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8 Debian GNU/Linux Policy Manual.
9 Copyright (C)1996,1997,1998 Ian Jackson and Christian Schwarz;
10 released under the terms of the GNU
11 General Public License, version 2 or (at your option) any later.
12 Initial version 1996, Ian Jackson, ijackson@gnu.ai.mit.edu
13 Revised November 27, 1996, David A. Morris, bweaver@debian.org
14 New sections March 15, 1997, Christian Schwarz, schwarz@debian.org
15 Reworked/Restructured April-July 1997, Christian Schwarz, schwarz@debian.org
16 Maintainer since 1997, Christian Schwarz, schwarz@debian.org
17 Christoph Lameter contributed the "Web Standard"
18 The debian-policy mailing list has taken responsibility for the
19 contents of this document since September 1998, with the package
20 maintainers responsible for packaging administrivia only.
25 <title>Debian Policy Manual</title>
27 <name>Ian Jackson </name>
28 <email>ijackson@gnu.ai.mit.edu</email>
31 <name>Christian Schwarz</name>
32 <email>schwarz@debian.org</email>
35 <name>revised: David A. Morris</name>
36 <email>bweaver@debian.org</email>
39 <name>The Debian Policy mailing List</name>
40 <email>debian-policy@lists.debian.org</email>
42 <version>version &version;, &date;</version>
45 This manual describes the policy requirements for the Debian
46 GNU/Linux distribution. This includes the structure and
47 contents of the Debian archive and several design issues of the
48 operating system, as well as technical requirements that each
49 package must satisfy to be included in the distribution. The
50 policy package itself is maintained by a group of maintainers
51 that have no editorial powers. At the moment, the list of
55 <p>Julian Gilbey <email>jdg@debian.org</email></p>
58 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
66 Copyright ©1996,1997,1998 Ian Jackson
67 and Christian Schwarz.
70 This manual is free software; you may redistribute it and/or
71 modify it under the terms of the GNU General Public License
72 as published by the Free Software Foundation; either version
73 2, or (at your option) any later version.
77 This is distributed in the hope that it will be useful, but
78 <em>without any warranty</em>; without even the implied
79 warranty of merchantability or fitness for a particular
80 purpose. See the GNU General Public License for more
85 A copy of the GNU General Public License is available as
86 <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
87 distribution or on the World Wide Web at
88 <url id="http://www.gnu.org/copyleft/gpl.html"
89 name="The GNU General Public Licence">. You can also obtain it by writing to the
90 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
91 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 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 the 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/<ital><package-name></ital>/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 <ital>subsection</ital> if the package is in the
677 <em>main</em> section,
682 <ital>section/subsection</ital> 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
768 install 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>
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 in a common format, known as control files. Binary and
1462 source packages have control data as do the <tt>.changes</tt>
1463 files which control the installation of uploaded files, and
1464 <prgn>dpkg</prgn>'s internal databases are in a similar
1468 <sect><heading>Syntax of control files</heading>
1471 A file consists of one or more paragraphs of fields. The
1472 paragraphs are separated by blank lines. Some control files
1473 only allow one paragraph; others allow several, in which
1474 case each paragraph often refers to a different package.
1478 Each paragraph is a series of fields and values; each field
1479 consists of a name, followed by a colon and the value. It
1480 ends at the end of the line. Horizontal whitespace (spaces
1481 and tabs) may occur immediately before or after the value
1482 and is ignored there; it is conventional to put a single
1483 space after the colon.
1487 Some fields' values may span several lines; in this case
1488 each continuation line <em>must</em> start with a space or
1489 tab. Any trailing spaces or tabs at the end of individual
1490 lines of a field value are ignored.
1494 Except where otherwise stated only a single line of data is
1495 allowed and whitespace is not significant in a field body.
1496 Whitespace may never appear inside names (of packages,
1497 architectures, files or anything else), version numbers or
1498 in between the characters of multi-character version
1503 Field names are not case-sensitive, but it is usual to
1504 capitalize the field names using mixed case as shown below.
1508 Blank lines, or lines consisting only of spaces and tabs,
1509 are not allowed within field values or between fields - that
1510 would mean a new paragraph.
1514 It is important to note that there are several fields which
1515 are optional as far as <prgn>dpkg</prgn> and the related
1516 tools are concerned, but which must appear in every Debian
1517 package, or whose omission may cause problems. When writing
1518 the control files for Debian packages you <em>must</em> read
1519 the Debian policy manual in conjunction with the details
1520 below and the list of fields for the particular file.</p>
1523 <sect><heading>List of fields</heading>
1525 This list here is not supposed to be exhaustive. Most fields
1526 are dealt with elsewhere in this document and in the
1529 <sect1 id="f-Package"><heading><tt>Package</tt>
1533 The name of the binary package. Package names consist of
1534 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1535 (plus, minus and full stop).
1539 They must be at least two characters long and must start
1540 with an alphanumeric character. The use of lowercase
1541 package names is strongly recommended unless the package
1542 you're building (or referring to, in other fields) is
1543 already using uppercase.</p>
1546 <sect1 id="f-Version"><heading><tt>Version</tt>
1550 This lists the source or binary package's version number -
1551 see <ref id="versions">.
1557 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1561 The most recent version of the standards (the policy
1562 manual and associated texts) with which the package
1563 complies. This is updated manually when editing the
1564 source package to conform to newer standards; it can
1565 sometimes be used to tell when a package needs attention.
1569 Its format is the same as that of a version number except
1570 that no epoch or Debian revision is allowed - see <ref
1575 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1579 In a <tt>.changes</tt> file or parsed changelog output
1580 this contains the (space-separated) name(s) of the
1581 distribution(s) where this version of the package should
1582 be or was installed. Distribution names follow the rules
1583 for package names. (See <ref id="f-Package">).
1588 Current distribution values are:
1590 <tag><em>stable</em></tag>
1593 This is the current `released' version of Debian
1595 distribution is <em>stable</em> only major bug fixes
1596 are allowed. When changes are made to this
1597 distribution, the release number is increased
1598 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
1602 <tag><em>unstable</em></tag>
1605 This distribution value refers to the
1606 <em>developmental</em> part of the Debian
1607 distribution tree. New packages, new upstream
1608 versions of packages and bug fixes go into the
1609 <em>unstable</em> directory tree. Download from
1610 this distribution at your own risk.
1614 <tag><em>frozen</em></tag>
1617 From time to time, the <em>unstable</em>
1618 distribution enters a state of `code-freeze' in
1619 anticipation of release as a <em>stable</em>
1620 version. During this period of testing only
1621 fixes for existing or newly-discovered bugs will
1626 <tag><em>experimental</em></tag>
1629 The packages with this distribution value are deemed
1630 by their maintainers to be high risk. Oftentimes they
1631 represent early beta or developmental packages from
1632 various sources that the maintainers want people to
1633 try, but are not ready to be a part of the other parts
1634 of the Debian distribution tree. Download at your own
1639 There are several sections in each
1640 distribution. Currently, these sections are:
1643 <tag><em>main</em></tag>
1646 The packages in this section are those in the
1647 main Debian distribution. They are all free
1648 (according to the Debian free software
1649 guidelines) and meet any other criteria for
1650 inclusion described in this manual.</p>
1653 <tag><em>contrib</em></tag>
1656 The packages in this section do not meet the
1657 criteria for inclusion in the main Debian
1658 distribution as defined by this manual, but are
1659 otherwise free, as defined by the Debian free
1660 software guidelines.</p>
1663 <tag><em>non-free</em></tag>
1666 Packages in <em>non-free</em> do not meet the
1667 criteria of free software, as defined by the
1668 Debian free software guidelines. Again, use your
1669 best judgment in downloading from this
1673 </taglist> You should list <em>all</em> distributions that
1674 the package should be installed into. Except in unusual
1675 circumstances, installations to <em>stable</em> should also
1676 go into <em>frozen</em> (if it exists) and
1677 <em>unstable</em>. Likewise, installations into
1678 <em>frozen</em> should also go into <em>unstable</em>.
1687 <chapt id="versions"><heading>Version numbering </heading>
1690 Every package has a version number, in its <tt>Version</tt>
1695 The package management system imposes an ordering on version
1696 numbers, so that it can tell whether packages are being up- or
1697 downgraded and so that package system front end applications
1698 can tell whether a package it finds available is newer than
1699 the one installed on the system. The version number format
1700 has the most significant parts (as far as comparison is
1701 concerned) at the beginning.
1705 The version number format is:
1706 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream-version</var>[<tt>-</tt><var>debian-revision</var>]
1710 The three components here are:
1712 <tag><var>epoch</var></tag>
1716 This is a single (generally small) unsigned integer. It
1717 may be omitted, in which case zero is assumed. If it is
1718 omitted then the <var>upstream-version</var> may not
1723 It is provided to allow mistakes in the version numbers
1724 of older versions of a package, and also a package's
1725 previous version numbering schemes, to be left behind.
1730 <tag><var>upstream-version</var></tag>
1734 This is the main part of the version. It is usually the
1735 version number of the original (`upstream') package from
1736 which the <tt>.deb</tt> file has been made, if this is
1737 applicable. Usually this will be in the same format as
1738 that specified by the upstream author(s); however, it
1739 may need to be reformatted to fit into the package
1740 management system's format and comparison scheme.
1744 The comparison behavior of the package management system
1745 with respect to the <var>upstream-version</var> is
1746 described below. The <var>upstream-version</var>
1747 portion of the version number is mandatory.
1751 The <var>upstream-version</var> may contain only
1752 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
1753 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
1754 and should start with a digit. If there is no
1755 <var>debian-revision</var> then hyphens are not allowed;
1756 if there is no <var>epoch</var> then colons are not
1760 <tag><var>debian-revision</var></tag>
1764 This part of the version represents the version of the
1765 modifications that were made to the package to make it a
1766 Debian binary package. It is in the same format as the
1767 <var>upstream-version</var> and is compared in the same
1772 It is optional; if it isn't present then the
1773 <var>upstream-version</var> may not contain a hyphen.
1774 This format represents the case where a piece of
1775 software was written specifically to be turned into a
1776 Debian binary package, and so there is only one
1777 `debianization' of it and therefore no revision
1778 indication is required.
1782 It is conventional to restart the
1783 <var>debian-revision</var> at <tt>1</tt> each time the
1784 <var>upstream-version</var> is increased.
1788 The package management system will break the
1789 <var>upstream-version</var> and
1790 <var>debian-revision</var> apart at the last hyphen in
1791 the string. The absence of a <var>debian-revision</var>
1792 compares earlier than the presence of one (but note that
1793 the <var>debian-revision</var> is the least significant
1794 part of the version number).
1798 The <var>debian-revision</var> may contain only
1799 alphanumerics and the characters <tt>+</tt> and
1800 <tt>.</tt> (plus and full stop).
1804 The <var>upstream-version</var> and <var>debian-revision</var>
1805 parts are compared by the package management system using the
1810 The strings are compared from left to right.
1814 First the initial part of each string consisting entirely of
1815 non-digit characters is determined. These two parts (one of
1816 which may be empty) are compared lexically. If a difference
1817 is found it is returned. The lexical comparison is a
1818 comparison of ASCII values modified so that all the letters
1819 sort earlier than all the non-letters.
1823 Then the initial part of the remainder of each string which
1824 consists entirely of digit characters is determined. The
1825 numerical values of these two parts are compared, and any
1826 difference found is returned as the result of the comparison.
1827 For these purposes an empty string (which can only occur at
1828 the end of one or both version strings being compared) counts
1833 These two steps are repeated (chopping initial non-digit
1834 strings and initial digit strings off from the start) until a
1835 difference is found or both strings are exhausted.
1839 Note that the purpose of epochs is to allow us to leave behind
1840 mistakes in version numbering, and to cope with situations
1841 where the version numbering changes. It is <em>not</em> there
1842 to cope with version numbers containing strings of letters
1843 which the package management system cannot interpret (such as
1844 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
1845 author of this manual has heard of a package whose versions
1846 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
1847 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
1851 If an upstream package has problematic version numbers they
1852 should be converted to a sane form for use in the
1853 <tt>Version</tt> field.
1857 <heading>Version numbers based on dates</heading>
1859 In general, Debian packages should use the same version
1860 numbers as the upstream sources.</p>
1863 However, in some cases where the upstream version number is
1864 based on a date (e.g., a development `snapshot' release) the
1865 package management system cannot handle these version
1866 numbers without epochs. For example, dpkg will consider
1867 `96May01' to be greater than `96Dec24'.</p>
1870 To prevent having to use epochs for every new upstream
1871 version, the version number should be changed to the
1872 following format in such cases: `19960501', `19961224'. It
1873 is up to the maintainer whether he/she wants to bother the
1874 upstream maintainer to change the version numbers upstream,
1878 Note, that other version formats based on dates which are
1879 parsed correctly by the package management system should
1880 <em>not</em> be changed.</p>
1883 Native Debian packages (i.e., packages which have been
1884 written especially for Debian) whose version numbers include
1885 dates should always use the `YYYYMMDD' format.</p>
1889 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1891 <sect id="timestamps"><heading>Time Stamps</heading>
1893 Maintainers are encouraged to preserve the modification
1894 times of the upstream source files in a package, as far as
1895 is reasonably possible. Even though this is optional, this
1896 is still a good idea.
1899 The rationale is that there is some information conveyed
1900 by knowing the age of the file, for example, you could
1901 recognize that some documentation is very old by looking
1902 at the modification time, so it would be nice if the
1903 modification time of the upstream source would be
1910 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1911 main building script </heading>
1914 This file must be an executable makefile, and contains the
1915 package-specific recipes for compiling the package and
1916 building binary package(s) out of the source.
1920 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1921 so that it can be invoked by saying its name rather than
1922 invoking <prgn>make</prgn> explicitly.
1926 Since an interactive <tt>debian/rules</tt> script makes it
1927 impossible to auto-compile that package and also makes it
1928 hard for other people to reproduce the same binary
1929 package, all <strong>required targets</strong> MUST be
1930 non-interactive. At a minimum, required targets are the
1931 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1932 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1933 <em>binary-indep</em>, and <em>build</em>. It also follows
1934 that any target that these targets depend on must also be
1939 The targets which must be present are:
1941 <tag><tt>build</tt></tag>
1944 This should perform all non-interactive
1945 configuration and compilation of the package. If a
1946 package has an interactive pre-build configuration
1947 routine, the Debianised source package should be
1948 built after this has taken place, so that it can be
1949 built without rerunning the configuration.
1953 For some packages, notably ones where the same
1954 source tree is compiled in different ways to produce
1955 two binary packages, the <prgn>build</prgn> target
1956 does not make much sense. For these packages it is
1957 good enough to provide two (or more) targets
1958 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1959 for each of the ways of building the package, and a
1960 <prgn>build</prgn> target that does nothing. The
1961 <prgn>binary</prgn> target will have to build the
1962 package in each of the possible ways and make the
1963 binary package out of each.
1967 The <prgn>build</prgn> target must not do anything
1968 that might require root privilege.
1972 The <prgn>build</prgn> target may need to run
1973 <prgn>clean</prgn> first - see below.
1977 When a package has a configuration routine that
1978 takes a long time, or when the makefiles are poorly
1979 designed, or when <prgn>build</prgn> needs to run
1980 <prgn>clean</prgn> first, it is a good idea to
1981 <tt>touch build</tt> when the build process is
1982 complete. This will ensure that if <tt>debian/rules
1983 build</tt> is run again it will not rebuild the
1988 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1989 <tt>binary-indep</tt>
1993 The <prgn>binary</prgn> target must be all that is
1994 necessary for the user to build the binary
1995 package. All these targets are required to be
1996 non-interactive. It is split into two parts:
1997 <prgn>binary-arch</prgn> builds the packages' output
1998 files which are specific to a particular
1999 architecture, and <prgn>binary-indep</prgn> builds
2000 those which are not.
2004 <prgn>binary</prgn> may be (and commonly is) a target
2005 with no commands which simply depends on
2006 <prgn>binary-arch</prgn> and
2007 <prgn>binary-indep</prgn>.
2011 Both <prgn>binary-*</prgn> targets should depend on
2012 the <prgn>build</prgn> target, above, so that the
2013 package is built if it has not been already. It
2014 should then create the relevant binary package(s),
2015 using <prgn>dpkg-gencontrol</prgn> to make their
2016 control files and <prgn>dpkg-deb</prgn> to build
2017 them and place them in the parent of the top level
2022 If one of the <prgn>binary-*</prgn> targets has
2023 nothing to do (this will be always be the case if
2024 the source generates only a single binary package,
2025 whether architecture-dependent or not) it
2026 <em>must</em> still exist, and must always
2031 The <prgn>binary</prgn> targets must be invoked as
2036 <tag><tt>clean</tt></tag>
2040 This must undo any effects that the
2041 <prgn>build</prgn> and <prgn>binary</prgn> targets
2042 may have had, except that it should leave alone any
2043 output files created in the parent directory by a
2044 run of <prgn>binary</prgn>. This target must be
2049 If a <prgn>build</prgn> file is touched at the end
2050 of the <prgn>build</prgn> target, as suggested
2051 above, it should be removed as the first thing that
2052 <prgn>clean</prgn> does, so that running
2053 <prgn>build</prgn> again after an interrupted
2054 <prgn>clean</prgn> doesn't think that everything is
2059 The <prgn>clean</prgn> target may need to be
2060 invoked as root if <prgn>binary</prgn> has been
2061 invoked since the last <prgn>clean</prgn>, or if
2062 <prgn>build</prgn> has been invoked as root (since
2063 <prgn>build</prgn> may create directories, for
2068 <tag><tt>get-orig-source</tt> (optional)</tag>
2072 This target fetches the most recent version of the
2073 original source package from a canonical archive site
2074 (via FTP or WWW, for example), does any necessary
2075 rearrangement to turn it into the original source
2076 tar file format described below, and leaves it in the
2081 This target may be invoked in any directory, and
2082 should take care to clean up any temporary files it
2087 This target is optional, but providing it if
2088 possible is a good idea.
2094 The <prgn>build</prgn>, <prgn>binary</prgn> and
2095 <prgn>clean</prgn> targets must be invoked with a current
2096 directory of the package's top-level directory.
2101 Additional targets may exist in <tt>debian/rules</tt>,
2102 either as published or undocumented interfaces or for the
2103 package's internal use.
2107 The architecture we build on and build for is determined by
2108 make variables via dpkg-architecture. You can get the Debian
2109 architecture and the GNU style architecture specification
2110 string for the build machine as well as the host
2111 machine. Here is a list of supported make variables:
2112 <list compact="compact">
2114 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2117 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2118 specification string)</p>
2121 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
2124 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2130 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2131 the build machine or <tt>HOST</tt> for specification of the machine
2136 Backward compatibility can be provided in the rules file
2137 by setting the needed variables to suitable default
2138 values, please refer to the documentation of
2139 dpkg-architecture for details.
2143 It is important to understand that the <tt>DEB_*_ARCH</tt>
2144 string only determines which Debian architecture we are
2145 building on or for. It should not be used to get the CPU
2146 or system information; the GNU style variables should be
2151 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2155 This file records the changes to the Debian-specific parts of the
2159 Though there is nothing stopping an author who is also
2160 the Debian maintainer from using it for all their
2161 changes, it will have to be renamed if the Debian and
2162 upstream maintainers become different
2169 It has a special format which allows the package building
2170 tools to discover which version of the package is being
2171 built and find out other release-specific information.
2175 That format is a series of entries like this:
2177 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2179 * <var>change details</var>
2180 <var>more change details</var>
2181 * <var>even more change details</var>
2183 -- <var>maintainer name and email address</var> <var>date</var>
2188 <var>package</var> and <var>version</var> are the source
2189 package name and version number.
2193 <var>distribution(s)</var> lists the distributions where
2194 this version should be installed when it is uploaded - it
2195 is copied to the <tt>Distribution</tt> field in the
2196 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2200 <var>urgency</var> is the value for the <tt>Urgency</tt>
2201 field in the <tt>.changes</tt> file for the upload. It is
2202 not possible to specify an urgency containing commas; commas
2203 are used to separate
2204 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2205 <prgn>dpkg</prgn> changelog format (though there is
2206 currently only one useful <var>keyword</var>,
2211 The change details may in fact be any series of lines
2212 starting with at least two spaces, but conventionally each
2213 change starts with an asterisk and a separating space and
2214 continuation lines are indented so as to bring them in
2215 line with the start of the text above. Blank lines may be
2216 used here to separate groups of changes, if desired.
2220 The maintainer name and email address need <em>not</em>
2221 necessarily be those of the usual package maintainer.
2222 They should be the details of the person doing
2223 <em>this</em> version. The information here will be
2224 copied to the <tt>.changes</tt> file, and then later used
2225 to send an acknowledgement when the upload has been
2230 The <var>date</var> should be in RFC822 format
2233 This is generated by the <prgn>822-date</prgn>
2236 </footnote>; it should include the time zone specified
2237 numerically, with the time zone name or abbreviation
2238 optionally present as a comment.
2242 The first `title' line with the package name should start
2243 at the left hand margin; the `trailer' line with the
2244 maintainer and date details should be preceded by exactly
2245 one space. The maintainer details and the date must be
2246 separated by exactly two spaces.
2249 <sect1><heading>Defining alternative changelog formats</heading>
2252 It is possible to use a different format to the standard
2253 one, by providing a parser for the format you wish to
2257 A changelog parser must not interact with the user at
2263 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2264 and variable substitutions </heading>
2267 When <prgn>dpkg-gencontrol</prgn>,
2268 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2269 generate control files they do variable substitutions on
2270 their output just before writing it. Variable
2271 substitutions have the form
2272 <tt>${<var>variable-name</var>}</tt>. The optional file
2273 <tt>debian/substvars</tt> contains variable substitutions
2274 to be used; variables can also be set directly from
2275 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2276 source packaging commands, and certain predefined
2277 variables are available.
2281 The is usually generated and modified dynamically by
2282 <tt>debian/rules</tt> targets; in this case it must be
2283 removed by the <prgn>clean</prgn> target.
2287 See <manref name="dpkg-source" section="1"> for full
2288 details about source variable substitutions, including the
2289 format of <tt>debian/substvars</tt>.</p>
2292 <sect id="debianfiles"><heading><tt>debian/files</tt>
2296 This file is not a permanent part of the source tree; it
2297 is used while building packages to record which files are
2298 being generated. <prgn>dpkg-genchanges</prgn> uses it
2299 when it generates a <tt>.changes</tt> file.
2303 It should not exist in a shipped source package, and so it
2304 (and any backup files or temporary files such as
2308 <tt>files.new</tt> is used as a temporary file by
2309 <prgn>dpkg-gencontrol</prgn> and
2310 <prgn>dpkg-distaddfile</prgn> - they write a new
2311 version of <tt>files</tt> here before renaming it,
2312 to avoid leaving a corrupted copy if an error
2315 </footnote>) should be removed by the
2316 <prgn>clean</prgn> target. It may also be wise to
2317 ensure a fresh start by emptying or removing it at the
2318 start of the <prgn>binary</prgn> target.
2322 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2323 for the <tt>.deb</tt> file that will be created by
2324 <prgn>dpkg-deb</prgn> from the control file that it
2325 generates, so for most packages all that needs to be done
2326 with this file is to delete it in <prgn>clean</prgn>.
2330 If a package upload includes files besides the source
2331 package and any binary packages whose control files were
2332 made with <prgn>dpkg-gencontrol</prgn> then they should be
2333 placed in the parent of the package's top-level directory
2334 and <prgn>dpkg-distaddfile</prgn> should be called to add
2335 the file to the list in <tt>debian/files</tt>.</p>
2338 <sect id="restrictions"><heading>Restrictions on objects in source packages
2342 The source package may not contain any hard links
2345 This is not currently detected when building source
2346 packages, but only when extracting
2352 Hard links may be permitted at some point in the
2353 future, but would require a fair amount of
2356 </footnote>, device special files, sockets or setuid or
2360 Setgid directories are allowed.
2365 <sect id="descriptions"><heading>Descriptions of packages - the
2366 <tt>Description</tt> field </heading>
2369 The description is intended to describe the program to a user
2370 who has never met it before so that they know whether they
2371 want to install it. It should also give information about the
2372 significant dependencies and conflicts between this package
2373 and others, so that the user knows why these dependencies and
2374 conflicts have been declared.
2377 <sect1><heading>Notes about writing descriptions
2381 The single line synopsis should be kept brief - certainly
2382 under 80 characters.
2386 Do not include the package name in the synopsis line. The
2387 display software knows how to display this already, and you
2388 do not need to state it. Remember that in many situations
2389 the user may only see the synopsis line - make it as
2390 informative as you can.
2394 Do not try to continue the single line synopsis into the
2395 extended description. This will not work correctly when
2396 the full description is displayed, and makes no sense
2397 where only the summary (the single line synopsis) is
2402 The extended description should describe what the package
2403 does and how it relates to the rest of the system (in terms
2404 of, for example, which subsystem it is which part of).
2408 The description field needs to make sense to anyone, even
2409 people who have no idea about any of the things the
2413 The blurb that comes with a program in its
2414 announcements and/or <prgn>README</prgn> files is
2415 rarely suitable for use in a description. It is
2416 usually aimed at people who are already in the
2417 community where the package is used.
2423 Put important information first, both in the synopsis and
2424 extended description. Sometimes only the first part of the
2425 synopsis or of the description will be displayed. You can
2426 assume that there will usually be a way to see the whole
2427 extended description.
2431 You may include information about dependencies and so forth
2432 in the extended description, if you wish.
2436 Do not use tab characters. Their effect is not predictable.
2444 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2445 and installation procedure
2448 <sect><heading>Introduction to package maintainer scripts
2452 It is possible to supply scripts as part of a package which
2453 the package management system will run for you when your
2454 package is installed, upgraded or removed.
2458 These scripts should be the files <tt>preinst</tt>,
2459 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2460 control area of the package. They must be proper executable
2461 files; if they are scripts (which is recommended) they must
2462 start with the usual <tt>#!</tt> convention. They should be
2463 readable and executable by anyone, and not world-writable.
2467 The package management system looks at the exit status from
2468 these scripts. It is important that they exit with a
2469 non-zero status if there is an error, so that the package
2470 management system can stop its processing. For shell
2471 scripts this means that you <em>almost always</em> need to
2472 use <tt>set -e</tt> (this is usually true when writing shell
2473 scripts, in fact). It is also important, of course, that
2474 they don't exit with a non-zero status if everything went
2479 It is necessary for the error recovery procedures that the
2480 scripts be idempotent: i.e., invoking the same script several
2481 times in the same situation should do no harm. If the first
2482 call failed, or aborted half way through for some reason,
2483 the second call should merely do the things that were left
2484 undone the first time, if any, and exit with a success
2489 When a package is upgraded a combination of the scripts from
2490 the old and new packages is called in amongst the other
2491 steps of the upgrade procedure. If your scripts are going
2492 to be at all complicated you need to be aware of this, and
2493 may need to check the arguments to your scripts.
2497 Broadly speaking the <prgn>preinst</prgn> is called before
2498 (a particular version of) a package is installed, and the
2499 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2500 before (a version of) a package is removed and the
2501 <prgn>postrm</prgn> afterwards.
2504 <p> Programs called from maintainer scripts should not
2505 normally have a path prepended to them. Before installation
2506 is started the package management system checks to see if
2507 the programs <prgn>ldconfig</prgn>,
2508 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2509 and <prgn>update-rc.d</prgn> can be found via the
2510 <tt>PATH</tt> environment variable. Those programs, and any
2511 other program that one would expect to on the <tt>PATH</tt>,
2512 should thus be invoked without an absolute
2513 pathname. Maintainer scripts should also not reset the
2514 <tt>PATH</tt>, though they might choose to modify it by pre-
2515 or appending package-specific directories. These
2516 considerations really apply to all shell scripts.</p>
2519 <heading>Maintainer scripts Idempotency</heading>
2522 It is very important to make maintainer scripts
2526 That means that if it runs successfully or fails
2527 and then you call it again it doesn't bomb out,
2528 but just ensures that everything is the way it
2531 </footnote> This is so that if an error occurs, the
2532 user interrupts <prgn>dpkg</prgn> or some other
2533 unforeseen circumstance happens you don't leave the
2534 user with a badly-broken package.
2538 <heading>Controlling terminal for maintainer scripts</heading>
2541 The maintainer scripts are guaranteed to run with a
2542 controlling terminal and can interact with the user.
2543 If they need to prompt for passwords, do full-screen
2544 interaction or something similar you should do these
2545 things to and from <tt>/dev/tty</tt>, since
2546 <prgn>dpkg</prgn> will at some point redirect scripts'
2547 standard input and output so that it can log the
2548 installation process. Likewise, because these scripts
2549 may be executed with standard output redirected into a
2550 pipe for logging purposes, Perl scripts should set
2551 unbuffered output by setting <tt>$|=1</tt> so that the
2552 output is printed immediately rather than being
2557 Each script should return a zero exit status for
2558 success, or a nonzero one for failure.
2562 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2567 <list compact="compact">
2569 <p><var>new-preinst</var> <tt>install</tt></p>
2572 <p><var>new-preinst</var> <tt>install</tt>
2573 <var>old-version</var></p>
2576 <p><var>new-preinst</var> <tt>upgrade</tt>
2577 <var>old-version</var></p>
2580 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2581 <var>new-version</var>
2587 <list compact="compact">
2589 <p><var>postinst</var> <tt>configure</tt>
2590 <var>most-recently-configured-version</var></p>
2593 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2594 <var>new version</var></p>
2597 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2598 <tt>in-favour</tt> <var>package</var>
2599 <var>new-version</var></p>
2603 <var>deconfigured's-postinst</var>
2604 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2605 <var>failed-install-package</var> <var>version</var>
2606 <tt>removing</tt> <var>conflicting-package</var>
2613 <list compact="compact">
2615 <p><var>prerm</var> <tt>remove</tt></p>
2618 <p><var>old-prerm</var> <tt>upgrade</tt>
2619 <var>new-version</var></p>
2622 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2623 <var>old-version</var></p>
2626 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2627 <tt>in-favour</tt> <var>package</var>
2628 <var>new-version</var></p>
2632 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2633 <tt>in-favour</tt> <var>package-being-installed</var>
2634 <var>version</var> <tt>removing</tt>
2635 <var>conflicting-package</var>
2642 <list compact="compact">
2644 <p><var>postrm</var> <tt>remove</tt></p>
2647 <p><var>postrm</var> <tt>purge</tt></p>
2651 <var>old-postrm</var> <tt>upgrade</tt>
2652 <var>new-version</var></p>
2655 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2656 <var>old-version</var></p>
2659 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2662 <p><var>new-postrm</var> <tt>abort-install</tt>
2663 <var>old-version</var></p>
2666 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2667 <var>old-version</var></p>
2671 <var>disappearer's-postrm</var> <tt>disappear</tt>
2672 <var>overwriter</var>
2673 <var>overwriter-version</var></p></item>
2678 <sect id="unpackphase"><heading>Details of unpack phase of
2679 installation or upgrade
2683 The procedure on installation/upgrade/overwrite/disappear
2684 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2685 stage of <tt>dpkg --install</tt>) is as follows. In each
2686 case if an error occurs the actions are, in general, run
2687 backwards - this means that the maintainer scripts are run
2688 with different arguments in reverse order. These are the
2689 `error unwind' calls listed below.
2696 <p>If a version of the package is already
2699 <var>old-prerm</var> upgrade <var>new-version</var>
2704 If the script runs but exits with a non-zero
2705 exit status, <prgn>dpkg</prgn> will attempt:
2707 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2709 Error unwind, for both the above cases:
2711 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2719 <p>If a `conflicting' package is being removed at the same time:
2723 If any packages depended on that conflicting
2724 package and <tt>--auto-deconfigure</tt> is
2725 specified, call, for each such package:
2727 <var>deconfigured's-prerm</var> deconfigure \
2728 in-favour <var>package-being-installed</var> <var>version</var> \
2729 removing <var>conflicting-package</var> <var>version</var>
2733 <var>deconfigured's-postinst</var> abort-deconfigure \
2734 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2735 removing <var>conflicting-package</var> <var>version</var>
2737 The deconfigured packages are marked as
2738 requiring configuration, so that if
2739 <tt>--install</tt> is used they will be
2740 configured again if possible.</p>
2743 <p>To prepare for removal of the conflicting package, call:
2745 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2749 <var>conflictor's-postinst</var> abort-remove \
2750 in-favour <var>package</var> <var>new-version</var>
2761 <p>If the package is being upgraded, call:
2763 <var>new-preinst</var> upgrade <var>old-version</var>
2768 Otherwise, if the package had some configuration
2769 files from a previous version installed (i.e., it
2770 is in the `configuration files only' state):
2772 <var>new-preinst</var> install <var>old-version</var>
2776 <p>Otherwise (i.e., the package was completely purged):
2778 <var>new-preinst</var> install
2780 Error unwind versions, respectively:
2782 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2783 <var>new-postrm</var> abort-install <var>old-version</var>
2784 <var>new-postrm</var> abort-install
2794 The new package's files are unpacked, overwriting any
2795 that may be on the system already, for example any
2796 from the old version of the same package or from
2797 another package (backups of the old files are left
2798 around, and if anything goes wrong the package
2799 management system will attempt to put them back as
2800 part of the error unwind).
2804 It is an error for a package to contains files which
2805 are on the system in another package, unless
2806 <tt>Replaces</tt> is used (see <ref id="replaces">).
2807 Currently the <tt>--force-overwrite</tt> flag is
2808 enabled, downgrading it to a warning, but this may not
2813 It is a more serious error for a package to contain a
2814 plain file or other kind of non-directory where another
2815 package has a directory (again, unless
2816 <tt>Replaces</tt> is used). This error can be
2817 overridden if desired using
2818 <tt>--force-overwrite-dir</tt>, but this is not
2823 Packages which overwrite each other's files produce
2824 behavior which though deterministic is hard for the
2825 system administrator to understand. It can easily
2826 lead to `missing' programs if, for example, a package
2827 is installed which overwrites a file from another
2828 package, and is then removed again.
2831 Part of the problem is due to what is arguably a
2832 bug in <prgn>dpkg</prgn>.
2838 A directory will never be replaced by a symbolic links
2839 to a directory or vice versa; instead, the existing
2840 state (symlink or not) will be left alone and
2841 <prgn>dpkg</prgn> will follow the symlink if there is
2849 <p>If the package is being upgraded, call
2851 <var>old-postrm</var> upgrade <var>new-version</var>
2855 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2857 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2859 Error unwind, for both cases:
2861 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2867 This is the point of no return - if
2868 <prgn>dpkg</prgn> gets this far, it won't back off
2869 past this point if an error occurs. This will
2870 leave the package in a fairly bad state, which
2871 will require a successful re-installation to clear
2872 up, but it's when <prgn>dpkg</prgn> starts doing
2873 things that are irreversible.
2878 Any files which were in the old version of the package
2879 but not in the new are removed.</p>
2882 <p>The new file list replaces the old.</p>
2885 <p>The new maintainer scripts replace the old.</p>
2889 <p>Any packages all of whose files have been overwritten during the
2890 installation, and which aren't required for
2891 dependencies, are considered to have been removed.
2892 For each such package,
2895 <p><prgn>dpkg</prgn> calls:
2897 <var>disappearer's-postrm</var> disappear \
2898 <var>overwriter</var> <var>overwriter-version</var>
2903 <p>The package's maintainer scripts are removed.
2908 It is noted in the status database as being in a
2909 sane state, namely not installed (any conffiles
2910 it may have are ignored, rather than being
2911 removed by <prgn>dpkg</prgn>). Note that
2912 disappearing packages do not have their prerm
2913 called, because <prgn>dpkg</prgn> doesn't know
2914 in advance that the package is going to
2923 Any files in the package we're unpacking that are also
2924 listed in the file lists of other packages are removed
2925 from those lists. (This will lobotomize the file list
2926 of the `conflicting' package if there is one.)
2931 The backup files made during installation, above, are
2938 The new package's status is now sane, and recorded as
2939 `unpacked'. Here is another point of no return - if
2940 the conflicting package's removal fails we do not
2941 unwind the rest of the installation; the conflicting
2942 package is left in a half-removed limbo.
2947 If there was a conflicting package we go and do the
2948 removal actions (described below), starting with the
2949 removal of the conflicting package's files (any that
2950 are also in the package being installed have already
2951 been removed from the conflicting package's file list,
2952 and so do not get removed now).
2959 <sect><heading>Details of configuration</heading>
2962 When we configure a package (this happens with <tt>dpkg
2963 --install</tt>, or with <tt>--configure</tt>), we first
2964 update the conffiles and then call:
2966 <var>postinst</var> configure <var>most-recently-configured-version</var>
2971 No attempt is made to unwind after errors during
2976 If there is no most recently configured version
2977 <prgn>dpkg</prgn> will pass a null argument; older versions
2978 of dpkg may pass <tt><unknown></tt> (including the
2979 angle brackets) in this case. Even older ones do not pass a
2980 second argument at all, under any circumstances.
2984 <sect><heading>Details of removal and/or configuration purging
2992 <var>prerm</var> remove
2998 The package's files are removed (except conffiles).
3003 <var>postrm</var> remove
3007 <p>All the maintainer scripts except the postrm are removed.
3011 If we aren't purging the package we stop here. Note
3012 that packages which have no postrm and no conffiles
3013 are automatically purged when removed, as there is no
3014 difference except for the <prgn>dpkg</prgn>
3019 The conffiles and any backup files (<tt>~</tt>-files,
3020 <tt>#*#</tt> files, <tt>%</tt>-files,
3021 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3025 <var>postrm</var> purge
3029 <p>The package's file list is removed.</p>
3032 No attempt is made to unwind after errors during
3038 <chapt id="relationships"><heading>Declaring relationships between
3042 Packages can declare in their control file that they have
3043 certain relationships to other packages - for example, that
3044 they may not be installed at the same time as certain other
3045 packages, and/or that they depend on the presence of others,
3046 or that they should overwrite files in certain other packages
3051 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3052 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3053 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3057 Source packages may declare relationships to binary packages,
3058 saying that they require certain binary packages to be
3059 installed or absent at the time of building the package.
3063 This is done using the <tt>Build-Depends</tt>,
3064 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3065 <tt>Build-Conflicts-Indep</tt> control file fields.
3068 <sect id="depsyntax"><heading>Syntax of relationship fields
3072 These fields all have a uniform syntax. They are a list of
3073 package names separated by commas.
3077 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3078 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3079 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3080 control file fields of the package, which declare
3081 dependencies on other packages, the package names listed may
3082 also include lists of alternative package names, separated
3083 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3084 a case, the presence of any one of the alternative packages
3085 is installed, that part of the dependency is considered to
3090 All the fields except <tt>Provides</tt> may restrict their
3091 applicability to particular versions of each named package.
3092 This is done in parentheses after each individual package
3093 name; the parentheses should contain a relation from the
3094 list below followed by a version number, in the format
3095 described in <ref id="versions">.
3099 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3100 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3101 strictly earlier, earlier or equal, exactly equal, later or
3102 equal and strictly later, respectively. The forms
3103 <tt><</tt> and <tt>></tt> were used to mean
3104 earlier/later or equal, rather than strictly earlier/later,
3105 so they should not appear in new packages (though
3106 <prgn>dpkg</prgn> still supports them).
3110 Whitespace may appear at any point in the version
3111 specification, and must appear where it's necessary to
3112 disambiguate; it is not otherwise significant. For
3113 consistency and in case of future changes to
3114 <prgn>dpkg</prgn> it is recommended that a single space be
3115 used after a version relationship and before a version
3116 number; it is usual also to put a single space after each
3117 comma, on either side of each vertical bar, and before each
3126 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3131 All fields that specify build-time relationships
3132 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3133 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3134 may be restricted to a certain set of architectures. This
3135 is done in brackets after each individual package name and
3136 the optional version specification. The brackets enclose a
3137 list of Debian architecture names separated by whitespace.
3138 Exclamation marks may be prepended to each of the names.
3139 (It is not permitted for some names to be prepended with
3140 exclamation marks and others not.) If the current Debian
3141 host architecture is not in this list and there are no
3142 exclamation marks in the list, or it is in the list with a
3143 prepended exclamation mark, the package name and the
3144 associated version specification are ignored completely for
3145 the purposes of defining the relationships.
3152 Build-Depends-Indep: texinfo
3153 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3154 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3160 <heading>Binary Dependencies - <tt>Depends</tt>,
3161 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3162 <tt>Pre-Depends</tt>
3166 These five fields are used to declare a dependency
3167 relationship by one package on another. They appear in the
3168 depending package's control file.
3172 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3173 (discussed below) take effect <em>only</em> when a package
3174 is to be configured. They do not prevent a package being on
3175 the system in an unconfigured state while its dependencies
3176 are unsatisfied, and it is possible to replace a package
3177 whose dependencies are satisfied and which is properly
3178 installed with a different version whose dependencies are
3179 not and cannot be satisfied; when this is done the depending
3180 package will be left unconfigured (since attempts to
3181 configure it will give errors) and will not function
3186 For this reason packages in an installation run are usually
3187 all unpacked first and all configured later; this gives
3188 later versions of packages with dependencies on later
3189 versions of other packages the opportunity to have their
3190 dependencies satisfied.
3194 Thus <tt>Depends</tt> allows package maintainers to impose
3195 an order in which packages should be configured.
3197 <tag><tt>Depends</tt></tag>
3200 <p>This declares an absolute dependency.
3204 The <tt>Depends</tt> field should be used if the
3205 depended-on package is required for the depending
3206 package to provide a significant amount of
3210 <tag><tt>Recommends</tt></tag>
3212 <p>This declares a strong, but not absolute, dependency.
3216 The <tt>Recommends</tt> field should list packages
3217 that would be found together with this one in all but
3218 unusual installations.</p>
3221 <tag><tt>Suggests</tt></tag>
3225 This is used to declare that one package may be more
3226 useful with one or more others. Using this field
3227 tells the packaging system and the user that the
3228 listed packages are related to this one and can
3229 perhaps enhance its usefulness, but that installing
3230 this one without them is perfectly reasonable.
3234 <tag><tt>Enhances</tt></tag>
3237 This field is similar to Suggests but works in the
3238 opposite direction. It is used to declare that a
3239 package can enhance the functionality of another
3244 <tag><tt>Pre-Depends</tt></tag>
3248 This field is like <tt>Depends</tt>, except that it
3249 also forces <prgn>dpkg</prgn> to complete installation
3250 of the packages named before even starting the
3251 installation of the package which declares the
3256 <tt>Pre-Depends</tt> should be used sparingly,
3257 preferably only by packages whose premature upgrade or
3258 installation would hamper the ability of the system to
3259 continue with any upgrade that might be in progress.
3263 When the package declaring it is being configured, a
3264 <tt>Pre-Dependency</tt> will be considered satisfied
3265 only if the depending package has been correctly
3266 configured, just as if an ordinary <tt>Depends</tt>
3271 However, when a package declaring a Pre-dependency is
3272 being unpacked the predependency can be satisfied even
3273 if the depended-on package(s) are only unpacked or
3274 half-configured, provided that they have been
3275 configured correctly at some point in the past (and
3276 not removed or partially removed since). In this case
3277 both the previously-configured and currently unpacked
3278 or half-configured versions must satisfy any version
3279 clause in the <tt>Pre-Depends</tt> field.
3285 When selecting which level of dependency to use you should
3286 consider how important the depended-on package is to the
3287 functionality of the one declaring the dependency. Some
3288 packages are composed of components of varying degrees of
3289 importance. Such a package should list using
3290 <tt>Depends</tt> the package(s) which are required by the
3291 more important components. The other components'
3292 requirements may be mentioned as Suggestions or
3293 Recommendations, as appropriate to the components' relative
3298 <sect id="conflicts"><heading>Alternative binary packages -
3299 <tt>Conflicts</tt> and <tt>Replaces</tt>
3303 When one binary package declares a conflict with another
3304 <prgn>dpkg</prgn> will refuse to allow them to be installed
3305 on the system at the same time.
3309 If one package is to be installed, the other must be removed
3310 first - if the package being installed is marked as
3311 replacing (<ref id="replaces">) the one on the system, or
3312 the one on the system is marked as deselected, or both
3313 packages are marked <tt>Essential</tt>, then
3314 <prgn>dpkg</prgn> will automatically remove the package
3315 which is causing the conflict, otherwise it will halt the
3316 installation of the new package with an error. This
3317 mechanism specifically doesn't work when the installed
3318 package is <tt>Essential</tt>, but the new package is not.
3323 A package will not cause a conflict merely because its
3324 configuration files are still installed; it must be at least
3329 A special exception is made for packages which declare a
3330 conflict with their own package name, or with a virtual
3331 package which they provide (see below): this does not
3332 prevent their installation, and allows a package to conflict
3333 with others providing a replacement for it. You use this
3334 feature when you want the package in question to be the only
3335 package providing something.
3339 A <tt>Conflicts</tt> entry should almost never have an
3340 `earlier than' version clause. This would prevent
3341 <prgn>dpkg</prgn> from upgrading or installing the package
3342 which declared such a conflict until the upgrade or removal
3343 of the conflicted-with package had been completed.
3347 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3351 As well as the names of actual (`concrete') packages, the
3352 package relationship fields <tt>Depends</tt>,
3353 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3354 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3355 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3356 mention virtual packages.
3360 A virtual package is one which appears in the
3361 <tt>Provides</tt> control file field of another package.
3362 The effect is as if the package(s) which provide a
3363 particular virtual package name had been listed by name
3364 everywhere the virtual package name appears.
3368 If there are both a real and a virtual package of the same
3369 name then the dependency may be satisfied (or the conflict
3370 caused) by either the real package or any of the virtual
3371 packages which provide it. This is so that, for example,
3377 and someone else releases an xemacs package they can say
3381 </example> and all will work in the interim (until a purely
3382 virtual package name is decided on and the <tt>emacs</tt>
3383 and <tt>vm</tt> packages are changed to use it).
3387 If a dependency or a conflict has a version number attached
3388 then only real packages will be considered to see whether
3389 the relationship is satisfied (or the prohibition violated,
3390 for a conflict) - it is assumed that a real package which
3391 provides the virtual package is not of the `right' version.
3392 So, a <tt>Provides</tt> field may not contain version
3393 numbers, and the version number of the concrete package
3394 which provides a particular virtual package will not be
3395 looked at when considering a dependency on or conflict with
3396 the virtual package name.
3400 It is likely that the ability will be added in a future
3401 release of <prgn>dpkg</prgn> to specify a version number for
3402 each virtual package it provides. This feature is not yet
3403 present, however, and is expected to be used only
3408 If you want to specify which of a set of real packages should be the
3409 default to satisfy a particular dependency on a virtual package, you
3410 should list the real package as an alternative before the virtual.
3415 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3416 files and replacing packages
3420 The <tt>Replaces</tt> control file field has two purposes,
3421 which come into play in different situations.
3425 Virtual packages (<ref id="virtual">) are not considered
3426 when looking at a <tt>Replaces</tt> field - the packages
3427 declared as being replaced must be mentioned by their real
3431 <sect1><heading>Overwriting files in other packages
3435 Firstly, as mentioned before, it is usually an error for a
3436 package to contain files which are on the system in
3437 another package, though currently the
3438 <tt>--force-overwrite</tt> flag is enabled by default,
3439 downgrading the error to a warning,
3443 If the overwriting package declares that it replaces the
3444 one containing the file being overwritten then
3445 <prgn>dpkg</prgn> will proceed, and replace the file from
3446 the old package with that from the new. The file will no
3447 longer be listed as `owned' by the old package.
3451 If a package is completely replaced in this way, so that
3452 <prgn>dpkg</prgn> does not know of any files it still
3453 contains, it is considered to have disappeared. It will
3454 be marked as not wanted on the system (selected for
3455 removal) and not installed. Any conffiles details noted
3456 in the package will be ignored, as they will have been
3457 taken over by the replacing package(s). The package's
3458 <prgn>postrm</prgn> script will be run to allow the
3459 package to do any final cleanup required. See <ref
3460 id="mscriptsinstact">.
3464 In the future <prgn>dpkg</prgn> will discard files which
3465 would overwrite those from an already installed package
3466 which declares that it replaces the package being
3467 installed. This is so that you can install an older
3468 version of a package without problems.
3472 This usage of <tt>Replaces</tt> only takes effect when
3473 both packages are at least partially on the system at
3474 once, so that it can only happen if they do not conflict
3475 or if the conflict has been overridden.</p>
3478 <sect1><heading>Replacing whole packages, forcing their
3483 Secondly, <tt>Replaces</tt> allows the packaging system to
3484 resolve which package should be removed when there is a
3485 conflict - see <ref id="conflicts">. This usage only
3486 takes effect when the two packages <em>do</em> conflict,
3487 so that the two effects do not interfere with each other.
3492 <sect><heading>Relationships between source and binary packages -
3493 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3494 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3498 A source package may declare a dependency or a conflict on a
3499 binary package. This is done with the control file fields
3500 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3501 <tt>Build-Conflicts</tt>, and
3502 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3503 the dependencies and conflicts they define must be satisfied
3504 (as defined earlier for binary packages), when one of the
3505 targets in <tt>debian/rules</tt> that the particular field
3506 applies to is invoked.
3509 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3512 The <tt>Build-Depends</tt> and
3513 <tt>Build-Conflicts</tt> fields apply to the targets
3514 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3515 and <tt>binary-indep</tt>.
3518 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3521 The <tt>Build-Depends-Indep</tt> and
3522 <tt>Build-Conflicts-Indep</tt> fields apply to the
3523 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3534 <chapt id="conffiles"><heading>Configuration file handling
3538 <prgn>dpkg</prgn> can do a certain amount of automatic
3539 handling of package configuration files.
3543 Whether this mechanism is appropriate depends on a number of
3544 factors, but basically there are two approaches to any
3545 particular configuration file.
3549 The easy method is to ship a best-effort configuration in the
3550 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3551 handle updates. If the user is unlikely to want to edit the
3552 file, but you need them to be able to without losing their
3553 changes, and a new package with a changed version of the file
3554 is only released infrequently, this is a good approach.
3558 The hard method is to build the configuration file from
3559 scratch in the <prgn>postinst</prgn> script, and to take the
3560 responsibility for fixing any mistakes made in earlier
3561 versions of the package automatically. This will be
3562 appropriate if the file is likely to need to be different on
3567 <chapt id="sharedlibs"><heading>Shared libraries
3571 Packages containing shared libraries must be constructed with
3572 a little care to make sure that the shared library is always
3573 available. This is especially important for packages whose
3574 shared libraries are vitally important, such as the libc.
3578 Firstly, your package should install the shared libraries
3579 under their normal names. For example, the
3580 <prgn>libgdbm1</prgn> package should install
3581 <tt>libgdbm.so.1.7.3</tt> as
3582 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3583 renamed or re-linked by any prerm or postrm scripts;
3584 <prgn>dpkg</prgn> will take care of renaming things safely
3585 without affecting running programs, and attempts to interfere
3586 with this are likely to lead to problems.
3590 Secondly, your package should include the symlink that
3591 <prgn>ldconfig</prgn> would create for the shared libraries.
3592 For example, the <prgn>libgdbm1</prgn> package should include
3593 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3594 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3595 <prgn>ld.so</prgn> can find the library in between the time
3596 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3597 in the <prgn>postinst</prgn> script. Furthermore, older
3598 versions of the package management system required the library
3599 must be placed before the symlink pointing to it in the
3600 <tt>.deb</tt> file. This is so that by the time
3601 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3602 the previous symlink pointing at an older version of the
3603 library) the new shared library is already in place.
3604 Unfortunately, this was not not always possible, since it
3605 highly depends on the behavior of the file system. Some
3606 file systems (such as reiserfs) will reorder the files so it
3607 doesn't matter in what order you create them. Starting with
3608 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3609 files itself when building a package.
3613 Thirdly, the development package should contain a symlink for
3614 the shared library without a version number. For example, the
3615 <tt>libgdbm1-dev</tt> package should include a symlink from
3616 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3617 symlink is needed by <prgn>ld</prgn> when compiling packages
3618 as it will only look for <tt>libgdm.so</tt> and
3619 <tt>libgdm.a</tt> when compiling dynamically or statically,
3624 Any package installing shared libraries in a directory that's listed
3625 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3626 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3627 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3628 script if and only if the first argument is `configure'. However, it
3629 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3630 scripts in the case where the package is being upgraded (see <ref
3631 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3632 that <prgn>dpkg</prgn> uses for the files while it is
3633 installing them and will make the shared library links point
3634 to them, just before <prgn>dpkg</prgn> continues the
3635 installation and removes the links!
3638 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3642 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3643 required when your package provides shared libraries.
3647 Each line is of the form:
3649 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3654 <var>library-name</var> is the name of the shared library,
3655 for example <tt>libc5</tt>.
3659 <var>version-or-soname</var> is the soname of the library -
3660 i.e., the thing that must exactly match for the library to be
3661 recognized by <prgn>ld.so</prgn>. Usually this is the major
3662 version number of the library.
3666 <var>dependencies</var> has the same syntax as a dependency
3667 field in a binary package control file. It should give
3668 details of which package(s) are required to satisfy a binary
3669 built against the version of the library contained in the
3670 package. See <ref id="depsyntax">.
3674 For example, if the package <tt>foo</tt> contains
3675 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3676 <tt>libfoo.so.1</tt>, and the first version of the package
3677 which contained a minor number of at least <tt>2.3</tt> was
3678 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3681 libfoo 1 foo (>= 1.2.3-1)
3686 The version-specific dependency is to avoid warnings from
3687 <prgn>ld.so</prgn> about using older shared libraries with
3691 <sect><heading>Further Technical information on
3692 <tt>shlibs</tt></heading>
3694 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3698 The <tt>debian/shlibs</tt> file provides a way of checking
3699 for shared library dependencies on packaged binaries.
3700 They are intended to be used by package maintainers to
3701 make their lives easier.
3705 Other <tt>shlibs</tt> files that exist on a Debian system are
3707 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3708 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3709 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3710 <item> <p><tt>debian/shlibs.local</tt></p></item>
3712 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3713 creating a binary package.</p>
3716 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3720 <prgn>dpkg-shlibdeps</prgn>
3721 determines the shared libraries directly
3724 It used to do this by calling <prgn>ldd</prgn>, but it
3725 now calls <prgn>objdump</prgn> to do this. This
3726 requires a couple of changes in the way that packages
3730 A binary <tt>foo</tt> directly uses a library
3731 <tt>libbar</tt> if it is linked with that
3732 library. Other libraries that are needed by
3733 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3734 and the dynamic linker will load them automatically
3735 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3736 lists all of the libraries used, both directly and
3737 indirectly; but <prgn>objdump</prgn> only lists the
3738 directly linked libraries. A package only needs to
3739 depend on the libraries it is directly linked to,
3740 since the dependencies for those libraries should
3741 automatically pull in the other libraries.
3744 This change does mean a change in the way packages are
3745 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3746 only run on binaries. But since we will now rely on the
3747 libraries depending on the libraries they themselves
3748 need, the packages containing those libraries will
3749 need to run <prgn>dpkg-shlibdeps</prgn> on the
3753 A good example where this would help us is the current
3754 mess with multiple version of the <tt>mesa</tt>
3755 library. With the <prgn>ldd</prgn>-based system, every
3756 package that uses <tt>mesa</tt> needs to add a
3757 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3758 to handle the glide <tt>mesa</tt> variant. With an
3759 <prgn>objdump</prgn>-based system this isn't necessary
3760 anymore and would have saved everyone a lot of work.
3763 Another example: we could update <tt>libimlib</tt>
3764 with a new version that supports a new graphics format
3765 called dgf. If we use the old <prgn>ldd</prgn> method,
3766 every package that uses <tt>libimlib</tt> would need
3767 to be recompiled so it would also depend on
3768 <tt>libdgf</tt> or it wouldn't run due to missing
3769 symbols. However with the new system, packages using
3770 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3771 having the dependency on <tt>libdgf</tt> and wouldn't
3775 used by the compiled binaries and libraries passed through
3776 on its command line.
3780 For each shared library linked to,
3781 <prgn>dpkg-shlibdeps</prgn> needs to know
3782 <list compact="compact">
3783 <item><p>the package containing the library, and</p></item>
3784 <item><p>the library version number,</p></item>
3786 and it scans the following files in this order:
3787 <enumlist compact="compact">
3788 <item><p><tt>debian/shlibs.local</tt></p></item>
3789 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3790 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3791 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3796 <sect1><heading><em>Who</em> maintains the various
3797 <tt>shlibs</tt> files?
3801 <list compact="compact">
3803 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3808 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3809 - the maintainer of each package</p>
3813 <tt>/etc/dpkg/shlibs.override</tt> - the local
3814 system administrator</p>
3817 <p><tt>debian/shlibs.local</tt> - the maintainer of
3822 The <tt>shlibs.default</tt> file is managed by
3823 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3824 that are provided by <prgn>dpkg</prgn> are just there to
3825 fix things until the shared library packages all have
3826 <tt>shlibs</tt> files.
3830 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3831 the <tt>shlibs</tt> files
3834 <sect2><heading>If your package doesn't provide a shared
3839 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3840 <tt>debian/rules</tt> file. If your package contains
3841 only binaries (e.g. no scripts) use:
3843 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3845 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3846 done. If it does complain you might need to create your
3847 own <tt>debian/shlibs.local</tt> file.</p>
3850 <sect2><heading>If your package provides a shared library
3854 Create a <tt>debian/shlibs</tt> file and let
3855 <tt>debian/rules</tt> install it in the control area:
3857 install -m644 debian/shlibs debian/tmp/DEBIAN
3859 If your package contains additional binaries see above.
3864 <sect1><heading><em>How</em> to write
3865 <tt>debian/shlibs.local</tt>
3869 This file is intended only as a <em>temporary</em> fix if
3870 your binaries depend on a library which doesn't provide
3871 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3875 Let's assume you are packaging a binary <tt>foo</tt>. Your
3876 output in building the package might look like this.
3879 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3880 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3881 libc.so.6 => /lib/libc.so.6 (0x40114000)
3882 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3884 And when you ran <prgn>dpkg-shlibdeps</prgn>
3886 $ dpkg-shlibdeps -O foo
3887 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3888 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3889 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3891 The <prgn>foo</prgn> binary depends on the
3892 <prgn>libbar</prgn> shared library, but no package seems
3893 to provide a <tt>*.shlibs</tt> file in
3894 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3900 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3901 bar1: /usr/X11R6/lib/libbar.so.1.0
3902 $ dpkg -s bar1 | grep Version
3905 This tells us that the <prgn>bar1</prgn> package, version
3906 1.0-1 is the one we are using. Now we can create our own
3907 <tt>debian/shlibs.local</tt> to temporarily fix the above
3908 problem. Include the following line into your
3909 <tt>debian/shlibs.local</tt> file.
3911 libbar 1 bar1 (>= 1.0-1)
3913 Now your package build should work. As soon as the
3914 maintainer of <prgn>libbar1</prgn> provides a
3915 <tt>shlibs</tt> file, you can remove your
3916 <tt>debian/shlibs.local</tt> file.
3922 <chapt><heading>The Operating System</heading>
3926 <heading>File system hierarchy</heading>
3930 <heading>Linux File system Structure</heading>
3933 The location of all installed files and directories must
3934 comply with the Linux File system Hierarchy Standard
3935 (FHS). The latest version of this document can be found
3936 alongside this manual or on
3937 <url id="http://www.pathname.com/fhs/">.
3938 Specific questions about following the standard may be
3939 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3940 Quinlan, the FHS coordinator, at
3941 <email>quinlan@pathname.com</email>.</p></sect1>
3945 <heading>Site-specific programs</heading>
3948 As mandated by the FHS, packages must not place any
3949 files in <tt>/usr/local</tt>, either by putting them in
3950 the file system archive to be unpacked by <prgn>dpkg</prgn>
3951 or by manipulating them in their maintainer scripts.</p>
3954 However, the package may create empty directories below
3955 <tt>/usr/local</tt> so that the system administrator knows
3956 where to place site-specific files. These directories
3957 should be removed on package removal if they are
3961 Note, that this applies only to directories <em>below</em>
3962 <tt>/usr/local</tt>, not <em>in</em>
3963 <tt>/usr/local</tt>. Packages must not create sub-directories
3964 in the directory <tt>/usr/local</tt> itself, except those listed in
3965 FHS, section 4.5. However, you may create directories
3966 below them as you wish. You must not remove any of the
3967 directories listed in 4.5, even if you created them.</p>
3970 Since <tt>/usr/local</tt> can be mounted read-only from a
3971 remote server, these directories must be created and
3972 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3973 maintainer scripts. These scripts must not fail if either
3974 of these operations fail. (In the future, it will be
3975 possible to tell <prgn>dpkg</prgn> not to unpack files
3976 matching certain patterns, so that the directories can be
3977 included in the <tt>.deb</tt> packages and system
3978 administrators who do not wish these directories in
3979 /usr/local do not need to have them.)</p>
3982 For example, the <prgn>emacs</prgn> package will contain
3984 mkdir -p /usr/local/lib/emacs/site-lisp || true
3986 in the <tt>postinst</tt> script, and
3988 rmdir /usr/local/lib/emacs/site-lisp || true
3989 rmdir /usr/local/lib/emacs || true
3991 in the <tt>prerm</tt> script.</p>
3994 If you do create a directory in <tt>/usr/local</tt> for
3995 local additions to a package, you should ensure that
3996 settings in <tt>/usr/local</tt> take precedence over the
3997 equivalents in <tt>/usr</tt>.</p>
4000 However, because '/usr/local' and its contents are for
4001 exclusive use of the local administrator, a package must
4002 not rely on the presence or absence of files or
4003 directories in '/usr/local' for normal operation.</p>
4006 The <tt>/usr/local</tt> directory itself and all the
4007 subdirectories created by the package should (by default) have
4008 permissions 2775 (group-writable and set-group-id) and be
4009 owned by <tt>root.staff</tt>.</p>
4014 <heading>Users and groups</heading>
4017 The Debian system can be configured to use either plain or
4018 shadow passwords.</p>
4021 Some user ids (UIDs) and group ids (GIDs) are reserved
4022 globally for use by certain packages. Because some packages
4023 need to include files which are owned by these users or
4024 groups, or need the ids compiled into binaries, these ids
4025 must be used on any Debian system only for the purpose for
4026 which they are allocated. This is a serious restriction, and
4027 we should avoid getting in the way of local administration
4028 policies. In particular, many sites allocate users and/or
4029 local system groups starting at 100.</p>
4032 Apart from this we should have dynamically allocated ids,
4033 which should by default be arranged in some sensible
4034 order--but the behavior should be configurable.</p>
4037 Packages other than <tt>base-passwd</tt> must not modify
4038 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4039 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4042 The UID and GID ranges are as follows:
4047 Globally allocated by the Debian project, the
4048 same on every Debian system. These ids will appear in
4049 the <tt>passwd</tt> and <tt>group</tt> files of all
4050 Debian systems, new ids in this range being added
4051 automatically as the <tt>base-passwd</tt> package is
4055 Packages which need a single statically allocated uid
4056 or gid should use one of these; their maintainers
4057 should ask the <tt>base-passwd</tt> maintainer for
4064 Dynamically allocated system users and groups.
4065 Packages which need a user or group, but can have this
4066 user or group allocated dynamically and differently on
4067 each system, should use `<tt>adduser --system</tt>' to
4068 create the group and/or user. <prgn>adduser</prgn>
4069 will check for the existence of the user or group, and
4070 if necessary choose an unused id based on the ranges
4071 specified in <tt>adduser.conf</tt>.</p></item>
4074 <tag>1000-29999:</tag>
4077 Dynamically allocated user accounts. By default
4078 <prgn>adduser</prgn> will choose UIDs and GIDs for
4079 user accounts in this range, though
4080 <tt>adduser.conf</tt> may be used to modify this
4084 <tag>30000-59999:</tag>
4086 <p>Reserved.</p></item>
4089 <tag>60000-64999:</tag>
4092 Globally allocated by the Debian project, but only
4093 created on demand. The ids are allocated centrally and
4094 statically, but the actual accounts are only created
4095 on users' systems on demand.</p>
4098 These ids are for packages which are obscure or which
4099 require many statically-allocated ids. These packages
4100 should check for and create the accounts in
4101 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4102 <prgn>adduser</prgn> if it has this facility) if
4103 necessary. Packages which are likely to require
4104 further allocations should have a `hole' left after
4105 them in the allocation, to give them room to
4109 <tag>65000-65533:</tag>
4111 <p>Reserved.</p></item>
4116 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4117 to the group `<tt>nogroup</tt>.'</p></item>
4123 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4124 because it is the error return sentinel value.</p>
4129 <sect id="sysvinit">
4130 <heading>System run levels</heading>
4133 <sect1 id="/etc/init.d">
4134 <heading>Introduction</heading>
4137 The <tt>/etc/init.d</tt> directory contains the scripts
4138 executed by <prgn>init</prgn> at boot time and when init
4139 state (or `runlevel') is changed (see <manref name="init"
4143 There are at least two different, yet functionally
4144 equivalent, ways of handling these scripts. For the sake
4145 of simplicity, this document describes only the symbolic
4146 link method. However, it must not be assumed by maintainer
4147 scripts that this method is being used, and any automated
4148 manipulation of the various runlevel behaviours by
4149 maintainer scripts must be performed using `update-rc.d'
4150 as described below and not by manually installing or
4151 removing symlinks. For information on the
4152 implementation details of the other method, implemented in
4153 the <tt>file-rc</tt> package, please refer to the
4154 documentation of that package.</p>
4157 These scripts are referenced by symbolic links in
4158 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4159 changing runlevels, <prgn>init</prgn> looks in the
4160 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4161 it should execute, where <var>n</var> is the runlevel that
4162 is being changed to, or `S' for the boot-up scripts.</p>
4165 The names of the links all have the form
4166 <tt>S<var>mm</var><var>script</var></tt> or
4167 <tt>K<var>mm</var><var>script</var></tt> where
4168 <var>mm</var> is a two-digit number and <var>script</var>
4169 is the name of the script (this should be the same as the
4170 name of the actual script in <tt>/etc/init.d</tt>.</p>
4173 When <prgn>init</prgn> changes runlevel first the targets
4174 of the links whose names starting with a <tt>K</tt> are
4175 executed, each with the single argument <tt>stop</tt>,
4176 followed by the scripts prefixed with an <tt>S</tt>, each
4177 with the single argument <tt>start</tt>. The <tt>K</tt>
4178 links are responsible for killing services and the
4179 <tt>S</tt> link for starting services upon entering the
4183 For example, if we are changing from runlevel 2 to
4184 runlevel 3, init will first execute all of the <tt>K</tt>
4185 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4186 all of the <tt>S</tt> prefixed scripts. The links
4187 starting with <tt>K</tt> will cause the referred-to file
4188 to be executed with an argument of <tt>stop</tt>, and the
4189 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4192 The two-digit number <var>mm</var> is used to decide which
4193 order to start and stop things in--low-numbered links have
4194 their scripts run first. For example, the <tt>K20</tt>
4195 scripts will be executed before the <tt>K30</tt> scripts.
4196 This is used when a certain service must be started before
4197 another. For example, the name server <prgn>bind</prgn>
4198 might need to be started before the news server
4199 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4200 access lists. In this case, the script that starts
4201 <prgn>bind</prgn> would have a lower number than the
4202 script that starts <prgn>inn</prgn> so that it runs first:
4211 <heading>Writing the scripts</heading>
4214 Packages that include daemons for system services should
4215 place scripts in <tt>/etc/init.d</tt> to start or stop
4216 services at boot time or during a change of runlevel.
4217 These scripts should be named
4218 <tt>/etc/init.d/<var>package</var></tt>, and they should
4219 accept one argument, saying what to do:
4222 <tag><tt>start</tt></tag>
4223 <item><p>start the service,</p></item>
4225 <tag><tt>stop</tt></tag>
4226 <item><p>stop the service,</p></item>
4228 <tag><tt>restart</tt></tag>
4229 <item><p>stop and restart the service,</p></item>
4231 <tag><tt>reload</tt></tag>
4232 <item><p>cause the configuration of the service to be
4233 reloaded without actually stopping and restarting
4234 the service,</p></item>
4236 <tag><tt>force-reload</tt></tag> <item><p>cause the
4237 configuration to be reloaded if the service supports
4238 this, otherwise restart the service.</p></item>
4241 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4242 <tt>force-reload</tt> options should be supported by all
4243 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4244 option is optional.</p>
4247 The <tt>init.d</tt> scripts should ensure that they will
4248 behave sensibly if invoked with <tt>start</tt> when the
4249 service is already running, or with <tt>stop</tt> when it
4250 isn't, and that they don't kill unfortunately-named user
4251 processes. The best way to achieve this is usually to use
4252 <prgn>start-stop-daemon</prgn>.</p>
4255 If a service reloads its configuration automatically (as
4256 in the case of <prgn>cron</prgn>, for example), the
4257 <tt>reload</tt> option of the <tt>init.d</tt> script
4258 should behave as if the configuration has been reloaded
4262 These scripts should not fail obscurely when the
4263 configuration files remain but the package has been
4264 removed, as configuration files remain on the system after
4265 the package has been removed. Only when <prgn>dpkg</prgn>
4266 is executed with the <tt>--purge</tt> option will
4267 configuration files be removed. In particular, the init
4268 script itself is usually a configuration file (see
4269 <ref id="init.d notes">), and will remain on the system if
4270 the package is removed but not purged. Therefore, you
4271 should include a <tt>test</tt> statement at the top of the
4274 test -f <var>program-executed-later-in-script</var> || exit 0
4278 Often there are some values in the `<tt>init.d</tt>'
4279 scripts that a system administrator will frequently want
4280 to change. While the scripts are frequently conffiles,
4281 modifying them requires that the administrator merge in
4282 their changes each time the package is upgraded and the
4283 conffile changes. To ease the burden on the system
4284 administrator, such configurable values should not be
4285 placed directly in the script. Instead, they should be
4286 placed in a file in `<tt>/etc/default</tt>', which
4287 typically will have the same base name as the
4288 `<tt>init.d</tt>' script. This extra file can be sourced
4289 by the script when the script runs. It must contain only
4290 variable settings and comments.
4294 To ensure that vital configurable values are always
4295 available, the `<tt>init.d</tt>' script should set default
4296 values for each of the shell variables it uses before
4297 sourcing the <tt>/etc/default/</tt> file. Also, since the
4298 `<tt>/etc/default/</tt>' file is often a conffile, the
4299 `<tt>init.d</tt>' script must behave sensibly without
4300 failing if it is deleted.
4306 <heading>Managing the links</heading>
4309 The program <prgn>update-rc.d</prgn> is provided to make
4310 it easier for package maintainers to arrange for the
4311 proper creation and removal of
4312 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4313 functional equivalent if another method is being used.
4314 This may be used by maintainers in their packages'
4315 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4318 You must use this script to make changes to
4319 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4320 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4321 in the actual archive or manually create or remove the
4322 symbolic links in maintainer scripts. (The latter will
4323 fail if an alternative method of maintaining runlevel
4324 information is being used.)</p>
4327 By default <prgn>update-rc.d</prgn> will start services in
4328 each of the multi-user state runlevels (2, 3, 4, and 5)
4329 and stop them in the halt runlevel (0), the single-user
4330 runlevel (1) and the reboot runlevel (6). The system
4331 administrator will have the opportunity to customize
4332 runlevels by either running <prgn>update-rc.d</prgn>, by
4333 simply adding, moving, or removing the symbolic links in
4334 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4335 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4336 <tt>file-rc</tt> method is being used.</p>
4339 To get the default behavior for your package, put in your
4340 <tt>postinst</tt> script
4342 update-rc.d <var>package</var> defaults >/dev/null
4344 and in your <tt>postrm</tt>
4346 if [ purge = "$1" ]; then
4347 update-rc.d <var>package</var> remove >/dev/null
4352 This will use a default sequence number of 20. If it does
4353 not matter when or in which order the script is run, use
4354 this default. If it does, then you should talk to the
4355 maintainer of the <prgn>sysvinit</prgn> package or post to
4356 <tt>debian-devel</tt>, and they will help you choose a
4360 For more information about using <tt>update-rc.d</tt>,
4361 please consult its manpage <manref name="update-rc.d"
4362 section="8">.</p></sect1>
4366 <heading>Boot-time initialization</heading>
4369 There used to be another directory, <tt>/etc/rc.boot</tt>,
4370 which contained scripts which were run once per machine
4371 boot. This has been deprecated in favour of links from
4372 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4373 described in <ref id="/etc/init.d">. Packages must not
4374 place files in <tt>/etc/rc.boot</tt>.</p>
4376 <sect1 id="init.d notes">
4377 <heading>Notes</heading>
4380 <em>Do not</em> include the
4381 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4382 <tt>.deb</tt> file system archive! <em>This will cause
4383 problems!</em> You must create them with
4384 <prgn>update-rc.d</prgn>, as above.</p>
4387 <em>Do not</em> include the
4388 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4389 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4390 problems!</em> You should, however, treat the
4391 <tt>/etc/init.d</tt> scripts as configuration files,
4392 either by marking them as conffiles or managing them
4393 correctly in the maintainer scripts (see
4394 <ref id="config files">). (This is important since we want
4395 to give the local system administrator the chance to adapt
4396 the scripts to the local system--e.g., to disable a
4397 service without de-installing the package, or to specify
4398 some special command line options when starting a
4399 service--while making sure her changes aren't lost during
4400 the next package upgrade.)</p>
4404 <heading>Example</heading>
4407 The <prgn>bind</prgn> DNS (nameserver) package wants to
4408 make sure that the nameserver is running in multiuser
4409 runlevels, and is properly shut down with the system. It
4410 puts a script in <tt>/etc/init.d</tt>, naming the script
4411 appropriately <tt>bind</tt>. As you can see, the script
4412 interprets the argument <tt>reload</tt> to send the
4413 nameserver a <tt>HUP</tt> signal (causing it to reload its
4414 configuration); this way the user can say
4415 <tt>/etc/init.d/bind reload</tt> to reload the name
4416 server. The script has one configurable value, which can
4417 be used to pass parameters to the named program at
4425 # Original version by Robert Leslie
4426 # <rob@mars.org>, edited by iwj and cs
4428 test -x /usr/sbin/named || exit 0
4430 # Source defaults file.
4432 if [ -f /etc/default/bind ]; then
4439 echo -n "Starting domain name service: named"
4440 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4445 echo -n "Stopping domain name service: named"
4446 start-stop-daemon --stop --quiet \
4447 --pidfile /var/run/named.pid --exec /usr/sbin/named
4451 echo -n "Restarting domain name service: named"
4452 start-stop-daemon --stop --quiet \
4453 --pidfile /var/run/named.pid --exec /usr/sbin/named
4454 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4458 force-reload|reload)
4459 echo -n "Reloading configuration of domain name service: named"
4460 start-stop-daemon --stop --signal 1 --quiet \
4461 --pidfile /var/run/named.pid --exec /usr/sbin/named
4465 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4475 Complementing the above init script is a file
4476 '<tt>/etc/default/bind</tt>', which contains configurable
4477 parameters used by the script.
4481 # Specified parameters to pass to named. See named(8).
4482 # You may uncomment the following line, and edit to taste.
4488 Another example on which to base your <tt>/etc/init.d</tt>
4489 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4492 If this package is happy with the default setup from
4493 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4494 and having named running in all runlevels, it can say in
4495 its <tt>postinst</tt>:
4497 update-rc.d bind defaults >/dev/null
4499 And in its <tt>postrm</tt>, to remove the links when the
4502 if [ purge = "$1" ]; then
4503 update-rc.d bind remove >/dev/null
4509 <heading>Cron jobs</heading>
4512 Packages must not modify the configuration file
4513 <tt>/etc/crontab</tt>, and they must not modify the files in
4514 <tt>/var/spool/cron/crontabs</tt>.</p>
4517 If a package wants to install a job that has to be executed
4518 via cron, it should place a file with the name of the
4519 package in one of the following directories:
4525 As these directory names imply, the files within them are
4526 executed on a daily, weekly, or monthly basis,
4527 respectively. The exact times are listed in
4528 <tt>/etc/crontab</tt>.</p>
4531 All files installed in any of these directories must be
4532 scripts (shell scripts, Perl scripts, etc.) so that they can
4533 easily be modified by the local system administrator. In
4534 addition, they should be treated as configuration files.</p>
4537 If a certain job has to be executed more frequently than
4538 daily, the package should install a file
4539 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4540 the same syntax as <tt>/etc/crontab</tt> and is processed by
4541 <prgn>cron</prgn> automatically. The file must also be
4542 treated as a configuration file. (Note, that entries in the
4543 <tt>/etc/cron.d</tt> directory are not handled by
4544 <prgn>anacron</prgn>. Thus, you should only use this
4545 directory for jobs which may be skipped if the system is not
4549 The scripts or crontab entries in these directories should
4550 check if all necessary programs are installed before they
4551 try to execute them. Otherwise, problems will arise when a
4552 package was removed but not purged since configuration files
4553 are kept on the system in this situation.</p>
4557 <heading>Console messages</heading>
4560 This section describes different formats for messages
4561 written to standard output by the <tt>/etc/init.d</tt>
4562 scripts. The intent is to improve the consistency of
4563 Debian's startup and shutdown look and feel.</p>
4566 Please look very careful at the details. We want to get the
4567 messages to look exactly the same way concerning spaces,
4568 punctuation, and case of letters.</p>
4571 Here is a list of overall rules that you should use when you
4572 create output messages. They can be useful if you have a
4573 non-standard message that isn't covered in the sections
4580 Every message should cover one line, start with a
4581 capital letter and end with a period `.'.</p></item>
4586 If you want to express that the computer is working on
4587 something (performing a specific task, not starting or
4588 stopping a program), we use an ``ellipsis'', namely
4589 three dots `...'. Note that we don't insert spaces in
4590 front of or behind the dots. If the task has been
4591 completed we write `done.' and a line feed.</p></item>
4596 Design your messages as if the computer is telling you
4597 what he is doing (let him be polite :-) but don't
4598 mention ``him'' directly. For example, if you think
4601 I'm starting network daemons: nfsd mountd.
4605 Starting network daemons: nfsd mountd.
4606 </example></p></item>
4610 The following formats should be used</p>
4615 <p>when daemons get started.</p>
4618 Use this format if your script starts one or more
4619 daemons. The output should look like this (a single
4620 line, no leading spaces):
4622 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4624 The <description> should describe the subsystem
4625 the daemon or set of daemons are part of, while
4626 <daemon-1> up to <daemon-n> denote each
4627 daemon's name (typically the file name of the
4631 For example, the output of /etc/init.d/lpd would look like:
4633 Starting printer spooler: lpd.
4637 This can be achieved by saying
4639 echo -n "Starting printer spooler: lpd"
4640 start-stop-daemon --start --quiet lpd
4643 in the script. If you have more than one daemon to
4644 start, you should do the following:
4646 echo -n "Starting remote file system services:"
4647 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4648 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4649 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4652 This makes it possible for the user to see what takes
4653 so long and when the final daemon has been
4654 started. You should be careful where to put spaces: In the
4655 example above the system administrator can easily
4656 comment out a line if he don't wants to start a
4657 specific daemon, while the displayed message still
4658 looks good.</p></item>
4662 <p>when something needs to be configured.</p>
4665 If you have to set up different parameters of the
4666 system upon boot up, you should use this format:
4668 Setting <parameter> to `<value>'.
4672 You can use the following echo statement to get the quotes right:
4674 echo "Setting DNS domainname to \`"value"'."
4678 Note that the left quotation mark (`) is different
4679 from the right (').</p></item>
4682 <p>when a daemon is stopped.</p>
4685 When you stop a daemon you should issue a message
4686 similar to the startup message, except that `Starting'
4687 is replaced with `Stopping'.</p>
4690 So stopping the printer daemon will like like this:
4692 Stopping printer spooler: lpd.
4693 </example></p></item>
4696 <p>when something is executed.</p>
4699 There are several examples where you have to run a
4700 program at system startup or shutdown to perform a
4701 specific task. For example, setting the system's clock
4702 via `netdate' or killing all processes when the system
4703 comes down. Your message should like this:
4705 Doing something very useful...done.
4707 You should print the `done.' right after the job has been completed,
4708 so that the user gets informed why he has to wait. You can get this
4711 echo -n "Doing something very useful..."
4715 in your script.</p></item>
4718 <p>when the configuration is reloaded.</p>
4721 When a daemon is forced to reload its configuration
4722 files you should use the following format:
4724 Reloading <daemon's-name> configuration...done.
4725 </example></p></item>
4728 <p>when none of the above rules apply.</p>
4731 If you have to print a message that doesn't fit into
4732 the styles described above, you can use something
4733 appropriate, but please have a look at the overall
4734 rules listed above.</p></item>
4739 <heading>Menus</heading>
4742 Menu entries should follow the current menu policy as
4743 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4744 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4745 or your local mirror. In addition, it is included in the
4746 <tt>debian-policy</tt> package.
4750 The Debian <tt>menu</tt> packages provides a unique
4751 interface between packages providing applications and
4752 documents, and <em>menu programs</em> (either X window
4753 managers or text-based menu programs as
4754 <prgn>pdmenu</prgn>).</p>
4757 All packages that provide applications that need not be
4758 passed any special command line arguments for normal
4759 operation should register a menu entry for those
4760 applications, so that users of the <tt>menu</tt> package
4761 will automatically get menu entries in their window
4762 managers, as well in shells like <tt>pdmenu</tt>.</p>
4765 Please refer to the <em>Debian Menu System</em> document
4766 that comes with the <tt>menu</tt> package for information
4767 about how to register your applications and web
4773 <heading>Multimedia handlers</heading>
4776 Packages which provide the ability to view/show/play,
4777 compose, edit or print MIME types should register themselves
4778 as such following the current MIME support policy as defined
4779 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4780 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4781 or your local mirror. In addition, it is included in the
4782 <tt>debian-policy</tt> package.
4786 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4787 mechanism for encoding files and data streams and providing
4788 meta-information about them, in particular their type (e.g.
4789 audio or video) and format (e.g. PNG, HTML, MP3).
4793 Registration of MIME type handlers allows programs like mail
4794 user agents and web browsers to to invoke these handlers to
4795 view, edit or display MIME types they don't support
4801 <heading>Keyboard configuration</heading>
4804 To achieve a consistent keyboard configuration (i.e., all
4805 applications interpret a keyboard event the same way) all
4806 programs in the Debian distribution must be configured to
4807 comply with the following guidelines.</p>
4810 Here is a list that contains certain keys and their interpretation:
4813 <tag><tt><--</tt></tag>
4814 <item><p>delete the character to the left of the cursor</p></item>
4816 <tag><tt>Delete</tt></tag>
4817 <item><p>delete the character to the right of the cursor</p></item>
4819 <tag><tt>Control+H</tt></tag>
4820 <item><p>emacs: the help prefix</p></item>
4823 The interpretation of any keyboard events should be independent
4824 of the terminal that's used, be it a virtual console, an X
4825 terminal emulator, an rlogin/telnet session, etc.</p>
4828 The following list explains how the different programs
4829 should be set up to achieve this:</p>
4832 <list compact="compact">
4833 <item><p>`<tt><--</tt>' generates KB_Backspace in
4836 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4840 X translations are set up to make KB_Backspace
4841 generate ASCII DEL, and to make KB_Delete generate
4842 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4843 the `delete character' key). This must be done by
4844 loading the resources using xrdb on all local X
4845 displays, not using the application defaults, so that
4846 the translation resources used correspond to the
4847 xmodmap settings.</p></item>
4851 The Linux console is configured to make
4852 `<tt><--</tt>' generate DEL, and `Delete' generate
4853 <tt>ESC [ 3 ~</tt> (this is the case at the
4857 X applications are configured so that Backspace
4858 deletes left, and Delete deletes right. Motif
4859 applications already work like this.</p></item>
4861 <item><p>stty erase <tt>^?</tt> .</p></item>
4864 The `xterm' terminfo entry should have <tt>ESC [ 3
4865 ~</tt> for kdch1, just like TERM=linux and
4866 TERM=vt220.</p></item>
4869 Emacs is programmed to map KB_Backspace or the `stty
4870 erase' character to delete-backward-char, and
4871 KB_Delete or kdch1 to delete-forward-char, and
4872 <tt>^H</tt> to help as always.</p></item>
4875 Other applications use the `stty erase' character and
4876 kdch1 for the two delete keys, with ASCII DEL being
4877 `delete previous character' and kdch1 being `delete
4878 character under cursor'.</p></item>
4882 This will solve the problem except for:</p>
4885 <list compact="compact">
4887 Some terminals have a <tt><--</tt> key that cannot
4888 be made to produce anything except <tt>^H</tt>. On
4889 these terminals Emacs help will be unavailable on
4890 <tt>^H</tt> (assuming that the `stty erase' character
4891 takes precedence in Emacs, and has been set
4892 correctly). M-x help or F1 (if available) can be used
4896 Some operating systems use <tt>^H</tt> for stty erase.
4897 However, modern telnet versions and all rlogin
4898 versions propagate stty settings, and almost all UNIX
4899 versions honour stty erase. Where the stty settings
4900 are not propagated correctly things can be made to
4901 work by using stty manually.</p></item>
4904 Some systems (including previous Debian versions) use
4905 xmodmap to arrange for both <tt><--</tt> and Delete
4906 to generate KB_Delete. We can change the behavior
4907 of their X clients via the same X resources that we
4908 use to do it for our own, or have our clients be
4909 configured via their resources when things are the
4910 other way around. On displays configured like this
4911 Delete will not work, but <tt><--</tt>
4915 Some operating systems have different kdch1 settings
4916 in their terminfo for xterm and others. On these
4917 systems the Delete key will not work correctly when
4918 you log in from a system conforming to our policy, but
4919 <tt><--</tt> will.</p></item>
4926 <heading>Environment variables</heading>
4929 A program must not depend on environment variables to get
4930 reasonable defaults. (That's because these environment
4931 variables would have to be set in a system-wide
4932 configuration file like /etc/profile, which is not supported
4936 If a program usually depends on environment variables for its
4937 configuration, the program should be changed to fall back to
4938 a reasonable default configuration if these environment
4939 variables are not present. If this cannot be done easily
4940 (e.g., if the source code of a non-free program is not
4941 available), the program must be replaced by a small
4942 `wrapper' shell script which sets the environment variables
4943 if they are not already defined, and calls the original program.</p>
4946 Here is an example of a wrapper script for this purpose:
4950 BAR=${BAR:-/var/lib/fubar}
4952 exec /usr/lib/foo/foo "$@"
4956 Furthermore, as <tt>/etc/profile</tt> is a configuration
4957 file of the <prgn>base-files</prgn> package, other packages must not
4958 put any environment variables or other commands into that
4963 <heading>Files</heading>
4967 <heading>Binaries</heading>
4970 Two different packages must not install programs with
4971 different functionality but with the same filenames. (The
4972 case of two programs having the same functionality but
4973 different implementations is handled via `alternatives.')
4974 If this case happens, one of the programs must be
4975 renamed. The maintainers should report this to the
4976 developers' mailing and try to find a consensus about
4977 which package will have to be renamed. If a consensus can
4978 not be reached, <em>both</em> programs must be
4982 Generally the following compilation parameters should be used:
4985 CFLAGS = -O2 -Wall # sane warning options vary between programs
4987 install -s # (or use strip on the files in debian/tmp)
4991 Note that by default all installed binaries should be stripped,
4992 either by using the <tt>-s</tt> flag to
4993 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4994 the binaries after they have been copied into
4995 <tt>debian/tmp</tt> but before the tree is made into a
4999 The <tt>-N</tt> flag should not be used. On a.out systems
5000 it may have been useful for some very small binaries, but
5001 for ELF it has no good effect.</p>
5004 Debugging symbols are useful for error diagnosis,
5005 investigation of core dumps (which may be submitted by users
5006 in bug reports), or testing and developing the
5007 software. Therefore it is recommended to support building
5008 the package with debugging information through the following
5009 interface: If the environment variable
5010 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5011 <tt>debug</tt>, compile the software with debugging
5012 information (usually this involves adding the <tt>-g</tt>
5013 flag to <tt>CFLAGS</tt>). This allows the generation of a
5014 build tree with debugging information. If the environment
5015 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5016 <tt>nostrip</tt>, do not strip the files at installation
5017 time. This allows one to generate a package with debugging
5018 information included. The following makefile snippet is only
5019 an example of how one may test for either condition:
5022 Rationale: Building by default with -g causes more
5023 wasted CPU cycles since the information is stripped away
5024 anyway. The package can by default build without -g if
5025 it also provides a mechanism to easily be rebuilt with
5026 debugging information. This can be done by providing a
5027 "build-debug" make target, or allowing the user to
5028 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5029 compiling that package.
5031 <p>Now this has several added benefits:
5035 It is actually easier to build debugging bins and
5036 libraries this way (no more editing debian/rules
5037 or similar) since it provides a documented way of
5038 getting this type of build.</p>
5042 There will be much less wasted CPU time for the
5043 autobuilders since not having debugging
5044 information (and hence also not having to strip
5045 it) will increase the speed of compiles. This
5046 skips an entire pass of the compiler.
5057 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5058 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5059 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5060 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5062 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5065 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5066 INSTALL_PROGRAM += -s
5070 Please note that the above example is merely informative,
5071 and is not a policy mandate. You may have to massage this
5072 example in order to make it work for your package.
5077 It is up to the package maintainer to decide what
5078 compilation options are best for the package. Certain
5079 binaries (such as computationally-intensive programs) will
5080 function better with certain flags (<tt>-O3</tt>, for
5081 example); feel free to use them. Please use good judgment
5082 here. Don't use flags for the sake of it; only use them
5083 if there is good reason to do so. Feel free to override
5084 the upstream author's ideas about which compilation
5085 options are best--they are often inappropriate for our
5086 environment.</p></sect>
5090 <heading>Libraries</heading>
5093 All libraries must have a shared version in the lib
5094 package and a static version in the lib-dev package. The
5095 shared version must be compiled with <tt>-fPIC</tt>, and
5096 the static version must not be. In other words, each
5097 <tt>*.c</tt> file will need to be compiled twice.</p>
5100 You must specify the gcc option <tt>-D_REENTRANT</tt>
5101 when building a library (either static or shared) to make
5102 the library compatible with LinuxThreads.</p>
5105 Note that all installed shared libraries should be
5108 strip --strip-unneeded <your-lib>
5110 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5111 only the symbols which aren't needed for relocation
5112 processing.) Shared libraries can function perfectly well
5113 when stripped, since the symbols for dynamic linking are
5114 in a separate part of the ELF object file.</p>
5117 Note that under some circumstances it may be useful to
5118 install a shared library unstripped, for example when
5119 building a separate package to support debugging.
5123 An ever increasing number of packages are using libtool to
5124 do their linking. The latest GNU libtools (>= 1.3a) can take
5125 advantage of the metadata in the installed libtool archive
5126 files (`*.la'). The main advantage of libtool's .la files is
5127 that it allows libtool to store and subsequently access
5128 metadata with respect to the libraries it builds. libtool
5129 will search for those files, which contain a lot of useful
5130 information about a library (e.g. dependency libraries for
5131 static linking). Also, they're <em>essential</em> for
5132 programs using libltdl.
5136 Certainly libtool is fully capable of linking against shared
5137 libraries which don't have .la files, but being a mere shell
5138 script it can add considerably to the build time of a
5139 libtool using package if that shell-script has to derive all
5140 this information from first principles for each library every
5141 time it is linked. With the advent of libtool-1.4 (and to a
5142 lesser extent libtool-1.3), the .la files will also store
5143 information about inter-library dependencies which cannot
5144 necessarily be derived after the .la file is deleted.
5148 Packages that use libtool to create shared libraries should
5149 include the <em>.la</em> files in the <em>-dev</em>
5150 packages, with the exception that if the package relies on
5151 libtool's <em>libltdl</em> library, in which case the .la
5152 files must go in the run-time library package. This is a
5153 good idea in general, and especially for static linking
5158 You must make sure that you use only released versions of
5159 shared libraries to build your packages; otherwise other
5160 users will not be able to run your binaries
5161 properly. Producing source packages that depend on
5162 unreleased compilers is also usually a bad
5169 <heading>Shared libraries</heading>
5172 Packages involving shared libraries should be split up
5173 into several binary packages.</p>
5176 For a straightforward library which has a development
5177 environment and a runtime kit including just shared
5178 libraries you need to create two packages:
5179 <tt><var>libraryname</var><var>soname</var></tt>
5180 (<var>soname</var> is the shared object name of the shared
5181 library--it's the thing that has to match exactly between
5182 building an executable and running it for the dynamic
5183 linker to be able run the program; usually the
5184 <var>soname</var> is the major number of the library) and
5185 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5188 If you prefer only to support one development version at a
5189 time you may name the development package
5190 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5191 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5192 ensure that the user only installs one development version
5193 at a time (after all, different development versions are
5194 likely to have the same header files in them, causing a
5195 filename clash if both are installed). Typically the
5196 development version should also have an exact version
5197 dependency on the runtime library, to make sure that
5198 compilation and linking happens correctly.</p>
5201 Packages which use the shared library should have a
5202 dependency on the name of the shared library package,
5203 <tt><var>libraryname</var><var>soname</var></tt>. When
5204 the <var>soname</var> changes you can have both versions
5205 of the library installed while moving from the old library
5209 If your package has some run-time support programs which
5210 use the shared library you must not put them in
5211 the shared library package. If you do that then you won't
5212 be able to install several versions of the shared library
5213 without getting filename clashes. Instead, either create
5214 a third package for the runtime binaries (this package
5215 might typically be named
5216 <tt><var>libraryname</var>-runtime</tt>--note the absence
5217 of the <var>soname</var> in the package name) or if the
5218 development package is small include them in there.</p>
5221 If you have several shared libraries built from the same
5222 source tree you may lump them all together into a single
5223 shared library package, provided that you change all their
5224 <var>soname</var>s at once (so that you don't get filename
5225 clashes if you try to install different versions of the
5226 combined shared libraries package).</p>
5229 You should follow the directions in the <em>Debian Packaging
5230 Manual</em> for putting the shared library in its package,
5231 and you must include a <tt>shlibs</tt> control area
5232 file with details of the dependencies for packages which
5233 use the library.</p>
5236 Shared libraries should not be installed
5237 executable, since <prgn>ld.so</prgn> does not require this
5238 and trying to execute a shared library results in a core
5243 <heading>Scripts</heading>
5246 All command scripts, including the package maintainer
5247 scripts inside the package and used by <prgn>dpkg</prgn>,
5248 should have a <tt>#!</tt> line naming the shell to be used
5249 to interpret them.</p>
5252 In the case of Perl scripts this should be
5253 <tt>#!/usr/bin/perl</tt>.</p>
5256 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5257 should almost certainly start with <tt>set -e</tt> so that
5258 errors are detected. Every script should use
5259 <tt>set -e</tt> or check the exit status of <em>every</em>
5263 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5264 symbolic link to any POSIX compatible shell, if <tt>echo
5265 -n</tt> does not generate a newline.
5268 Debian policy specifies POSIX behavior for /bin/sh, but
5269 echo -n has widespread use in the Linux community
5270 (including especially debian policy, the linux kernel
5271 source, many debian scripts, etc.). This echo -n
5272 mechanism is valid but not required under POSIX, hence
5273 this explicit addition. Also, rumour has it that this
5274 shall be mandated under the LSB anyway.
5278 specifying `<tt>/bin/sh</tt>' as interpreter should only
5279 use POSIX features. If a script requires non-POSIX
5280 features from the shell interpreter, the appropriate shell
5281 must be specified in the first line of the script (e.g.,
5282 `<tt>#!/bin/bash</tt>') and the package must depend on the
5283 package providing the shell (unless the shell package is
5284 marked `Essential', e.g., in the case of
5289 You may wish to restrict your script to POSIX features when possible so
5290 that it may use <tt>/bin/sh</tt> as its interpreter. If
5291 your script works with <prgn>ash</prgn>, it's probably
5292 POSIX compliant, but if you are in doubt, use
5293 <tt>/bin/bash</tt>.</p>
5296 Perl scripts should check for errors when making any
5297 system calls, including <tt>open</tt>, <tt>print</tt>,
5298 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5301 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5302 as scripting languages. See <em>Csh Programming
5303 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5304 FAQs. It can be found on
5305 <url id="http://language.perl.com/versus/csh.whynot">, or
5306 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5307 or even on <ftpsite>ftp.cpan.org</ftpsite>
5308 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5309 If an upstream package comes with <prgn>csh</prgn> scripts
5310 then you must make sure that they start with
5311 <tt>#!/bin/csh</tt> and make your package depend on the
5312 <prgn>c-shell</prgn> virtual package.</p>
5315 Any scripts which create files in world-writeable
5316 directories (e.g., in <tt>/tmp</tt>) must use a
5317 mechanism which will fail if a file with the same name
5321 The Debian base distribution provides the
5322 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5323 for use by scripts for this purpose.</p></sect>
5327 <heading>Symbolic links</heading>
5330 In general, symbolic links within a top-level directory
5331 should be relative, and symbolic links pointing from one
5332 top-level directory into another should be absolute. (A
5333 top-level directory is a sub-directory of the root
5337 In addition, symbolic links should be specified as short
5338 as possible, i.e., link targets like `foo/../bar' are
5342 Note that when creating a relative link using
5343 <prgn>ln</prgn> it is not necessary for the target of the
5344 link to exist relative to the working directory you're
5345 running <prgn>ln</prgn> from; nor is it necessary to
5346 change directory to the directory where the link is to be
5347 made. Simply include the string that should appear as the
5348 target of the link (this will be a pathname relative to
5349 the directory in which the link resides) as the first
5350 argument to <prgn>ln</prgn>.</p>
5353 For example, in your <prgn>Makefile</prgn> or
5354 <tt>debian/rules</tt>, do things like:
5356 ln -fs gcc $(prefix)/bin/cc
5357 ln -fs gcc debian/tmp/usr/bin/cc
5358 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5359 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5363 A symbolic link pointing to a compressed file should
5364 always have the same file extension as the referenced
5365 file. (For example, if a file `<tt>foo.gz</tt>' is
5366 referenced by a symbolic link, the filename of the link
5367 has to end with `<tt>.gz</tt>' too, as in
5368 `bar.gz.')</p></sect>
5372 <heading>Device files</heading>
5375 Packages must not include device files in the package file
5379 If a package needs any special device files that are not
5380 included in the base system, it must call
5381 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5382 after asking the user for permission to do so.</p>
5385 Packages must not remove any device files in the
5386 <tt>postrm</tt> or any other script. This is left to the
5387 system administrator.</p>
5390 Debian uses the serial devices
5391 <tt>/dev/ttyS*</tt>. Programs using the old
5392 <tt>/dev/cu*</tt> devices should be changed to use
5393 <tt>/dev/ttyS*</tt>.</p>
5396 <sect id="config files">
5397 <heading>Configuration files</heading>
5399 <heading>Definitions</heading>
5402 <tag>configuration file</tag>
5404 A file that affects the operation of program, or
5405 provides site- or host-specific information, or
5406 otherwise customizes the behavior of program.
5407 Typically, configuration files are intended to be
5408 modified by the system administrator (if needed or
5409 desired) to conform to local policy or provide more
5410 useful site-specific behavior.</p>
5413 <tag><tt>conffile</tt></tag>
5415 A file listed in a package's <tt>conffiles</tt>
5416 file, and is treated specially by <prgn>dpkg</prgn>
5417 (see the <em>Debian Packaging Manual</em>).</p>
5423 The distinction between these two is important; they are
5424 not interchangeable concepts. Almost all
5425 <tt>conffiles</tt> are configuration files, but many
5426 configuration files are not <tt>conffiles</tt>.</p>
5429 Note that a script that embeds configuration information
5430 (such as most of the files in <tt>/etc/init.d</tt> and
5431 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5432 configuration file and should be treated as such.</p>
5436 <heading>Location</heading>
5438 Any configuration files created or used by your package
5439 must reside in <tt>/etc</tt>. If there are several you
5440 should consider creating a subdirectory of <tt>/etc</tt>
5441 named after your package.</p>
5444 If your package creates or uses configuration files
5445 outside of <tt>/etc</tt>, and it is not feasible to modify
5446 the package to use the <tt>/etc</tt>, you should still put
5447 the files in <tt>/etc</tt> and create symbolic links to
5448 those files from the location that the package
5453 <heading>Behavior</heading>
5455 Configuration file handling must conform to the following
5459 <p>local changes must be preserved during a package
5463 <p>configuration files must be preserved when the
5464 package is removed, and only deleted when the
5465 package is purged.</p>
5470 The easy way to achieve this behavior is to make the
5471 configuration file a <tt>conffile</tt>. This is
5472 appropriate only if it is possible to distribute a default
5473 version that will work for most installations, although
5474 some system administrators may choose to modify it. This
5475 implies that the default version will be part of the
5476 package distribution, and must not be modified by the
5477 maintainer scripts during installation (or at any other
5482 In order to ensure that local changes are preserved
5483 correctly, no package may contain or make hard links to
5487 Rationale: There are two problems with hard links.
5488 The first is that some editors break the link while
5489 editing one of the files, so that the two files may
5490 unwittingly become different. The second is that
5491 <prgn>dpkg</prgn> might break the hard link while
5492 upgrading <tt>conffile</tt>s.
5498 The other way to do it is via the maintainer scripts.
5499 In this case, the configuration file must not be listed as
5500 a <tt>conffile</tt> and must not be part of the package
5501 distribution. If the existence of a file is required for
5502 the package to be sensibly configured it is the
5503 responsibility of the package maintainer to write scripts
5504 which correctly create, update, maintain and
5505 remove-on-purge the file. These scripts must be idempotent
5506 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5507 re-run them due to errors during installation or removal),
5508 must cope with all the variety of ways <prgn>dpkg</prgn>
5509 can call maintainer scripts, must not overwrite or
5510 otherwise mangle the user's configuration without asking,
5511 must not ask unnecessary questions (particularly during
5512 upgrades), and otherwise be good citizens.</p>
5515 The scripts are not required to configure every possible option for
5516 the package, but only those necessary to get the package
5517 running on a given system. Ideally the sysadmin should not
5518 have to do any configuration other than that done
5519 (semi-)automatically by the <tt>postinst</tt> script.</p>
5522 A common practice is to create a script called
5523 <tt><var>package</var>-configure</tt> and have the
5524 package's <tt>postinst</tt> call it if and only if the
5525 configuration file does not already exist. In certain
5526 cases it is useful for there to be an example or template
5527 file which the maintainer scripts use. Such files should
5528 be in <tt>/usr/share/<package></tt> or
5529 <tt>/usr/lib/<package></tt> with a symbolic link
5530 from <tt>/usr/share/doc/<package>/examples</tt>
5531 if they are examples, and should be
5532 perfectly ordinary <prgn>dpkg</prgn>-handled files
5533 (<em>not</em> <tt>conffiles</tt>).
5537 These two styles of configuration file handling must
5538 not be mixed, for that way lies madness:
5539 <prgn>dpkg</prgn> will ask about overwriting the file
5540 every time the package is upgraded.</p>
5545 <heading>Sharing configuration files</heading>
5547 Packages which specify the same file as
5548 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5553 The maintainer scripts must not alter the conffile of
5554 <em>any</em> package, including the one the scripts belong
5558 If two or more packages use the same configuration file
5559 and it is reasonable for both to be installed at the same
5560 time, one of these packages must be defined as
5561 <em>owner</em> of the configuration file, i.e., it will be
5562 the package to list that distributes the file and lists it
5563 as a <tt>conffile</tt>. Other packages that use the
5564 configuration file must depend on the owning package if
5565 they require the configuration file to operate. If the
5566 other package will use the configuration file if present,
5567 but is capable of operating without it, no dependency need
5571 If it is desirable for two or more related packages to
5572 share a configuration file <em>and</em> for all of the
5573 related packages to be able to modify that configuration
5574 file, then the following should be done:
5578 have one of the related packages (the "core"
5579 package) manage the configuration file with
5580 maintainer scripts as described in the previous
5584 the core package should also provide a program that
5585 the other packages may use to modify the
5586 configuration file.</p>
5590 the related packages must use the provided program
5591 to make any modifications to the configuration file.
5592 They should either depend on the core package to
5593 guarantee that the configuration modifier program is
5594 available or accept gracefully that they cannot
5595 modify the configuration file if it is not.</p>
5600 Sometimes it's appropriate to create a new package which
5601 provides the basic infrastructure for the other packages
5602 and which manages the shared configuration files. (Check
5603 out the <tt>sgml-base</tt> package as an example.)</p>
5607 <heading>User configuration files ("dotfiles")</heading>
5610 Files in <tt>/etc/skel</tt> will automatically be copied
5611 into new user accounts by <prgn>adduser</prgn>. They
5612 should not be referenced there by any program.</p>
5615 Therefore, if a program needs a dotfile to exist in
5616 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5617 should be installed in <tt>/etc/skel</tt> (and listed in
5618 conffiles, if it is not generated and modified dynamically
5619 by the package's installation scripts).</p>
5622 However, programs that require dotfiles in order to
5623 operate sensibly (dotfiles that they do not create
5624 themselves automatically, that is) are a bad thing, and
5625 programs should be configured by the Debian default
5626 installation as close to normal as possible.</p>
5629 Therefore, if a program in a Debian package needs to be
5630 configured in some way in order to operate sensibly that
5631 configuration should be done in a site-wide global
5632 configuration file elsewhere in <tt>/etc</tt>. Only if the
5633 program doesn't support a site-wide default configuration
5634 and the package maintainer doesn't have time to add it
5635 may a default per-user file be placed in
5636 <tt>/etc/skel</tt>.</p>
5639 <tt>/etc/skel</tt> should be as empty as we can make it.
5640 This is particularly true because there is no easy
5641 mechanism for ensuring that the appropriate dotfiles are
5642 copied into the accounts of existing users when a package
5648 <heading>Log files</heading>
5650 The traditional approach to log files has been to set up ad
5651 hoc log rotation schemes using simple shell scripts and
5652 cron. While this approach is highly customizable, it
5653 requires quite a lot of sysadmin work. Even though the
5654 original Debian system helped a little by automatically
5655 installing a system which can be used as a template, this
5656 was deemed not enough.
5660 A better scheme is to use logrotate, a GPL'd program
5661 developed by Red Hat, which centralizes log management. It
5662 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5663 and a directory where packages can drop logrotation info
5664 (<tt>/etc/logrotate.d</tt>).
5668 Log files should usually be named
5669 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5670 log files, or need a separate directory for permissions
5671 reasons (<tt>/var/log</tt> is writable only by
5672 <tt>root</tt>), you should usually create a directory named
5673 <tt>/var/log/<var>package</var></tt>.</p>
5676 Log files must be rotated occasionally so
5677 that they don't grow indefinitely; the best way to do this
5678 is to drop a script into the directory
5679 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5680 logrotate. Here is a good example for a logrotate config
5681 file (for more information see <manref name="logrotate"
5689 /etc/init.d/foo force-reload
5693 Which rotates all files under `/var/log/foo', saves 12
5694 compressed generations, and sends a HUP signal at the end of
5700 Log files should be removed when the package is
5701 purged (but not when it is only removed), by checking the
5702 argument to the <tt>postrm</tt> script (see the <em>Debian
5703 Packaging Manual</em> for details).</p>
5708 <heading>Permissions and owners</heading>
5711 The rules in this section are guidelines for general use.
5712 If necessary you may deviate from the details below.
5713 However, if you do so you must make sure that what is done
5714 is secure and you should try to be as consistent as possible
5715 with the rest of the system. You should probably also
5716 discuss it on <prgn>debian-devel</prgn> first.</p>
5719 Files should be owned by <tt>root.root</tt>, and made
5720 writable only by the owner and universally readable (and
5721 executable, if appropriate).</p>
5724 Directories should be mode 755 or (for group-writability)
5725 mode 2775. The ownership of the directory should be
5726 consistent with its mode--if a directory is mode 2775, it
5727 should be owned by the group that needs write access to
5731 Setuid and setgid executables should be mode 4755 or 2755
5732 respectively, and owned by the appropriate user or group.
5733 They should not be made unreadable (modes like 4711 or
5734 2711 or even 4111); doing so achieves no extra security,
5735 because anyone can find the binary in the freely available
5736 Debian package--it is merely inconvenient. For the same
5737 reason you should not restrict read or execute permissions
5738 on non-set-id executables.</p>
5741 Some setuid programs need to be restricted to particular
5742 sets of users, using file permissions. In this case they
5743 should be owned by the uid to which they are set-id, and
5744 by the group which should be allowed to execute them.
5745 They should have mode 4754; there is no point in making
5746 them unreadable to those users who must not be allowed to
5750 You must not arrange that the system administrator can only
5751 reconfigure the package to correspond to their local
5752 security policy by changing the permissions on a binary.
5753 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5754 to conffiles and other similar objects) have their
5755 permissions reset to the distributed permissions when the
5756 package is reinstalled. Instead you should consider (for
5757 example) creating a group for people allowed to use the
5758 program(s) and making any setuid executables executable
5759 only by that group.</p>
5762 If you need to create a new user or group for your package
5763 there are two possibilities. Firstly, you may need to
5764 make some files in the binary package be owned by this
5765 user or group, or you may need to compile the user or
5766 group id (rather than just the name) into the binary
5767 (though this latter should be avoided if possible, as in
5768 this case you need a statically allocated id).</p>
5771 If you need a statically allocated id, you must ask for a
5772 user or group id from the base system
5773 maintainer, and must not release the package until you
5774 have been allocated one. Once you have been allocated one
5775 you must make the package depend on a version of the base
5776 system with the id present in <tt>/etc/passwd</tt> or
5777 <tt>/etc/group</tt>, or alternatively arrange for your
5778 package to create the user or group itself with the
5779 correct id (using <tt>adduser</tt>) in its pre- or
5780 post-installation script (the latter is to be preferred if
5781 it is possible).</p>
5784 On the other hand, the program might be able to determine the
5785 uid or gid from the group name at runtime, so that a
5786 dynamic id can be used. In this case you should choose an
5787 appropriate user or group name, discussing this on
5788 <prgn>debian-devel</prgn> and checking with the base
5789 system maintainer that it is unique and that they do not
5790 wish you to use a statically allocated id instead. When
5791 this has been checked you must arrange for your package to
5792 create the user or group if necessary using
5793 <prgn>adduser</prgn> in the pre- or post-installation
5794 script (again, the latter is to be preferred if it is
5798 Note that changing the numeric value of an id associated with a name
5799 is very difficult, and involves searching the file system for all
5800 appropriate files. You need to think carefully whether a static or
5801 dynamic id is required, since changing your mind later will cause
5807 <heading>Customized programs</heading>
5809 <sect id="arch-spec">
5810 <heading>Architecture specification strings</heading>
5813 If a program needs to specify an <em>architecture specification
5814 string</em> in some place, the following format should be used:
5816 <arch>-<os>
5818 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5819 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5820 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5821 operating system.</p>
5823 Note, that we don't want to use `<arch>-debian-linux'
5824 to apply to the rule `architecture-vendor-os' since this
5825 would make our programs incompatible to other Linux
5826 distributions. Also note, that we don't use
5827 `<arch>-unknown-linux', since the `unknown' does not
5828 look very good.</p></sect>
5832 <heading>Daemons</heading>
5835 The configuration files <tt>/etc/services</tt>,
5836 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5837 by the <prgn>netbase</prgn> package and may not be modified
5838 by other packages.</p>
5841 If a package requires a new entry in one of these files, the
5842 maintainer should get in contact with the
5843 <prgn>netbase</prgn> maintainer, who will add the entries
5844 and release a new version of the <prgn>netbase</prgn>
5848 The configuration file <tt>/etc/inetd.conf</tt> must not be
5849 modified by the package's scripts except via the
5850 <prgn>update-inetd</prgn> script or the
5851 <prgn>DebianNet.pm</prgn> Perl module.</p>
5854 If a package wants to install an example entry into
5855 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5856 exactly one hash character (<tt>#</tt>). Such lines are
5857 treated as `commented out by user' by the
5858 <prgn>update-inetd</prgn> script and are not changed or
5859 activated during a package updates.</p></sect>
5863 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5866 Some programs need to create pseudo-ttys. This should be done
5867 using Unix98 ptys if the C library supports it. The resulting
5868 program must not be installed setuid root, unless that
5869 is required for other functionality.
5873 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5874 <tt>/var/log/lastlog</tt> must be installed writeable by
5875 group utmp. Programs who need to modify those files must
5876 be installed setgid utmp.
5881 <heading>Editors and pagers</heading>
5884 Some programs have the ability to launch an editor or pager
5885 program to edit or display a text document. Since there are
5886 lots of different editors and pagers available in the Debian
5887 distribution, the system administrator and each user should
5888 have the possibility to choose his/her preferred editor and
5892 In addition, every program should choose a good default
5893 editor/pager if none is selected by the user or system
5897 Thus, every program that launches an editor or pager must
5898 use the EDITOR or PAGER environment variables to determine
5899 the editor/pager the user wants to get started. If these
5900 variables are not set, the programs <tt>/usr/bin/editor</tt>
5901 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5904 These two files are managed through `alternatives.' That is,
5905 every package providing an editor or pager must call the
5906 <prgn>update-alternatives</prgn> script to register these
5910 If it is very hard to adapt a program to make us of the
5911 EDITOR and PAGER variables, that program may be configured
5912 to use <tt>/usr/bin/sensible-editor</tt> and
5913 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5914 respectively. These are two scripts provided in the Debian
5915 base system that check the EDITOR and PAGER variables and
5916 launch the appropriate program or fall back to
5917 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5921 A program may also use the VISUAL environment variable to
5922 determine the user's choice of editor. If it exists, it
5923 should take precedence over EDITOR. This is in fact what
5924 <tt>/usr/bin/sensible-editor</tt> does.</p>
5927 It is not required for a package to depend on
5928 `editor' and `pager', nor is it required for a package to
5929 provide such virtual packages.
5932 The Debian base system already provides an editor and
5941 <sect id="web-appl">
5942 <heading>Web servers and applications</heading>
5945 This section describes the locations and URLs that should
5946 be used by all web servers and web application in the Debian
5952 <p>Cgi-bin executable files are installed in the
5955 /usr/lib/cgi-bin/<cgi-bin-name>
5957 and should be referred to as
5959 http://localhost/cgi-bin/<cgi-bin-name>
5960 </example></p></item>
5963 <item><p>Access to html documents</p>
5966 Html documents for a package are stored in
5967 <tt>/usr/share/doc/<var>package</var></tt> but should
5968 be accessed via symlinks as
5969 <tt>/usr/doc/<var>package</var></tt><footnote> for
5970 backward compatibility, see <ref id="usrdoc"></footnote>
5971 and can be referred to as
5973 http://localhost/doc/<package>/<filename>
5974 </example></p></item>
5977 <item><p>Web Document Root</p>
5980 Web Applications should try to avoid storing files in
5981 the Web Document Root. Instead they should use the
5982 /usr/share/doc/<package> directory for documents and
5983 register the Web Application via the menu package. If
5984 access to the web-root is unavoidable then use
5988 as the Document Root. This might be just a
5989 symbolic link to the location where the sysadmin has
5990 put the real document root.</p>
5993 </enumlist></p></sect>
5997 <heading>Mail transport, delivery and user agents</heading>
6000 Debian packages which process electronic mail, whether
6001 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6002 must make sure that they are compatible with the
6003 configuration decisions below. Failure to do this may
6004 result in lost mail, broken <tt>From:</tt> lines, and other
6005 serious brain damage!</p>
6008 The mail spool is <tt>/var/spool/mail</tt> and the interface
6009 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6010 per the FHS). The mail spool is part of the base system
6011 and not part of the MTA package.</p>
6014 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6015 programs (like IMAP daemons) must lock the mailbox in an
6016 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6017 be combined with dot locking. To avoid deadlocks, a
6018 program should use <tt>fcntl()</tt> first and dot locking
6019 after this or alternatively implement the two locking
6020 methods in a non blocking way<footnote>
6022 If it is not possible to establish both locks, the
6023 system shouldn't wait for the second lock to be
6024 established, but remove the first lock, wait a (random)
6025 time, and start over locking again.</p>
6026 </footnote>. Using the functions <tt>maillock</tt> and
6027 <tt>mailunlock</tt> provided by the
6028 <tt>liblockfile*</tt><footnote>
6030 <tt>liblockfile</tt> version >>1.01</p>
6031 </footnote> packages is the recommended way to realize this.
6035 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6036 unless the user has chosen otherwise. A MUA may remove a
6037 mailbox (unless it has nonstandard permissions) in which
6038 case the MTA or another MUA must recreate it if needed.
6039 Mailboxes must be writable by group mail.</p>
6042 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6043 be setgid mail to do the locking mentioned above (and
6044 must obviously avoid accessing other users' mailboxes
6045 using this privilege).</p>
6048 <tt>/etc/aliases</tt> is the source file for the system mail
6049 aliases (e.g., postmaster, usenet, etc.)--it is the one
6050 which the sysadmin and <tt>postinst</tt> scripts may edit.
6051 After <tt>/etc/aliases</tt> is edited the program or human
6052 editing it must call <prgn>newaliases</prgn>. All MTA
6053 packages must come with a <prgn>newaliases</prgn> program,
6054 even if it does nothing, but older MTA packages do not do
6055 this so programs should not fail if <prgn>newaliases</prgn>
6056 cannot be found.</p>
6059 The convention of writing <tt>forward to
6060 <var>address</var></tt> in the mailbox itself is not
6061 supported. Use a <tt>.forward</tt> file instead.</p>
6064 The <prgn>rmail</prgn> program used by UUCP
6065 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6066 Likewise, <prgn>rsmtp</prgn>, for receiving
6067 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6071 If you need to know what name to use (for example) on
6072 outgoing news and mail messages which are generated locally,
6073 you should use the file <tt>/etc/mailname</tt>. It will
6074 contain the portion after the username and <tt>@</tt> (at)
6075 sign for email addresses of users on the machine (followed
6079 A package should check for the existence of this file. If
6080 it exists it should use it without comment. (An MTA's
6081 prompting configuration script may wish to prompt the user
6082 even if it finds this file exists.) If it does not exist it
6083 should prompt the user for the value and store it in
6084 <tt>/etc/mailname</tt> as well as using it in the package's
6085 configuration. The prompt should make it clear that the
6086 name will not just be used by that package. For example, in
6087 this situation the INN package says:
6089 Please enter the `mail name' of your system. This is the
6090 hostname portion of the address to be shown on outgoing
6091 news and mail messages. The default is
6092 <var>syshostname</var>, your system's host name. Mail
6093 name [`<var>syshostname</var>']:
6095 where <var>syshostname</var> is the output of <tt>hostname
6096 --fqdn</tt>.</p></sect>
6100 <heading>News system configuration</heading>
6103 All the configuration files related to the NNTP (news)
6104 servers and clients should be located under
6105 <tt>/etc/news</tt>.</p>
6108 There are some configuration issues that apply to a number
6109 of news clients and server packages on the machine. These
6113 <tag>/etc/news/organization</tag>
6114 <item><p>A string which should appear as the
6115 organization header for all messages posted
6116 by NNTP clients on the machine</p></item>
6118 <tag>/etc/news/server</tag>
6119 <item><p>Contains the FQDN of the upstream NNTP
6120 server, or localhost if the local machine is
6121 an NNTP server.</p></item>
6124 Other global files may be added as required for cross-package news
6125 configuration.</p></sect>
6129 <heading>Programs for the X Window System</heading>
6132 <em>Programs that may be configured with support for the X Window
6133 System</em> must be configured to do so and must declare any
6134 package dependencies necessary to satisfy their runtime
6135 requirements when using the X Window System, unless the package
6136 in question is of standard or higher priority, in which case
6137 X-specific binaries may be split into a separate package, or
6138 alternative versions of the package with X support may be
6144 <em>Packages which provide an X server</em> that, directly or
6145 indirectly, communicates with real input and display hardware
6146 should declare in their control data that they provide the
6147 virtual package <tt>xserver</tt>.
6150 This implements current practice, and provides an actual
6151 policy for usage of the "xserver" virtual package which
6152 appears in the virtual packages list. In a nutshell, X
6153 servers that interface directly with the display and input
6154 hardware or via another subsystem (e.g., GGI) should provide
6155 xserver. Things like Xvfb, Xnest, and Xprt should not.
6161 <em>Packages that provide a terminal emulator</em> for the X
6162 Window System which support a terminal type with a terminfo
6163 description provided in the <tt>ncurses-base</tt> package
6164 should declare in their control data that they provide the
6165 virtual package <tt>x-terminal-emulator</tt>. They should
6166 also register themselves as an alternative for
6167 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6172 <em>Packages that provide window managers</em> should declare in
6173 their control data that they provide the virtual package
6174 <tt>x-window-manager</tt>. They should also register themselves as an
6175 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6176 calculated as follows:
6178 <item>Start with a priority of 20.</item>
6179 <item>If the window manager supports the Debian menu system,
6180 add 20 points if this support is available in the
6181 package's default configuration (i.e., no
6182 configuration files belonging to the system or user
6183 have to be edited to activate the feature); if
6184 configuration files must be modified, add only 10
6186 <item>If the window manager permits the X session to be
6187 restarted using a <em>different</em> window manager
6188 (without killing the X server) in its default
6189 configuration, add 10 points; otherwise add
6195 <em>Packages that provide fonts for the X Window System</em>
6196 must do a number of things to ensure that they are both
6197 available without modification of the X or font server
6198 configuration, and that they do not corrupt files used by
6199 other font packages to register information about themselves.
6202 Fonts of any type supported by the X Window System
6203 should be be in a separate binary package from any
6204 executables, libraries, or documentation (except that
6205 specific to the fonts shipped); if a program or
6206 library is <em>unusable</em> without one or more
6207 specific fonts, the package containing the program or
6208 library should declare a dependency on the package(s)
6209 containing the font(s) it requires.
6212 BDF fonts should be converted to PCF fonts with the
6213 <tt>bdftopcf</tt> utility (available in the
6214 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6215 placed in a directory that corresponds to their
6219 100 dpi fonts should be placed in
6220 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6223 75 dpi fonts should be placed in
6224 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6227 Character-cell fonts, cursor fonts, and other
6228 low-resolution fonts should be placed in
6229 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6234 Speedo fonts should be placed in
6235 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6238 Type 1 fonts should be placed in
6239 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6240 metric files are available, they may be placed here as
6244 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6245 other than those listed above should be neither created nor
6246 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6247 excepted for historical reasons, but installation of files into
6248 these directories remains discouraged.)
6251 Font packages may, instead of placing files directly in
6252 the X font directories listed above, provide symbolic links in
6253 the font directory which point to the files' actual location
6254 in the filesystem. Such a location should comply with the
6258 Font packages should not contain both 75dpi and 100dpi
6259 versions of a font. If both are available, they should be
6260 provided in separate binary packages with "-75dpi" or "-100dpi"
6261 appended to the names of the packages containing the
6262 corresponding fonts.
6265 Fonts destined for the <tt>misc</tt> subdirectory should
6266 not be included in the same package as 75dpi or 100dpi fonts;
6267 instead, they should be provided in a separate package with
6268 "-misc" appended to its name.
6271 Font packages <em>must not</em> provide the files
6272 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6273 <tt>fonts.scale</tt> in a font directory.
6276 <tt>fonts.dir</tt> files must not be provided at
6280 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6281 files, if needed, should be provided in the
6283 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6284 where <em>fontdir</em> is the name of the
6286 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6287 package's corresponding fonts are stored (e.g.,
6288 <tt>75dpi</tt> or <tt>misc</tt>),
6289 <em>package</em> is the name of the package that
6290 provides these fonts, and <em>extension</em> is
6291 either <tt>scale</tt> or <tt>alias</tt>,
6292 whichever corresponds to the file
6298 Font packages must declare a dependency on
6299 <tt>xutils</tt> and, in the package
6300 post-installation and post-removal scripts, invoke the
6301 <tt>mkfontdir</tt> command on each directory into
6302 which they installed fonts.
6305 Font packages that provide one or more
6306 <tt>fonts.scale</tt> files as described above must declare a
6307 versioned dependency on <tt>xutils (>=
6308 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6309 directory into which they installed fonts
6310 <em>before</em> invoking <tt>mkfontdir</tt> on that
6311 directory. This invocation must occur in both the
6312 post-installation and post-removal scripts.
6315 Font packages that provide one or more
6316 <tt>fonts.alias</tt> files as described above must
6317 declare a versioned dependency on <tt>xutils
6318 (>= 4.0.2)</tt> and, in the package
6319 post-installation and post-removal scripts, invoke
6320 <tt>update-fonts-alias</tt> on each directory into
6321 which they installed fonts.
6324 Font packages must not provide alias names for the
6325 fonts they include which collide with alias names already in
6326 use by fonts already packaged.
6329 Font packages must not provide fonts with the same XLFD
6330 registry name as another font already packaged.
6336 <em>Application defaults</em> files must be installed in the
6337 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6338 localized subdirectory of <tt>/etc/X11/</tt> as described in
6339 the <em>X Toolkit Intrinsics - C Language Interface</em>
6340 manual is also permitted). They must be registered as
6341 <em>conffile</em>s or handled as configuration files. For
6342 programs that are not linked against the X Toolkit (Xt)
6343 library, customization of programs' X resources may also be
6344 supported with the provision of a file with the same name as
6345 that of the package placed in the
6346 <tt>/etc/X11/Xresources/</tt> directory, which must
6347 registered as a <em>conffile</em> or handled as a
6348 configuration file. <em>Important:</em> packages that
6349 install files into the <tt>/etc/X11/Xresources/</tt>
6350 directory <em>must</em> declare a conflict with <tt>xbase
6351 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6352 possible for the installing package to destroy a
6353 previously-existing <tt>/etc/X11/Xresources</tt> file which
6354 had been customized by the system administrator.
6358 <em>Packages using the X Window System should abide by the FHS
6359 standard whenever possible</em>; they should install binaries,
6360 libraries, manual pages, and other files in FHS-mandated
6361 locations wherever possible. This means that files must
6362 not be installed into <tt>/usr/X11R6/bin/</tt>,
6363 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6364 this is necessary for the package to operate properly.
6365 Configuration files for window managers and display managers
6366 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6367 corresponding to the package name due to these programs'
6368 tight integration with the mechanisms of the X Window
6369 System. Application-level programs should use the
6370 <tt>/etc/</tt> directory unless otherwise mandated by
6371 policy. The installation of files into subdirectories of
6372 <tt>/usr/X11R6/include/X11/</tt> and
6373 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6374 package maintainers should determine if subdirectories of
6375 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6376 instead (symlinks from the X11R6 directories to
6377 FHS-compliant locations is encouraged if the program is not
6378 easily configured to look elsewhere for its files).
6379 Packages must not provide -- or install files into -- the
6380 directories <tt>/usr/bin/X11/</tt>,
6381 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6382 Files within a package should, however, make reference to
6383 these directories, rather than their X11R6-named
6384 counterparts <tt>/usr/X11R6/bin/</tt>,
6385 <tt>/usr/X11R6/include/X11/</tt>, and
6386 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6387 referred to have not been moved to FHS-compliant locations.
6391 <em>Programs that require the non-DFSG-compliant OSF/Motif
6392 library</em> should be compiled against and tested with
6393 LessTif (a free re-implementation of Motif) instead. If the
6394 maintainer judges that the program or programs do not work
6395 sufficiently well with LessTif to be distributed and
6396 supported, but do so when compiled against Motif, then two
6397 versions of the package should be created; one linked
6398 statically against Motif and with <tt>-smotif</tt> appended
6399 to the package name, and one linked dynamically against
6400 Motif and with <tt>-dmotif</tt> appended to the package
6401 name. Both Motif-linked versions are dependent upon
6402 non-DFSG-compliant software and thus cannot be uploaded to
6403 the main distribution; if the software is itself
6404 DFSG-compliant it may be uploaded to the contrib
6405 distribution. While known existing versions of OSF/Motif
6406 permit unlimited redistribution of binaries linked against
6407 the library (whether statically or dynamically), it is the
6408 package maintainer's responsibility to determine whether
6409 this is permitted by the license of the copy of OSF/Motif in
6410 his or her possession.
6416 <heading>Emacs lisp programs</heading>
6419 Please refer to the `Debian Emacs Policy' (documented in
6420 <tt>debian-emacs-policy.gz</tt> of the
6421 <prgn>emacsen-common</prgn> package) for details of how to
6422 package emacs lisp programs.</p></sect>
6426 <heading>Games</heading>
6429 The permissions on /var/games are 755
6430 <tt>root.root</tt>.</p>
6433 Each game decides on its own security policy.</p>
6436 Games which require protected, privileged access to
6437 high-score files, savegames, etc., may be made
6438 set-<em>group</em>-id (mode 2755) and owned by
6439 <tt>root.games</tt>, and use files and directories with
6440 appropriate permissions (770 <tt>root.games</tt>, for
6441 example). They must not be made
6442 set-<em>user</em>-id, as this causes security problems. (If
6443 an attacker can subvert any set-user-id game they can
6444 overwrite the executable of any other, causing other players
6445 of these games to run a Trojan horse program. With a
6446 set-group-id game the attacker only gets access to less
6447 important game data, and if they can get at the other
6448 players' accounts at all it will take considerably more
6452 Some packages, for example some fortune cookie programs, are
6453 configured by the upstream authors to install with their
6454 data files or other static information made unreadable so
6455 that they can only be accessed through set-id programs
6456 provided. You should not do this in a Debian package: anyone can
6457 download the <tt>.deb</tt> file and read the data from it,
6458 so there is no point making the files unreadable. Not
6459 making the files unreadable also means that you don't have
6460 to make so many programs set-id, which reduces the risk of a
6464 As described in the FHS, binaries of games should be
6465 installed in the directory <tt>/usr/games</tt>. This also
6466 applies to games that use the X Window System. Manual pages
6467 for games (X and non-X games) should be installed in
6468 <tt>/usr/share/man/man6</tt>.</p>
6472 <chapt><heading>Documentation</heading>
6476 <heading>Manual pages</heading>
6479 You should install manual pages in <prgn>nroff</prgn> source
6480 form, in appropriate places under <tt>/usr/share/man</tt>. You
6481 should only use sections 1 to 9 (see the FHS for more
6482 details). You must not install a preformatted `cat
6486 Each program, utility, and function should have an
6487 associated manpage included in the same package. It is
6488 suggested that all configuration files also have a manual
6489 page included as well.
6493 If no manual page is available for a particular program,
6494 utility, function or configuration file and this is reported as a bug on
6495 debian-bugs, a symbolic link from the requested manual page
6496 to the <manref name="undocumented" section="7"> manual page
6497 may be provided. This symbolic link can be created from
6498 <tt>debian/rules</tt> like this:
6500 ln -s ../man7/undocumented.7.gz \
6501 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6503 This manpage claims that the lack of a manpage has been
6504 reported as a bug, so you may only do this if it really has
6505 (you can report it yourself, if you like). Do not close the
6506 bug report until a proper manpage is available.</p>
6509 You may forward a complaint about a missing manpage to the
6510 upstream authors, and mark the bug as forwarded in the
6511 Debian bug tracking system. Even though the GNU Project do
6512 not in general consider the lack of a manpage to be a bug,
6513 we do--if they tell you that they don't consider it a bug
6514 you should leave the bug in our bug tracking system open
6518 Manual pages should be installed compressed using <tt>gzip
6522 If one manpage needs to be accessible via several names it
6523 is better to use a symbolic link than the <tt>.so</tt>
6524 feature, but there is no need to fiddle with the relevant
6525 parts of the upstream source to change from <tt>.so</tt> to
6526 symlinks--don't do it unless it's easy. You should not create hard
6527 links in the manual page directories, nor put
6528 absolute filenames in <tt>.so</tt> directives. The filename
6529 in a <tt>.so</tt> in a manpage should be relative to the
6530 base of the manpage tree (usually
6531 <tt>/usr/share/man</tt>).</p></sect>
6535 <heading>Info documents</heading>
6538 Info documents should be installed in <tt>/usr/share/info</tt>.
6539 They should be compressed with <tt>gzip -9</tt>.</p>
6542 Your package should call <prgn>install-info</prgn> to update the Info
6544 file, in its post-installation script:
6546 install-info --quiet --section Development Development \
6547 /usr/share/info/foobar.info
6551 It is a good idea to specify a section for the location of
6552 your program; this is done with the <tt>--section</tt>
6553 switch. To determine which section to use, you should look
6554 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6555 relevant (or create a new section if none of the current
6556 sections are relevant). Note that the <tt>--section</tt>
6557 flag takes two arguments; the first is a regular expression
6558 to match (case-insensitively) against an existing section,
6559 the second is used when creating a new one.</p>
6562 You should remove the entries in the pre-removal script:
6564 install-info --quiet --remove /usr/share/info/foobar.info
6568 If <prgn>install-info</prgn> cannot find a description entry
6569 in the Info file you must supply one. See <manref
6570 name="install-info" section="8"> for details.</p>
6574 <heading>Additional documentation</heading>
6577 Any additional documentation that comes with the package may
6578 be installed at the discretion of the package maintainer.
6579 Text documentation should be installed in a directory
6580 <tt>/usr/share/doc/<var>package</var></tt>, where
6581 <var>package</var> is the name of the package, and
6582 compressed with <tt>gzip -9</tt> unless it is small.</p>
6585 If a package comes with large amounts of documentation which
6586 many users of the package will not require you should create
6587 a separate binary package to contain it, so that it does not
6588 take up disk space on the machines of users who do not need
6589 or want it installed.</p>
6592 It is often a good idea to put text information files
6593 (<tt>README</tt>s, changelogs, and so forth) that come with
6594 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6595 in the binary package. However, you don't need to install
6596 the instructions for building and installing the package, of
6600 Files in <tt>/usr/share/doc</tt> should not be referenced by
6601 any program, and the system administrator should be able to
6602 delete them without causing any programs to break. Any files
6603 that are referenced by programs but are also useful as
6604 standalone documentation should be installed under
6605 <tt>/usr/share/<package>/</tt> and symlinked in
6606 <tt>/usr/share/doc/<package>/</tt>.
6612 <heading>Accessing the documentation</heading>
6615 Former Debian releases placed all additional documentation
6616 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6618 <tt>/usr/share/doc/<var>package</var></tt>, each package
6619 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6620 that points to the new location of its documentation in
6621 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6622 symlinks will be removed in the future, but they have to be
6623 there for compatibility reasons until all packages have
6624 moved and the policy is changed accordingly.</footnote>.
6625 The symlink must be created when the package is installed;
6626 it cannot be contained in the package itself due to problems
6627 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6628 this is to put the following in the package's
6629 <prgn>postinst</prgn>:
6631 if [ "$1" = "configure" ]; then
6632 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6633 -a -d /usr/share/doc/#PACKAGE# ]; then
6634 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6638 And the following in the package's <prgn>prerm</prgn>:
6640 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6641 -a -L /usr/doc/#PACKAGE# ]; then
6642 rm -f /usr/doc/#PACKAGE#
6649 <heading>Preferred documentation formats</heading>
6652 The unification of Debian documentation is being carried out
6656 If your package comes with extensive documentation in a
6657 mark up format that can be converted to various other formats
6658 you should if possible ship HTML versions in a binary
6659 package, in the directory
6660 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6663 <p>The rationale: The important thing here is that HTML
6664 docs should be available in <em>some</em> package, not
6665 necessarily in the main binary package, though. </p>
6670 Other formats such as PostScript may be provided at your
6674 <sect id="copyrightfile">
6675 <heading>Copyright information</heading>
6678 Every package must be accompanied by a verbatim copy of its
6679 copyright and distribution license in the file
6680 /usr/share/doc/<package-name>/copyright. This file must
6681 neither be compressed nor be a symbolic link.</p>
6684 In addition, the copyright file must say where the upstream
6685 sources (if any) were obtained, and should explain briefly what
6686 modifications were made in the Debian version of the package
6687 compared to the upstream one. It should name the original
6688 authors of the package and the Debian maintainer(s) who were
6689 involved with its creation.</p>
6692 A copy of the file which will be installed in
6693 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6694 in <tt>debian/copyright</tt>.</p>
6698 /usr/share/doc/<package-name> may be a symbolic link to a
6699 directory in /usr/share/doc only if two packages both come from
6700 the same source and the first package has a "Depends"
6701 relationship on the second. These rules are important
6702 because copyrights must be extractable by mechanical
6706 Packages distributed under the UCB BSD license, the Artistic
6707 license, the GNU GPL, and the GNU LGPL should refer to the
6708 files /usr/share/common-licenses/BSD,
6709 /usr/share/common-licenses/Artistic,
6710 /usr/share/common-licenses/GPL, and
6711 /usr/share/common-licenses/LGPL.
6714 Why "licenses" and not "copyright"? Because
6715 <tt>/usr/doc/copyright</tt> used to contain all the
6716 copyright files, plus the four common licenses GPL,
6717 LGPL, Artistic and BSD. Now individual copyright files
6718 for packages are no longer in a common directory. Once
6719 <tt>/usr/doc/copyright</tt> is almost empty it makes
6720 sense to rename "copyright" to "licenses"
6723 Why "common-licenses" and not "licenses"? Because if I
6724 put just "licenses" I'm sure I will receive a bug report
6725 saying "license foo is not included in the licenses
6726 directory. They are not all the licenses, just a few
6727 common ones. I could use /usr/share/doc/common-licenses
6728 but I think this is too long, and, after all, the GPL
6729 does not "document" anything, it is merely a license.
6735 You should not use the copyright file as a general <tt>README</tt>
6736 file. If your package has such a file it should be
6737 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6738 <tt>README.Debian</tt> or some other appropriate place.</p>
6742 <heading>Examples</heading>
6745 Any examples (configurations, source files, whatever),
6746 should be installed in a directory
6747 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6748 files should not be referenced by any program--they're there
6749 for the benefit of the system administrator and users, as
6750 documentation only. Architecture-specific example files
6751 should be installed in a directory
6752 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6753 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6754 to files in it. Or the latter directory may be a symlink to
6758 <sect id="instchangelog">
6759 <heading>Changelog files</heading>
6762 Packages that are not Debian-native must contain a copy of
6763 <tt>debian/changelog</tt> file from the Debian source tree
6764 in <tt>/usr/share/doc/<var>package</var></tt> as
6765 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6766 available, it should be accessible as
6767 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6768 plain text. If the upstream changelog is distributed in
6769 HTML, it should be made available in that form as
6770 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6771 and the <tt>changelog.gz</tt> should be generated using, eg,
6772 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6773 do not already conform to this naming convention, then this
6774 may be achieved either by renaming the files, or adding a
6775 symbolic link, at the maintainer's discretion.
6778 Rationale: People should not have to look into two
6779 places for upstream changelogs merely because they are
6787 All these files should be installed compressed using <tt>gzip -9</tt>,
6788 as they will become large with time even if they start out
6793 If the package has only one changelog which is used both as
6794 the Debian changelog and the upstream one because there is
6795 no separate upstream maintainer then that changelog should
6796 usually be installed as
6797 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6798 there is a separate upstream maintainer, but no upstream
6799 changelog, then the Debian changelog should still be called
6800 <tt>changelog.Debian.gz</tt>.</p>