (e.g.
4888 audio or video) and format (e.g. PNG, HTML, MP3).
4892 Registration of MIME type handlers allows programs like mail
4893 user agents and web browsers to to invoke these handlers to
4894 view, edit or display MIME types they don't support
4900 <heading>Keyboard configuration</heading>
4903 To achieve a consistent keyboard configuration (i.e., all
4904 applications interpret a keyboard event the same way) all
4905 programs in the Debian distribution must be configured to
4906 comply with the following guidelines.</p>
4909 Here is a list that contains certain keys and their interpretation:
4912 <tag><tt><--</tt></tag>
4913 <item><p>delete the character to the left of the cursor</p></item>
4915 <tag><tt>Delete</tt></tag>
4916 <item><p>delete the character to the right of the cursor</p></item>
4918 <tag><tt>Control+H</tt></tag>
4919 <item><p>emacs: the help prefix</p></item>
4922 The interpretation of any keyboard events should be independent
4923 of the terminal that's used, be it a virtual console, an X
4924 terminal emulator, an rlogin/telnet session, etc.</p>
4927 The following list explains how the different programs
4928 should be set up to achieve this:</p>
4931 <list compact="compact">
4932 <item><p>`<tt><--</tt>' generates KB_Backspace in
4935 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4939 X translations are set up to make KB_Backspace
4940 generate ASCII DEL, and to make KB_Delete generate
4941 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4942 the `delete character' key). This must be done by
4943 loading the resources using xrdb on all local X
4944 displays, not using the application defaults, so that
4945 the translation resources used correspond to the
4946 xmodmap settings.</p></item>
4950 The Linux console is configured to make
4951 `<tt><--</tt>' generate DEL, and `Delete' generate
4952 <tt>ESC [ 3 ~</tt> (this is the case at the
4956 X applications are configured so that Backspace
4957 deletes left, and Delete deletes right. Motif
4958 applications already work like this.</p></item>
4960 <item><p>stty erase <tt>^?</tt> .</p></item>
4963 The `xterm' terminfo entry should have <tt>ESC [ 3
4964 ~</tt> for kdch1, just like TERM=linux and
4965 TERM=vt220.</p></item>
4968 Emacs is programmed to map KB_Backspace or the `stty
4969 erase' character to delete-backward-char, and
4970 KB_Delete or kdch1 to delete-forward-char, and
4971 <tt>^H</tt> to help as always.</p></item>
4974 Other applications use the `stty erase' character and
4975 kdch1 for the two delete keys, with ASCII DEL being
4976 `delete previous character' and kdch1 being `delete
4977 character under cursor'.</p></item>
4981 This will solve the problem except for:</p>
4984 <list compact="compact">
4986 Some terminals have a <tt><--</tt> key that cannot
4987 be made to produce anything except <tt>^H</tt>. On
4988 these terminals Emacs help will be unavailable on
4989 <tt>^H</tt> (assuming that the `stty erase' character
4990 takes precedence in Emacs, and has been set
4991 correctly). M-x help or F1 (if available) can be used
4995 Some operating systems use <tt>^H</tt> for stty erase.
4996 However, modern telnet versions and all rlogin
4997 versions propagate stty settings, and almost all UNIX
4998 versions honour stty erase. Where the stty settings
4999 are not propagated correctly things can be made to
5000 work by using stty manually.</p></item>
5003 Some systems (including previous Debian versions) use
5004 xmodmap to arrange for both <tt><--</tt> and Delete
5005 to generate KB_Delete. We can change the behavior
5006 of their X clients via the same X resources that we
5007 use to do it for our own, or have our clients be
5008 configured via their resources when things are the
5009 other way around. On displays configured like this
5010 Delete will not work, but <tt><--</tt>
5014 Some operating systems have different kdch1 settings
5015 in their terminfo for xterm and others. On these
5016 systems the Delete key will not work correctly when
5017 you log in from a system conforming to our policy, but
5018 <tt><--</tt> will.</p></item>
5025 <heading>Environment variables</heading>
5028 A program must not depend on environment variables to get
5029 reasonable defaults. (That's because these environment
5030 variables would have to be set in a system-wide
5031 configuration file like /etc/profile, which is not supported
5035 If a program usually depends on environment variables for its
5036 configuration, the program should be changed to fall back to
5037 a reasonable default configuration if these environment
5038 variables are not present. If this cannot be done easily
5039 (e.g., if the source code of a non-free program is not
5040 available), the program must be replaced by a small
5041 `wrapper' shell script which sets the environment variables
5042 if they are not already defined, and calls the original program.</p>
5045 Here is an example of a wrapper script for this purpose:
5049 BAR=${BAR:-/var/lib/fubar}
5051 exec /usr/lib/foo/foo "$@"
5055 Furthermore, as <tt>/etc/profile</tt> is a configuration
5056 file of the <prgn>base-files</prgn> package, other packages must not
5057 put any environment variables or other commands into that
5062 <heading>Files</heading>
5066 <heading>Binaries</heading>
5069 Two different packages must not install programs with
5070 different functionality but with the same filenames. (The
5071 case of two programs having the same functionality but
5072 different implementations is handled via `alternatives.')
5073 If this case happens, one of the programs must be
5074 renamed. The maintainers should report this to the
5075 developers' mailing and try to find a consensus about
5076 which package will have to be renamed. If a consensus can
5077 not be reached, <em>both</em> programs must be
5081 Generally the following compilation parameters should be used:
5084 CFLAGS = -O2 -Wall # sane warning options vary between programs
5086 install -s # (or use strip on the files in debian/tmp)
5090 Note that by default all installed binaries should be stripped,
5091 either by using the <tt>-s</tt> flag to
5092 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5093 the binaries after they have been copied into
5094 <tt>debian/tmp</tt> but before the tree is made into a
5098 The <tt>-N</tt> flag should not be used. On a.out systems
5099 it may have been useful for some very small binaries, but
5100 for ELF it has no good effect.</p>
5103 Debugging symbols are useful for error diagnosis,
5104 investigation of core dumps (which may be submitted by users
5105 in bug reports), or testing and developing the
5106 software. Therefore it is recommended to support building
5107 the package with debugging information through the following
5108 interface: If the environment variable
5109 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5110 <tt>debug</tt>, compile the software with debugging
5111 information (usually this involves adding the <tt>-g</tt>
5112 flag to <tt>CFLAGS</tt>). This allows the generation of a
5113 build tree with debugging information. If the environment
5114 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5115 <tt>nostrip</tt>, do not strip the files at installation
5116 time. This allows one to generate a package with debugging
5117 information included. The following makefile snippet is only
5118 an example of how one may test for either condition:
5121 Rationale: Building by default with -g causes more
5122 wasted CPU cycles since the information is stripped away
5123 anyway. The package can by default build without -g if
5124 it also provides a mechanism to easily be rebuilt with
5125 debugging information. This can be done by providing a
5126 "build-debug" make target, or allowing the user to
5127 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5128 compiling that package.
5130 <p>Now this has several added benefits:
5134 It is actually easier to build debugging bins and
5135 libraries this way (no more editing debian/rules
5136 or similar) since it provides a documented way of
5137 getting this type of build.</p>
5141 There will be much less wasted CPU time for the
5142 autobuilders since not having debugging
5143 information (and hence also not having to strip
5144 it) will increase the speed of compiles. This
5145 skips an entire pass of the compiler.
5156 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5157 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5158 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5159 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5161 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5164 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5165 INSTALL_PROGRAM += -s
5169 Please note that the above example is merely informative,
5170 and is not a policy mandate. You may have to massage this
5171 example in order to make it work for your package.
5176 It is up to the package maintainer to decide what
5177 compilation options are best for the package. Certain
5178 binaries (such as computationally-intensive programs) will
5179 function better with certain flags (<tt>-O3</tt>, for
5180 example); feel free to use them. Please use good judgment
5181 here. Don't use flags for the sake of it; only use them
5182 if there is good reason to do so. Feel free to override
5183 the upstream author's ideas about which compilation
5184 options are best--they are often inappropriate for our
5185 environment.</p></sect>
5189 <heading>Libraries</heading>
5192 All libraries must have a shared version in the lib
5193 package and a static version in the lib-dev package. The
5194 shared version must be compiled with <tt>-fPIC</tt>, and
5195 the static version must not be. In other words, each
5196 <tt>*.c</tt> file will need to be compiled twice.</p>
5199 You must specify the gcc option <tt>-D_REENTRANT</tt>
5200 when building a library (either static or shared) to make
5201 the library compatible with LinuxThreads.</p>
5204 Note that all installed shared libraries should be
5207 strip --strip-unneeded <your-lib>
5209 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5210 only the symbols which aren't needed for relocation
5211 processing.) Shared libraries can function perfectly well
5212 when stripped, since the symbols for dynamic linking are
5213 in a separate part of the ELF object file.</p>
5216 Note that under some circumstances it may be useful to
5217 install a shared library unstripped, for example when
5218 building a separate package to support debugging.
5222 An ever increasing number of packages are using libtool to
5223 do their linking. The latest GNU libtools (>= 1.3a) can take
5224 advantage of the metadata in the installed libtool archive
5225 files (`*.la'). The main advantage of libtool's .la files is
5226 that it allows libtool to store and subsequently access
5227 metadata with respect to the libraries it builds. libtool
5228 will search for those files, which contain a lot of useful
5229 information about a library (e.g. dependency libraries for
5230 static linking). Also, they're <em>essential</em> for
5231 programs using libltdl.
5235 Certainly libtool is fully capable of linking against shared
5236 libraries which don't have .la files, but being a mere shell
5237 script it can add considerably to the build time of a
5238 libtool using package if that shell-script has to derive all
5239 this information from first principles for each library every
5240 time it is linked. With the advent of libtool-1.4 (and to a
5241 lesser extent libtool-1.3), the .la files will also store
5242 information about inter-library dependencies which cannot
5243 necessarily be derived after the .la file is deleted.
5247 Packages that use libtool to create shared libraries should
5248 include the <em>.la</em> files in the <em>-dev</em>
5249 packages, with the exception that if the package relies on
5250 libtool's <em>libltdl</em> library, in which case the .la
5251 files must go in the run-time library package. This is a
5252 good idea in general, and especially for static linking
5257 You must make sure that you use only released versions of
5258 shared libraries to build your packages; otherwise other
5259 users will not be able to run your binaries
5260 properly. Producing source packages that depend on
5261 unreleased compilers is also usually a bad
5268 <heading>Shared libraries</heading>
5271 Packages involving shared libraries should be split up
5272 into several binary packages.</p>
5275 For a straightforward library which has a development
5276 environment and a runtime kit including just shared
5277 libraries you need to create two packages:
5278 <tt><var>libraryname</var><var>soname</var></tt>
5279 (<var>soname</var> is the shared object name of the shared
5280 library--it's the thing that has to match exactly between
5281 building an executable and running it for the dynamic
5282 linker to be able run the program; usually the
5283 <var>soname</var> is the major number of the library) and
5284 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5287 If you prefer only to support one development version at a
5288 time you may name the development package
5289 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5290 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5291 ensure that the user only installs one development version
5292 at a time (after all, different development versions are
5293 likely to have the same header files in them, causing a
5294 filename clash if both are installed). Typically the
5295 development version should also have an exact version
5296 dependency on the runtime library, to make sure that
5297 compilation and linking happens correctly.</p>
5300 Packages which use the shared library should have a
5301 dependency on the name of the shared library package,
5302 <tt><var>libraryname</var><var>soname</var></tt>. When
5303 the <var>soname</var> changes you can have both versions
5304 of the library installed while moving from the old library
5308 If your package has some run-time support programs which
5309 use the shared library you must not put them in
5310 the shared library package. If you do that then you won't
5311 be able to install several versions of the shared library
5312 without getting filename clashes. Instead, either create
5313 a third package for the runtime binaries (this package
5314 might typically be named
5315 <tt><var>libraryname</var>-runtime</tt>--note the absence
5316 of the <var>soname</var> in the package name) or if the
5317 development package is small include them in there.</p>
5320 If you have several shared libraries built from the same
5321 source tree you may lump them all together into a single
5322 shared library package, provided that you change all their
5323 <var>soname</var>s at once (so that you don't get filename
5324 clashes if you try to install different versions of the
5325 combined shared libraries package).</p>
5328 You should follow the directions in the <em>Debian Packaging
5329 Manual</em> (or other documentation of the Debian
5330 packaging tools) for putting the shared library in its
5331 package, and you must include a <tt>shlibs</tt> control area
5332 file with details of the dependencies for packages which use
5336 Shared libraries should not be installed
5337 executable, since <prgn>ld.so</prgn> does not require this
5338 and trying to execute a shared library results in a core
5343 <heading>Scripts</heading>
5346 All command scripts, including the package maintainer
5347 scripts inside the package and used by <prgn>dpkg</prgn>,
5348 should have a <tt>#!</tt> line naming the shell to be used
5349 to interpret them.</p>
5352 In the case of Perl scripts this should be
5353 <tt>#!/usr/bin/perl</tt>.</p>
5356 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5357 should almost certainly start with <tt>set -e</tt> so that
5358 errors are detected. Every script should use
5359 <tt>set -e</tt> or check the exit status of <em>every</em>
5363 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5364 symbolic link to any POSIX compatible shell, if <tt>echo
5365 -n</tt> does not generate a newline.
5368 Debian policy specifies POSIX behavior for /bin/sh, but
5369 echo -n has widespread use in the Linux community
5370 (including especially debian policy, the linux kernel
5371 source, many debian scripts, etc.). This echo -n
5372 mechanism is valid but not required under POSIX, hence
5373 this explicit addition. Also, rumour has it that this
5374 shall be mandated under the LSB anyway.
5378 specifying `<tt>/bin/sh</tt>' as interpreter should only
5379 use POSIX features. If a script requires non-POSIX
5380 features from the shell interpreter, the appropriate shell
5381 must be specified in the first line of the script (e.g.,
5382 `<tt>#!/bin/bash</tt>') and the package must depend on the
5383 package providing the shell (unless the shell package is
5384 marked `Essential', e.g., in the case of
5389 You may wish to restrict your script to POSIX features when possible so
5390 that it may use <tt>/bin/sh</tt> as its interpreter. If
5391 your script works with <prgn>ash</prgn>, it's probably
5392 POSIX compliant, but if you are in doubt, use
5393 <tt>/bin/bash</tt>.</p>
5396 Perl scripts should check for errors when making any
5397 system calls, including <tt>open</tt>, <tt>print</tt>,
5398 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5401 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5402 as scripting languages. See <em>Csh Programming
5403 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5404 FAQs. It can be found on
5405 <url id="http://language.perl.com/versus/csh.whynot">, or
5406 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5407 or even on <ftpsite>ftp.cpan.org</ftpsite>
5408 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5409 If an upstream package comes with <prgn>csh</prgn> scripts
5410 then you must make sure that they start with
5411 <tt>#!/bin/csh</tt> and make your package depend on the
5412 <prgn>c-shell</prgn> virtual package.</p>
5415 Any scripts which create files in world-writeable
5416 directories (e.g., in <tt>/tmp</tt>) must use a
5417 mechanism which will fail if a file with the same name
5421 The Debian base distribution provides the
5422 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5423 for use by scripts for this purpose.</p></sect>
5427 <heading>Symbolic links</heading>
5430 In general, symbolic links within a top-level directory
5431 should be relative, and symbolic links pointing from one
5432 top-level directory into another should be absolute. (A
5433 top-level directory is a sub-directory of the root
5437 In addition, symbolic links should be specified as short
5438 as possible, i.e., link targets like `foo/../bar' are
5442 Note that when creating a relative link using
5443 <prgn>ln</prgn> it is not necessary for the target of the
5444 link to exist relative to the working directory you're
5445 running <prgn>ln</prgn> from; nor is it necessary to
5446 change directory to the directory where the link is to be
5447 made. Simply include the string that should appear as the
5448 target of the link (this will be a pathname relative to
5449 the directory in which the link resides) as the first
5450 argument to <prgn>ln</prgn>.</p>
5453 For example, in your <prgn>Makefile</prgn> or
5454 <tt>debian/rules</tt>, do things like:
5456 ln -fs gcc $(prefix)/bin/cc
5457 ln -fs gcc debian/tmp/usr/bin/cc
5458 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5459 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5463 A symbolic link pointing to a compressed file should
5464 always have the same file extension as the referenced
5465 file. (For example, if a file `<tt>foo.gz</tt>' is
5466 referenced by a symbolic link, the filename of the link
5467 has to end with `<tt>.gz</tt>' too, as in
5468 `bar.gz.')</p></sect>
5472 <heading>Device files</heading>
5475 Packages must not include device files in the package file
5479 If a package needs any special device files that are not
5480 included in the base system, it must call
5481 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5482 after asking the user for permission to do so.</p>
5485 Packages must not remove any device files in the
5486 <tt>postrm</tt> or any other script. This is left to the
5487 system administrator.</p>
5490 Debian uses the serial devices
5491 <tt>/dev/ttyS*</tt>. Programs using the old
5492 <tt>/dev/cu*</tt> devices should be changed to use
5493 <tt>/dev/ttyS*</tt>.</p>
5496 <sect id="config files">
5497 <heading>Configuration files</heading>
5499 <heading>Definitions</heading>
5502 <tag>configuration file</tag>
5504 A file that affects the operation of program, or
5505 provides site- or host-specific information, or
5506 otherwise customizes the behavior of program.
5507 Typically, configuration files are intended to be
5508 modified by the system administrator (if needed or
5509 desired) to conform to local policy or provide more
5510 useful site-specific behavior.</p>
5513 <tag><tt>conffile</tt></tag>
5515 A file listed in a package's <tt>conffiles</tt>
5516 file, and is treated specially by <prgn>dpkg</prgn>
5517 (see the <em>Debian Packaging Manual</em>).</p>
5523 The distinction between these two is important; they are
5524 not interchangeable concepts. Almost all
5525 <tt>conffiles</tt> are configuration files, but many
5526 configuration files are not <tt>conffiles</tt>.</p>
5529 Note that a script that embeds configuration information
5530 (such as most of the files in <tt>/etc/init.d</tt> and
5531 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5532 configuration file and should be treated as such.</p>
5536 <heading>Location</heading>
5538 Any configuration files created or used by your package
5539 must reside in <tt>/etc</tt>. If there are several you
5540 should consider creating a subdirectory of <tt>/etc</tt>
5541 named after your package.</p>
5544 If your package creates or uses configuration files
5545 outside of <tt>/etc</tt>, and it is not feasible to modify
5546 the package to use the <tt>/etc</tt>, you should still put
5547 the files in <tt>/etc</tt> and create symbolic links to
5548 those files from the location that the package
5553 <heading>Behavior</heading>
5555 Configuration file handling must conform to the following
5559 <p>local changes must be preserved during a package
5563 <p>configuration files must be preserved when the
5564 package is removed, and only deleted when the
5565 package is purged.</p>
5570 The easy way to achieve this behavior is to make the
5571 configuration file a <tt>conffile</tt>. This is
5572 appropriate only if it is possible to distribute a default
5573 version that will work for most installations, although
5574 some system administrators may choose to modify it. This
5575 implies that the default version will be part of the
5576 package distribution, and must not be modified by the
5577 maintainer scripts during installation (or at any other
5582 In order to ensure that local changes are preserved
5583 correctly, no package may contain or make hard links to
5587 Rationale: There are two problems with hard links.
5588 The first is that some editors break the link while
5589 editing one of the files, so that the two files may
5590 unwittingly become different. The second is that
5591 <prgn>dpkg</prgn> might break the hard link while
5592 upgrading <tt>conffile</tt>s.
5598 The other way to do it is via the maintainer scripts.
5599 In this case, the configuration file must not be listed as
5600 a <tt>conffile</tt> and must not be part of the package
5601 distribution. If the existence of a file is required for
5602 the package to be sensibly configured it is the
5603 responsibility of the package maintainer to write scripts
5604 which correctly create, update, maintain and
5605 remove-on-purge the file. These scripts must be idempotent
5606 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5607 re-run them due to errors during installation or removal),
5608 must cope with all the variety of ways <prgn>dpkg</prgn>
5609 can call maintainer scripts, must not overwrite or
5610 otherwise mangle the user's configuration without asking,
5611 must not ask unnecessary questions (particularly during
5612 upgrades), and otherwise be good citizens.</p>
5615 The scripts are not required to configure every possible option for
5616 the package, but only those necessary to get the package
5617 running on a given system. Ideally the sysadmin should not
5618 have to do any configuration other than that done
5619 (semi-)automatically by the <tt>postinst</tt> script.</p>
5622 A common practice is to create a script called
5623 <tt><var>package</var>-configure</tt> and have the
5624 package's <tt>postinst</tt> call it if and only if the
5625 configuration file does not already exist. In certain
5626 cases it is useful for there to be an example or template
5627 file which the maintainer scripts use. Such files should
5628 be in <tt>/usr/share/<package></tt> or
5629 <tt>/usr/lib/<package></tt> with a symbolic link
5630 from <tt>/usr/share/doc/<package>/examples</tt>
5631 if they are examples, and should be
5632 perfectly ordinary <prgn>dpkg</prgn>-handled files
5633 (<em>not</em> <tt>conffiles</tt>).
5637 These two styles of configuration file handling must
5638 not be mixed, for that way lies madness:
5639 <prgn>dpkg</prgn> will ask about overwriting the file
5640 every time the package is upgraded.</p>
5645 <heading>Sharing configuration files</heading>
5647 Packages which specify the same file as
5648 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5653 The maintainer scripts must not alter the conffile of
5654 <em>any</em> package, including the one the scripts belong
5658 If two or more packages use the same configuration file
5659 and it is reasonable for both to be installed at the same
5660 time, one of these packages must be defined as
5661 <em>owner</em> of the configuration file, i.e., it will be
5662 the package to list that distributes the file and lists it
5663 as a <tt>conffile</tt>. Other packages that use the
5664 configuration file must depend on the owning package if
5665 they require the configuration file to operate. If the
5666 other package will use the configuration file if present,
5667 but is capable of operating without it, no dependency need
5671 If it is desirable for two or more related packages to
5672 share a configuration file <em>and</em> for all of the
5673 related packages to be able to modify that configuration
5674 file, then the following should be done:
5678 have one of the related packages (the "core"
5679 package) manage the configuration file with
5680 maintainer scripts as described in the previous
5684 the core package should also provide a program that
5685 the other packages may use to modify the
5686 configuration file.</p>
5690 the related packages must use the provided program
5691 to make any modifications to the configuration file.
5692 They should either depend on the core package to
5693 guarantee that the configuration modifier program is
5694 available or accept gracefully that they cannot
5695 modify the configuration file if it is not.</p>
5700 Sometimes it's appropriate to create a new package which
5701 provides the basic infrastructure for the other packages
5702 and which manages the shared configuration files. (Check
5703 out the <tt>sgml-base</tt> package as an example.)</p>
5707 <heading>User configuration files ("dotfiles")</heading>
5710 Files in <tt>/etc/skel</tt> will automatically be copied
5711 into new user accounts by <prgn>adduser</prgn>. They
5712 should not be referenced there by any program.</p>
5715 Therefore, if a program needs a dotfile to exist in
5716 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5717 should be installed in <tt>/etc/skel</tt> (and listed in
5718 conffiles, if it is not generated and modified dynamically
5719 by the package's installation scripts).</p>
5722 However, programs that require dotfiles in order to
5723 operate sensibly (dotfiles that they do not create
5724 themselves automatically, that is) are a bad thing, and
5725 programs should be configured by the Debian default
5726 installation as close to normal as possible.</p>
5729 Therefore, if a program in a Debian package needs to be
5730 configured in some way in order to operate sensibly that
5731 configuration should be done in a site-wide global
5732 configuration file elsewhere in <tt>/etc</tt>. Only if the
5733 program doesn't support a site-wide default configuration
5734 and the package maintainer doesn't have time to add it
5735 may a default per-user file be placed in
5736 <tt>/etc/skel</tt>.</p>
5739 <tt>/etc/skel</tt> should be as empty as we can make it.
5740 This is particularly true because there is no easy
5741 mechanism for ensuring that the appropriate dotfiles are
5742 copied into the accounts of existing users when a package
5748 <heading>Log files</heading>
5750 The traditional approach to log files has been to set up ad
5751 hoc log rotation schemes using simple shell scripts and
5752 cron. While this approach is highly customizable, it
5753 requires quite a lot of sysadmin work. Even though the
5754 original Debian system helped a little by automatically
5755 installing a system which can be used as a template, this
5756 was deemed not enough.
5760 A better scheme is to use logrotate, a GPL'd program
5761 developed by Red Hat, which centralizes log management. It
5762 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5763 and a directory where packages can drop logrotation info
5764 (<tt>/etc/logrotate.d</tt>).
5768 Log files should usually be named
5769 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5770 log files, or need a separate directory for permissions
5771 reasons (<tt>/var/log</tt> is writable only by
5772 <tt>root</tt>), you should usually create a directory named
5773 <tt>/var/log/<var>package</var></tt>.</p>
5776 Log files must be rotated occasionally so
5777 that they don't grow indefinitely; the best way to do this
5778 is to drop a script into the directory
5779 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5780 logrotate. Here is a good example for a logrotate config
5781 file (for more information see <manref name="logrotate"
5789 /etc/init.d/foo force-reload
5793 Which rotates all files under `/var/log/foo', saves 12
5794 compressed generations, and sends a HUP signal at the end of
5800 Log files should be removed when the package is
5801 purged (but not when it is only removed), by checking the
5802 argument to the <tt>postrm</tt> script (see the <em>Debian
5803 Packaging Manual</em> for details).</p>
5808 <heading>Permissions and owners</heading>
5811 The rules in this section are guidelines for general use.
5812 If necessary you may deviate from the details below.
5813 However, if you do so you must make sure that what is done
5814 is secure and you should try to be as consistent as possible
5815 with the rest of the system. You should probably also
5816 discuss it on <prgn>debian-devel</prgn> first.</p>
5819 Files should be owned by <tt>root.root</tt>, and made
5820 writable only by the owner and universally readable (and
5821 executable, if appropriate).</p>
5824 Directories should be mode 755 or (for group-writability)
5825 mode 2775. The ownership of the directory should be
5826 consistent with its mode--if a directory is mode 2775, it
5827 should be owned by the group that needs write access to
5831 Setuid and setgid executables should be mode 4755 or 2755
5832 respectively, and owned by the appropriate user or group.
5833 They should not be made unreadable (modes like 4711 or
5834 2711 or even 4111); doing so achieves no extra security,
5835 because anyone can find the binary in the freely available
5836 Debian package--it is merely inconvenient. For the same
5837 reason you should not restrict read or execute permissions
5838 on non-set-id executables.</p>
5841 Some setuid programs need to be restricted to particular
5842 sets of users, using file permissions. In this case they
5843 should be owned by the uid to which they are set-id, and
5844 by the group which should be allowed to execute them.
5845 They should have mode 4754; there is no point in making
5846 them unreadable to those users who must not be allowed to
5850 You must not arrange that the system administrator can only
5851 reconfigure the package to correspond to their local
5852 security policy by changing the permissions on a binary.
5853 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5854 to conffiles and other similar objects) have their
5855 permissions reset to the distributed permissions when the
5856 package is reinstalled. Instead you should consider (for
5857 example) creating a group for people allowed to use the
5858 program(s) and making any setuid executables executable
5859 only by that group.</p>
5862 If you need to create a new user or group for your package
5863 there are two possibilities. Firstly, you may need to
5864 make some files in the binary package be owned by this
5865 user or group, or you may need to compile the user or
5866 group id (rather than just the name) into the binary
5867 (though this latter should be avoided if possible, as in
5868 this case you need a statically allocated id).</p>
5871 If you need a statically allocated id, you must ask for a
5872 user or group id from the base system
5873 maintainer, and must not release the package until you
5874 have been allocated one. Once you have been allocated one
5875 you must make the package depend on a version of the base
5876 system with the id present in <tt>/etc/passwd</tt> or
5877 <tt>/etc/group</tt>, or alternatively arrange for your
5878 package to create the user or group itself with the
5879 correct id (using <tt>adduser</tt>) in its pre- or
5880 post-installation script (the latter is to be preferred if
5881 it is possible).</p>
5884 On the other hand, the program might be able to determine the
5885 uid or gid from the group name at runtime, so that a
5886 dynamic id can be used. In this case you should choose an
5887 appropriate user or group name, discussing this on
5888 <prgn>debian-devel</prgn> and checking with the base
5889 system maintainer that it is unique and that they do not
5890 wish you to use a statically allocated id instead. When
5891 this has been checked you must arrange for your package to
5892 create the user or group if necessary using
5893 <prgn>adduser</prgn> in the pre- or post-installation
5894 script (again, the latter is to be preferred if it is
5898 Note that changing the numeric value of an id associated with a name
5899 is very difficult, and involves searching the file system for all
5900 appropriate files. You need to think carefully whether a static or
5901 dynamic id is required, since changing your mind later will cause
5906 <chapt id="customized-programs">
5907 <heading>Customized programs</heading>
5909 <sect id="arch-spec">
5910 <heading>Architecture specification strings</heading>
5913 If a program needs to specify an <em>architecture specification
5914 string</em> in some place, the following format should be used:
5916 <arch>-<os>
5918 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5919 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5920 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5921 operating system.</p>
5923 Note, that we don't want to use `<arch>-debian-linux'
5924 to apply to the rule `architecture-vendor-os' since this
5925 would make our programs incompatible to other Linux
5926 distributions. Also note, that we don't use
5927 `<arch>-unknown-linux', since the `unknown' does not
5928 look very good.</p></sect>
5932 <heading>Daemons</heading>
5935 The configuration files <tt>/etc/services</tt>,
5936 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5937 by the <prgn>netbase</prgn> package and may not be modified
5938 by other packages.</p>
5941 If a package requires a new entry in one of these files, the
5942 maintainer should get in contact with the
5943 <prgn>netbase</prgn> maintainer, who will add the entries
5944 and release a new version of the <prgn>netbase</prgn>
5948 The configuration file <tt>/etc/inetd.conf</tt> must not be
5949 modified by the package's scripts except via the
5950 <prgn>update-inetd</prgn> script or the
5951 <prgn>DebianNet.pm</prgn> Perl module.</p>
5954 If a package wants to install an example entry into
5955 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5956 exactly one hash character (<tt>#</tt>). Such lines are
5957 treated as `commented out by user' by the
5958 <prgn>update-inetd</prgn> script and are not changed or
5959 activated during a package updates.</p></sect>
5963 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5966 Some programs need to create pseudo-ttys. This should be done
5967 using Unix98 ptys if the C library supports it. The resulting
5968 program must not be installed setuid root, unless that
5969 is required for other functionality.
5973 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5974 <tt>/var/log/lastlog</tt> must be installed writeable by
5975 group utmp. Programs who need to modify those files must
5976 be installed setgid utmp.
5981 <heading>Editors and pagers</heading>
5984 Some programs have the ability to launch an editor or pager
5985 program to edit or display a text document. Since there are
5986 lots of different editors and pagers available in the Debian
5987 distribution, the system administrator and each user should
5988 have the possibility to choose his/her preferred editor and
5992 In addition, every program should choose a good default
5993 editor/pager if none is selected by the user or system
5997 Thus, every program that launches an editor or pager must
5998 use the EDITOR or PAGER environment variables to determine
5999 the editor/pager the user wants to get started. If these
6000 variables are not set, the programs <tt>/usr/bin/editor</tt>
6001 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
6004 These two files are managed through `alternatives.' That is,
6005 every package providing an editor or pager must call the
6006 <prgn>update-alternatives</prgn> script to register these
6010 If it is very hard to adapt a program to make us of the
6011 EDITOR and PAGER variables, that program may be configured
6012 to use <tt>/usr/bin/sensible-editor</tt> and
6013 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
6014 respectively. These are two scripts provided in the Debian
6015 base system that check the EDITOR and PAGER variables and
6016 launch the appropriate program or fall back to
6017 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
6021 A program may also use the VISUAL environment variable to
6022 determine the user's choice of editor. If it exists, it
6023 should take precedence over EDITOR. This is in fact what
6024 <tt>/usr/bin/sensible-editor</tt> does.</p>
6027 It is not required for a package to depend on
6028 `editor' and `pager', nor is it required for a package to
6029 provide such virtual packages.
6032 The Debian base system already provides an editor and
6041 <sect id="web-appl">
6042 <heading>Web servers and applications</heading>
6045 This section describes the locations and URLs that should
6046 be used by all web servers and web application in the Debian
6052 <p>Cgi-bin executable files are installed in the
6055 /usr/lib/cgi-bin/<cgi-bin-name>
6057 and should be referred to as
6059 http://localhost/cgi-bin/<cgi-bin-name>
6060 </example></p></item>
6063 <item><p>Access to html documents</p>
6066 Html documents for a package are stored in
6067 <tt>/usr/share/doc/<var>package</var></tt> but should
6068 be accessed via symlinks as
6069 <tt>/usr/doc/<var>package</var></tt><footnote> for
6070 backward compatibility, see <ref id="usrdoc"></footnote>
6071 and can be referred to as
6073 http://localhost/doc/<package>/<filename>
6074 </example></p></item>
6077 <item><p>Web Document Root</p>
6080 Web Applications should try to avoid storing files in
6081 the Web Document Root. Instead they should use the
6082 /usr/share/doc/<package> directory for documents and
6083 register the Web Application via the menu package. If
6084 access to the web-root is unavoidable then use
6088 as the Document Root. This might be just a
6089 symbolic link to the location where the sysadmin has
6090 put the real document root.</p>
6093 </enumlist></p></sect>
6096 <sect id="mail-transport-agents">
6097 <heading>Mail transport, delivery and user agents</heading>
6100 Debian packages which process electronic mail, whether
6101 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6102 must make sure that they are compatible with the
6103 configuration decisions below. Failure to do this may
6104 result in lost mail, broken <tt>From:</tt> lines, and other
6105 serious brain damage!</p>
6108 The mail spool is <tt>/var/mail</tt> and the interface
6109 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6110 per the FHS). On older systems, the mail spool may be
6111 physically located in /var/spool/mail, but all access to the
6112 mail spool should be via the /var/mail symlink. The mail
6113 spool is part of the base system and not part of the MTA
6118 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6119 programs (like IMAP daemons) must lock the mailbox in an
6120 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6121 be combined with dot locking. To avoid deadlocks, a
6122 program should use <tt>fcntl()</tt> first and dot locking
6123 after this or alternatively implement the two locking
6124 methods in a non blocking way<footnote>
6126 If it is not possible to establish both locks, the
6127 system shouldn't wait for the second lock to be
6128 established, but remove the first lock, wait a (random)
6129 time, and start over locking again.</p>
6130 </footnote>. Using the functions <tt>maillock</tt> and
6131 <tt>mailunlock</tt> provided by the
6132 <tt>liblockfile*</tt><footnote>
6134 <tt>liblockfile</tt> version >>1.01</p>
6135 </footnote> packages is the recommended way to realize this.
6139 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6140 unless the user has chosen otherwise. A MUA may remove a
6141 mailbox (unless it has nonstandard permissions) in which
6142 case the MTA or another MUA must recreate it if needed.
6143 Mailboxes must be writable by group mail.</p>
6146 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6147 be setgid mail to do the locking mentioned above (and
6148 must obviously avoid accessing other users' mailboxes
6149 using this privilege).</p>
6152 <tt>/etc/aliases</tt> is the source file for the system mail
6153 aliases (e.g., postmaster, usenet, etc.)--it is the one
6154 which the sysadmin and <tt>postinst</tt> scripts may edit.
6155 After <tt>/etc/aliases</tt> is edited the program or human
6156 editing it must call <prgn>newaliases</prgn>. All MTA
6157 packages must come with a <prgn>newaliases</prgn> program,
6158 even if it does nothing, but older MTA packages do not do
6159 this so programs should not fail if <prgn>newaliases</prgn>
6160 cannot be found.</p>
6163 The convention of writing <tt>forward to
6164 <var>address</var></tt> in the mailbox itself is not
6165 supported. Use a <tt>.forward</tt> file instead.</p>
6168 The <prgn>rmail</prgn> program used by UUCP
6169 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6170 Likewise, <prgn>rsmtp</prgn>, for receiving
6171 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6175 If you need to know what name to use (for example) on
6176 outgoing news and mail messages which are generated locally,
6177 you should use the file <tt>/etc/mailname</tt>. It will
6178 contain the portion after the username and <tt>@</tt> (at)
6179 sign for email addresses of users on the machine (followed
6183 A package should check for the existence of this file. If
6184 it exists it should use it without comment. (An MTA's
6185 prompting configuration script may wish to prompt the user
6186 even if it finds this file exists.) If it does not exist it
6187 should prompt the user for the value and store it in
6188 <tt>/etc/mailname</tt> as well as using it in the package's
6189 configuration. The prompt should make it clear that the
6190 name will not just be used by that package. For example, in
6191 this situation the INN package says:
6193 Please enter the `mail name' of your system. This is the
6194 hostname portion of the address to be shown on outgoing
6195 news and mail messages. The default is
6196 <var>syshostname</var>, your system's host name. Mail
6197 name [`<var>syshostname</var>']:
6199 where <var>syshostname</var> is the output of <tt>hostname
6200 --fqdn</tt>.</p></sect>
6204 <heading>News system configuration</heading>
6207 All the configuration files related to the NNTP (news)
6208 servers and clients should be located under
6209 <tt>/etc/news</tt>.</p>
6212 There are some configuration issues that apply to a number
6213 of news clients and server packages on the machine. These
6217 <tag>/etc/news/organization</tag>
6218 <item><p>A string which should appear as the
6219 organization header for all messages posted
6220 by NNTP clients on the machine</p></item>
6222 <tag>/etc/news/server</tag>
6223 <item><p>Contains the FQDN of the upstream NNTP
6224 server, or localhost if the local machine is
6225 an NNTP server.</p></item>
6228 Other global files may be added as required for cross-package news
6229 configuration.</p></sect>
6233 <heading>Programs for the X Window System</heading>
6236 <em>Programs that may be configured with support for the X Window
6237 System</em> must be configured to do so and must declare any
6238 package dependencies necessary to satisfy their runtime
6239 requirements when using the X Window System, unless the package
6240 in question is of standard or higher priority, in which case
6241 X-specific binaries may be split into a separate package, or
6242 alternative versions of the package with X support may be
6248 <em>Packages which provide an X server</em> that, directly or
6249 indirectly, communicates with real input and display hardware
6250 should declare in their control data that they provide the
6251 virtual package <tt>xserver</tt>.
6254 This implements current practice, and provides an actual
6255 policy for usage of the "xserver" virtual package which
6256 appears in the virtual packages list. In a nutshell, X
6257 servers that interface directly with the display and input
6258 hardware or via another subsystem (e.g., GGI) should provide
6259 xserver. Things like Xvfb, Xnest, and Xprt should not.
6265 <em>Packages that provide a terminal emulator</em> for the X
6266 Window System which support a terminal type with a terminfo
6267 description provided in the <tt>ncurses-base</tt> package
6268 should declare in their control data that they provide the
6269 virtual package <tt>x-terminal-emulator</tt>. They should
6270 also register themselves as an alternative for
6271 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6276 <em>Packages that provide window managers</em> should declare in
6277 their control data that they provide the virtual package
6278 <tt>x-window-manager</tt>. They should also register themselves as an
6279 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6280 calculated as follows:
6282 <item>Start with a priority of 20.</item>
6283 <item>If the window manager supports the Debian menu system,
6284 add 20 points if this support is available in the
6285 package's default configuration (i.e., no
6286 configuration files belonging to the system or user
6287 have to be edited to activate the feature); if
6288 configuration files must be modified, add only 10
6290 <item>If the window manager permits the X session to be
6291 restarted using a <em>different</em> window manager
6292 (without killing the X server) in its default
6293 configuration, add 10 points; otherwise add
6299 <em>Packages that provide fonts for the X Window System</em>
6300 must do a number of things to ensure that they are both
6301 available without modification of the X or font server
6302 configuration, and that they do not corrupt files used by
6303 other font packages to register information about themselves.
6306 Fonts of any type supported by the X Window System
6307 should be be in a separate binary package from any
6308 executables, libraries, or documentation (except that
6309 specific to the fonts shipped); if a program or
6310 library is <em>unusable</em> without one or more
6311 specific fonts, the package containing the program or
6312 library should declare a dependency on the package(s)
6313 containing the font(s) it requires.
6316 BDF fonts should be converted to PCF fonts with the
6317 <tt>bdftopcf</tt> utility (available in the
6318 <tt>xutils</tt> package), <tt>gzip</tt>ped, and
6319 placed in a directory that corresponds to their
6323 100 dpi fonts should be placed in
6324 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6327 75 dpi fonts should be placed in
6328 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6331 Character-cell fonts, cursor fonts, and other
6332 low-resolution fonts should be placed in
6333 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6338 Speedo fonts should be placed in
6339 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6342 Type 1 fonts should be placed in
6343 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6344 metric files are available, they may be placed here as
6348 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6349 other than those listed above should be neither created nor
6350 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6351 excepted for historical reasons, but installation of files into
6352 these directories remains discouraged.)
6355 Font packages may, instead of placing files directly in
6356 the X font directories listed above, provide symbolic links in
6357 the font directory which point to the files' actual location
6358 in the filesystem. Such a location should comply with the
6362 Font packages should not contain both 75dpi and 100dpi
6363 versions of a font. If both are available, they should be
6364 provided in separate binary packages with "-75dpi" or "-100dpi"
6365 appended to the names of the packages containing the
6366 corresponding fonts.
6369 Fonts destined for the <tt>misc</tt> subdirectory should
6370 not be included in the same package as 75dpi or 100dpi fonts;
6371 instead, they should be provided in a separate package with
6372 "-misc" appended to its name.
6375 Font packages <em>must not</em> provide the files
6376 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6377 <tt>fonts.scale</tt> in a font directory.
6380 <tt>fonts.dir</tt> files must not be provided at
6384 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6385 files, if needed, should be provided in the
6387 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6388 where <em>fontdir</em> is the name of the
6390 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6391 package's corresponding fonts are stored (e.g.,
6392 <tt>75dpi</tt> or <tt>misc</tt>),
6393 <em>package</em> is the name of the package that
6394 provides these fonts, and <em>extension</em> is
6395 either <tt>scale</tt> or <tt>alias</tt>,
6396 whichever corresponds to the file
6402 Font packages must declare a dependency on
6403 <tt>xutils</tt> and, in the package
6404 post-installation and post-removal scripts, invoke the
6405 <tt>mkfontdir</tt> command on each directory into
6406 which they installed fonts.
6409 Font packages that provide one or more
6410 <tt>fonts.scale</tt> files as described above must declare a
6411 versioned dependency on <tt>xutils (>=
6412 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6413 directory into which they installed fonts
6414 <em>before</em> invoking <tt>mkfontdir</tt> on that
6415 directory. This invocation must occur in both the
6416 post-installation and post-removal scripts.
6419 Font packages that provide one or more
6420 <tt>fonts.alias</tt> files as described above must
6421 declare a versioned dependency on <tt>xutils
6422 (>= 4.0.2)</tt> and, in the package
6423 post-installation and post-removal scripts, invoke
6424 <tt>update-fonts-alias</tt> on each directory into
6425 which they installed fonts.
6428 Font packages must not provide alias names for the
6429 fonts they include which collide with alias names already in
6430 use by fonts already packaged.
6433 Font packages must not provide fonts with the same XLFD
6434 registry name as another font already packaged.
6440 <em>Application defaults</em> files must be installed in the
6441 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6442 localized subdirectory of <tt>/etc/X11/</tt> as described in
6443 the <em>X Toolkit Intrinsics - C Language Interface</em>
6444 manual is also permitted). They must be registered as
6445 <em>conffile</em>s or handled as configuration files. For
6446 programs that are not linked against the X Toolkit (Xt)
6447 library, customization of programs' X resources may also be
6448 supported with the provision of a file with the same name as
6449 that of the package placed in the
6450 <tt>/etc/X11/Xresources/</tt> directory, which must
6451 registered as a <em>conffile</em> or handled as a
6452 configuration file. <em>Important:</em> packages that
6453 install files into the <tt>/etc/X11/Xresources/</tt>
6454 directory <em>must</em> declare a conflict with <tt>xbase
6455 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6456 possible for the installing package to destroy a
6457 previously-existing <tt>/etc/X11/Xresources</tt> file which
6458 had been customized by the system administrator.
6462 <em>Packages using the X Window System should abide by the FHS
6463 standard whenever possible</em>; they should install binaries,
6464 libraries, manual pages, and other files in FHS-mandated
6465 locations wherever possible. This means that files must
6466 not be installed into <tt>/usr/X11R6/bin/</tt>,
6467 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6468 this is necessary for the package to operate properly.
6469 Configuration files for window managers and display managers
6470 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6471 corresponding to the package name due to these programs'
6472 tight integration with the mechanisms of the X Window
6473 System. Application-level programs should use the
6474 <tt>/etc/</tt> directory unless otherwise mandated by
6475 policy. The installation of files into subdirectories of
6476 <tt>/usr/X11R6/include/X11/</tt> and
6477 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6478 package maintainers should determine if subdirectories of
6479 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6480 instead (symlinks from the X11R6 directories to
6481 FHS-compliant locations is encouraged if the program is not
6482 easily configured to look elsewhere for its files).
6483 Packages must not provide -- or install files into -- the
6484 directories <tt>/usr/bin/X11/</tt>,
6485 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6486 Files within a package should, however, make reference to
6487 these directories, rather than their X11R6-named
6488 counterparts <tt>/usr/X11R6/bin/</tt>,
6489 <tt>/usr/X11R6/include/X11/</tt>, and
6490 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6491 referred to have not been moved to FHS-compliant locations.
6495 <em>Programs that require the non-DFSG-compliant OSF/Motif
6496 library</em> should be compiled against and tested with
6497 LessTif (a free re-implementation of Motif) instead. If the
6498 maintainer judges that the program or programs do not work
6499 sufficiently well with LessTif to be distributed and
6500 supported, but do so when compiled against Motif, then two
6501 versions of the package should be created; one linked
6502 statically against Motif and with <tt>-smotif</tt> appended
6503 to the package name, and one linked dynamically against
6504 Motif and with <tt>-dmotif</tt> appended to the package
6505 name. Both Motif-linked versions are dependent upon
6506 non-DFSG-compliant software and thus cannot be uploaded to
6507 the main distribution; if the software is itself
6508 DFSG-compliant it may be uploaded to the contrib
6509 distribution. While known existing versions of OSF/Motif
6510 permit unlimited redistribution of binaries linked against
6511 the library (whether statically or dynamically), it is the
6512 package maintainer's responsibility to determine whether
6513 this is permitted by the license of the copy of OSF/Motif in
6514 his or her possession.
6519 <heading>Perl programs and modules</heading>
6521 Perl programs and modules should follow the current Perl
6522 policy as defined in the file found on
6523 <ftpsite>ftp.debian.org</ftpsite> in
6524 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
6525 or your local mirror. In addition, it is included in the
6526 <tt>debian-policy</tt> package.
6531 <heading>Emacs lisp programs</heading>
6534 Please refer to the `Debian Emacs Policy' (documented in
6535 <tt>debian-emacs-policy.gz</tt> of the
6536 <prgn>emacsen-common</prgn> package) for details of how to
6537 package emacs lisp programs.</p></sect>
6541 <heading>Games</heading>
6544 The permissions on /var/games are 755
6545 <tt>root.root</tt>.</p>
6548 Each game decides on its own security policy.</p>
6551 Games which require protected, privileged access to
6552 high-score files, savegames, etc., may be made
6553 set-<em>group</em>-id (mode 2755) and owned by
6554 <tt>root.games</tt>, and use files and directories with
6555 appropriate permissions (770 <tt>root.games</tt>, for
6556 example). They must not be made
6557 set-<em>user</em>-id, as this causes security problems. (If
6558 an attacker can subvert any set-user-id game they can
6559 overwrite the executable of any other, causing other players
6560 of these games to run a Trojan horse program. With a
6561 set-group-id game the attacker only gets access to less
6562 important game data, and if they can get at the other
6563 players' accounts at all it will take considerably more
6567 Some packages, for example some fortune cookie programs, are
6568 configured by the upstream authors to install with their
6569 data files or other static information made unreadable so
6570 that they can only be accessed through set-id programs
6571 provided. You should not do this in a Debian package: anyone can
6572 download the <tt>.deb</tt> file and read the data from it,
6573 so there is no point making the files unreadable. Not
6574 making the files unreadable also means that you don't have
6575 to make so many programs set-id, which reduces the risk of a
6579 As described in the FHS, binaries of games should be
6580 installed in the directory <tt>/usr/games</tt>. This also
6581 applies to games that use the X Window System. Manual pages
6582 for games (X and non-X games) should be installed in
6583 <tt>/usr/share/man/man6</tt>.</p>
6587 <chapt><heading>Documentation</heading>
6591 <heading>Manual pages</heading>
6594 You should install manual pages in <prgn>nroff</prgn> source
6595 form, in appropriate places under <tt>/usr/share/man</tt>. You
6596 should only use sections 1 to 9 (see the FHS for more
6597 details). You must not install a preformatted `cat
6601 Each program, utility, and function should have an
6602 associated manpage included in the same package. It is
6603 suggested that all configuration files also have a manual
6604 page included as well.
6608 If no manual page is available for a particular program,
6609 utility, function or configuration file and this is reported as a bug on
6610 debian-bugs, a symbolic link from the requested manual page
6611 to the <manref name="undocumented" section="7"> manual page
6612 may be provided. This symbolic link can be created from
6613 <tt>debian/rules</tt> like this:
6615 ln -s ../man7/undocumented.7.gz \
6616 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6618 This manpage claims that the lack of a manpage has been
6619 reported as a bug, so you may only do this if it really has
6620 (you can report it yourself, if you like). Do not close the
6621 bug report until a proper manpage is available.</p>
6624 You may forward a complaint about a missing manpage to the
6625 upstream authors, and mark the bug as forwarded in the
6626 Debian bug tracking system. Even though the GNU Project do
6627 not in general consider the lack of a manpage to be a bug,
6628 we do--if they tell you that they don't consider it a bug
6629 you should leave the bug in our bug tracking system open
6633 Manual pages should be installed compressed using <tt>gzip
6637 If one manpage needs to be accessible via several names it
6638 is better to use a symbolic link than the <tt>.so</tt>
6639 feature, but there is no need to fiddle with the relevant
6640 parts of the upstream source to change from <tt>.so</tt> to
6641 symlinks--don't do it unless it's easy. You should not create hard
6642 links in the manual page directories, nor put
6643 absolute filenames in <tt>.so</tt> directives. The filename
6644 in a <tt>.so</tt> in a manpage should be relative to the
6645 base of the manpage tree (usually
6646 <tt>/usr/share/man</tt>).</p></sect>
6650 <heading>Info documents</heading>
6653 Info documents should be installed in <tt>/usr/share/info</tt>.
6654 They should be compressed with <tt>gzip -9</tt>.</p>
6657 Your package should call <prgn>install-info</prgn> to update the Info
6659 file, in its post-installation script:
6661 install-info --quiet --section Development Development \
6662 /usr/share/info/foobar.info
6666 It is a good idea to specify a section for the location of
6667 your program; this is done with the <tt>--section</tt>
6668 switch. To determine which section to use, you should look
6669 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6670 relevant (or create a new section if none of the current
6671 sections are relevant). Note that the <tt>--section</tt>
6672 flag takes two arguments; the first is a regular expression
6673 to match (case-insensitively) against an existing section,
6674 the second is used when creating a new one.</p>
6677 You should remove the entries in the pre-removal script:
6679 install-info --quiet --remove /usr/share/info/foobar.info
6683 If <prgn>install-info</prgn> cannot find a description entry
6684 in the Info file you must supply one. See <manref
6685 name="install-info" section="8"> for details.</p>
6689 <heading>Additional documentation</heading>
6692 Any additional documentation that comes with the package may
6693 be installed at the discretion of the package maintainer.
6694 Text documentation should be installed in a directory
6695 <tt>/usr/share/doc/<var>package</var></tt>, where
6696 <var>package</var> is the name of the package, and
6697 compressed with <tt>gzip -9</tt> unless it is small.</p>
6700 If a package comes with large amounts of documentation which
6701 many users of the package will not require you should create
6702 a separate binary package to contain it, so that it does not
6703 take up disk space on the machines of users who do not need
6704 or want it installed.</p>
6707 It is often a good idea to put text information files
6708 (<tt>README</tt>s, changelogs, and so forth) that come with
6709 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6710 in the binary package. However, you don't need to install
6711 the instructions for building and installing the package, of
6715 Files in <tt>/usr/share/doc</tt> should not be referenced by
6716 any program, and the system administrator should be able to
6717 delete them without causing any programs to break. Any files
6718 that are referenced by programs but are also useful as
6719 standalone documentation should be installed under
6720 <tt>/usr/share/<package>/</tt> and symlinked in
6721 <tt>/usr/share/doc/<package>/</tt>.
6727 <heading>Accessing the documentation</heading>
6730 Former Debian releases placed all additional documentation
6731 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6733 <tt>/usr/share/doc/<var>package</var></tt>, each package
6734 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6735 that points to the new location of its documentation in
6736 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6737 symlinks will be removed in the future, but they have to be
6738 there for compatibility reasons until all packages have
6739 moved and the policy is changed accordingly.</footnote>.
6740 The symlink must be created when the package is installed;
6741 it cannot be contained in the package itself due to problems
6742 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6743 this is to put the following in the package's
6744 <prgn>postinst</prgn>:
6746 if [ "$1" = "configure" ]; then
6747 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6748 -a -d /usr/share/doc/#PACKAGE# ]; then
6749 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6753 And the following in the package's <prgn>prerm</prgn>:
6755 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6756 -a -L /usr/doc/#PACKAGE# ]; then
6757 rm -f /usr/doc/#PACKAGE#
6764 <heading>Preferred documentation formats</heading>
6767 The unification of Debian documentation is being carried out
6771 If your package comes with extensive documentation in a
6772 mark up format that can be converted to various other formats
6773 you should if possible ship HTML versions in a binary
6774 package, in the directory
6775 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6778 <p>The rationale: The important thing here is that HTML
6779 docs should be available in <em>some</em> package, not
6780 necessarily in the main binary package, though. </p>
6785 Other formats such as PostScript may be provided at your
6789 <sect id="copyrightfile">
6790 <heading>Copyright information</heading>
6793 Every package must be accompanied by a verbatim copy of its
6794 copyright and distribution license in the file
6795 /usr/share/doc/<package>/copyright. This file must
6796 neither be compressed nor be a symbolic link.</p>
6799 In addition, the copyright file must say where the upstream
6800 sources (if any) were obtained, and should explain briefly what
6801 modifications were made in the Debian version of the package
6802 compared to the upstream one. It should name the original
6803 authors of the package and the Debian maintainer(s) who were
6804 involved with its creation.</p>
6807 A copy of the file which will be installed in
6808 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6809 in <tt>debian/copyright</tt>.</p>
6813 /usr/share/doc/<package> may be a symbolic link to a
6814 directory in /usr/share/doc only if two packages both come from
6815 the same source and the first package has a "Depends"
6816 relationship on the second. These rules are important
6817 because copyrights must be extractable by mechanical
6821 Packages distributed under the UCB BSD license, the Artistic
6822 license, the GNU GPL, and the GNU LGPL should refer to the
6823 files /usr/share/common-licenses/BSD,
6824 /usr/share/common-licenses/Artistic,
6825 /usr/share/common-licenses/GPL, and
6826 /usr/share/common-licenses/LGPL.
6829 Why "licenses" and not "copyright"? Because
6830 <tt>/usr/doc/copyright</tt> used to contain all the
6831 copyright files, plus the four common licenses GPL,
6832 LGPL, Artistic and BSD. Now individual copyright files
6833 for packages are no longer in a common directory. Once
6834 <tt>/usr/doc/copyright</tt> is almost empty it makes
6835 sense to rename "copyright" to "licenses"
6838 Why "common-licenses" and not "licenses"? Because if I
6839 put just "licenses" I'm sure I will receive a bug report
6840 saying "license foo is not included in the licenses
6841 directory. They are not all the licenses, just a few
6842 common ones. I could use /usr/share/doc/common-licenses
6843 but I think this is too long, and, after all, the GPL
6844 does not "document" anything, it is merely a license.
6850 You should not use the copyright file as a general <tt>README</tt>
6851 file. If your package has such a file it should be
6852 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6853 <tt>README.Debian</tt> or some other appropriate place.</p>
6857 <heading>Examples</heading>
6860 Any examples (configurations, source files, whatever),
6861 should be installed in a directory
6862 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6863 files should not be referenced by any program--they're there
6864 for the benefit of the system administrator and users, as
6865 documentation only. Architecture-specific example files
6866 should be installed in a directory
6867 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6868 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6869 to files in it. Or the latter directory may be a symlink to
6873 <sect id="instchangelog">
6874 <heading>Changelog files</heading>
6877 Packages that are not Debian-native must contain a copy of
6878 <tt>debian/changelog</tt> file from the Debian source tree
6879 in <tt>/usr/share/doc/<var>package</var></tt> as
6880 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6881 available, it should be accessible as
6882 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6883 plain text. If the upstream changelog is distributed in
6884 HTML, it should be made available in that form as
6885 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6886 and the <tt>changelog.gz</tt> should be generated using, eg,
6887 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6888 do not already conform to this naming convention, then this
6889 may be achieved either by renaming the files, or adding a
6890 symbolic link, at the maintainer's discretion.
6893 Rationale: People should not have to look into two
6894 places for upstream changelogs merely because they are
6902 All these files should be installed compressed using <tt>gzip -9</tt>,
6903 as they will become large with time even if they start out
6908 If the package has only one changelog which is used both as
6909 the Debian changelog and the upstream one because there is
6910 no separate upstream maintainer then that changelog should
6911 usually be installed as
6912 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6913 there is a separate upstream maintainer, but no upstream
6914 changelog, then the Debian changelog should still be called
6915 <tt>changelog.Debian.gz</tt>.</p>