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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/<em><package-name></em>/copyright</tt>
582 (see <ref id="copyrightfile"> for further details).
585 We reserve the right to restrict files from being included
586 anywhere in our archives if
587 <list compact="compact">
590 their use or distribution would break a law,
595 there is an ethical conflict in their distribution or
601 we would have to sign a license for them, or
606 their distribution would conflict with other project
614 Programs whose authors encourage the user to make
615 donations are fine for the main distribution, provided
616 that the authors do not claim that not donating is
617 immoral, unethical, illegal or something similar; in such
618 a case they must go in <em>non-free</em>.</p>
621 Packages whose copyright permission notices (or patent
622 problems) do not even allow redistribution of binaries
623 only, and where no special permission has been obtained,
624 must not be placed on the Debian FTP site and its mirrors
628 Note that under international copyright law (this applies
629 in the United States, too), <em>no</em> distribution or
630 modification of a work is allowed without an explicit
631 notice saying so. Therefore a program without a copyright
632 notice <em>is</em> copyrighted and you may not do anything
633 to it without risking being sued! Likewise if a program
634 has a copyright notice but no statement saying what is
635 permitted then nothing is permitted.</p>
638 Many authors are unaware of the problems that restrictive
639 copyrights (or lack of copyright notices) can cause for
640 the users of their supposedly-free software. It is often
641 worthwhile contacting such authors diplomatically to ask
642 them to modify their license terms. However, this can be a
643 politically difficult thing to do and you should ask for
644 advice on the <tt>debian-legal</tt> mailing list first, as
649 When in doubt about a copyright, send mail to
650 <email>debian-legal@lists.debian.org</email>. Be prepared
651 to provide us with the copyright statement. Software
652 covered by the GPL, public domain software and BSD-like
653 copyrights are safe; be wary of the phrases `commercial
654 use prohibited' and `distribution restricted'.
658 <heading>Subsections</heading>
661 The packages in the sections <em>main</em>,
662 <em>contrib</em> and <em>non-free</em> are grouped further
663 into <em>subsections</em> to simplify handling.
667 The section and subsection for each package should be
668 specified in the package's <tt>Section</tt> control
669 record. However, the maintainer of the Debian archive
670 may override this selection to ensure the consistency of
671 the Debian distribution. The <tt>Section</tt> field
672 should be of the form:
673 <list compact="compact">
676 <em>subsection</em> if the package is in the
677 <em>main</em> section,
682 <em>section/subsection</em> if the package is in
683 the <em>contrib</em> or <em>non-free</em> section,
689 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
690 <tt>non-US/non-free</tt> if the package is in
691 <em>non-US/main</em>, <em>non-US/contrib</em> or
692 <em>non-US/non-free</em> respectively.
699 The Debian archive maintainers provide the authoritative
700 list of subsections. At present, they are:
701 <em>admin</em>, <em>base</em>, <em>comm</em>,
702 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
703 <em>editors</em>, <em>electronics</em>, <em>games</em>,
704 <em>graphics</em>, <em>hamradio</em>,
705 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
706 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
707 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
708 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
709 <em>sound</em>, <em>tex</em>, <em>text</em>,
710 <em>utils</em>, <em>web</em>, <em>x11</em>.
714 <heading>Priorities</heading>
717 Each package should have a <em>priority</em> value, which is
718 included in the package's <em>control record</em>. This
719 information is used by the Debian package management tools
720 to separate high-priority packages from less-important
724 The following <em>priority levels</em> are recognised by the
725 Debian package management tools.
727 <tag><tt>required</tt></tag>
730 Packages which are necessary for the proper
731 functioning of the system. You must not remove these
732 packages or your system may become totally broken and
733 you may not even be able to use <prgn>dpkg</prgn> to
734 put things back. Systems with only the
735 <tt>required</tt> packages are probably unusable, but
736 they do have enough functionality to allow the
737 sysadmin to boot and install more software.</p>
739 <tag><tt>important</tt></tag>
742 Important programs, including those which one would
743 expect to find on any Unix-like system. If the
744 expectation is that an experienced Unix person who
745 found it missing would say `What on earth is going on,
746 where is <prgn>foo</prgn>?', it must be an
747 <tt>important</tt> package.
750 This is an important criterion because we are
751 trying to produce, amongst other things, a free
755 Other packages without which the system will not run
756 well or be usable must also have priority
757 <tt>important</tt>. This does
758 <em>not</em> include Emacs, the X Window System, TeX
759 or any other large applications. The
760 <tt>important</tt> packages are just a bare minimum of
761 commonly-expected and necessary tools.</p>
763 <tag><tt>standard</tt></tag>
766 These packages provide a reasonably small but not too
767 limited character-mode system. This is what will
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>
1186 <sect id="standardsversion">
1189 In the source package's <tt>Standards-Version</tt> control
1190 field, you must specify the most recent version number of
1191 this policy document with which your package complies.
1192 The current version number is &version;.
1196 This information may be used to file bug reports
1197 automatically if your package becomes too much out of
1202 The version number has four components--major and minor
1203 version number and major and minor patch level. When the
1204 standards change in a way that requires every package to
1205 change the major number will be changed. Significant
1206 changes that will require work in many packages will be
1207 signaled by a change to the minor number. The major patch
1208 level will be changed for any change to the meaning of the
1209 standards, however small; the minor patch level will be
1210 changed when only cosmetic, typographical or other edits
1211 are made which neither change the meaning of the document
1212 nor affect the contents of packages.</p>
1215 Thus only the first three components of the policy version
1216 are significant in the <em>Standards-Version</em> control
1217 field, and so either these three components or the all
1218 four components may be specified.
1221 In the past, people specified the full version number
1222 in the Standards-Version field, for example `2.3.0.0'.
1223 Since minor patch-level changes don't introduce new
1224 policy, it was thought it would be better to relax
1225 policy and only require the first 3 components to be
1226 specified, in this example `2.3.0'. All four
1227 components may still be used if someone wishes to do
1234 You should regularly, and especially if your package has
1235 become out of date, check for the newest Policy Manual
1236 available and update your package, if necessary. When your
1237 package complies with the new standards you should update the
1238 <tt>Standards-Version</tt> source package field and
1242 See the file <tt>upgrading-checklist</tt> for
1243 information about policy which has changed between
1244 different versions of this document.
1252 <heading>Package relationships</heading>
1255 Source packages should specify which binary packages they
1256 require to be installed or not to be installed in order to
1257 build correctly. For example, if building a package
1258 requires a certain compiler, then the compiler should be
1259 specified as a build-time dependency.
1263 It is not necessary to explicitly specify build-time
1264 relationships on a minimal set of packages that are always
1265 needed to compile, link and put in a Debian package a
1266 standard "Hello World!" program written in C or C++. The
1267 required packages are called <em>build-essential</em>, and
1268 an informational list can be found in
1269 <tt>/usr/share/doc/build-essential/list</tt> (which is
1270 contained in the <tt>build-essential</tt>
1276 <p>This allows maintaining the list separately
1277 from the policy documents (the list does not
1278 need the kind of control that the policy
1284 Having a separate package allows one to install
1285 the build-essential packages on a machine, as
1286 well as allowing other packages such as task
1287 packages to require installation of the
1288 build-essential packages using the depends
1294 The separate package allows bug reports against
1295 the list to be categorized separately from
1296 the policy management process in the BTS.
1306 When specifying the set of build-time dependencies, one
1307 should list only those packages explicitly required by the
1308 build. It is not necessary to list packages which are
1309 required merely because some other package in the list of
1310 build-time dependencies depends on them.
1313 The reason for this is that dependencies change, and
1314 you should list all those packages, and <em>only</em>
1315 those packages that <em>you</em> need directly. What
1316 others need is their business. For example, if you
1317 only link against <tt>libimlib</tt>, you will need to
1318 build-depend on <package>libimlib2-dev</package> but
1319 not against any <tt>libjpeg*</tt> packages, even
1320 though <tt>libimlib2-dev</tt> currently depends on
1321 them: installation of <package>libimlib2-dev</package>
1322 will automatically ensure that all of its run-time
1323 dependencies are satisfied.
1329 If build-time dependencies are specified, it must be
1330 possible to build the package and produce working binaries
1331 on a system with only essential and build-essential
1332 packages installed and also those required to satisfy the
1333 build-time relationships (including any implied
1334 relationships). In particular, this means that version
1335 clauses should be used rigorously in build-time
1336 relationships so that one cannot produce bad or
1337 inconsistently configured packages when the relationships
1338 are properly satisfied.
1342 <heading>Changes to the upstream sources</heading>
1345 If changes to the source code are made that are not
1346 specific to the needs of the Debian system, they should be
1347 sent to the upstream authors in whatever form they prefer
1348 so as to be included in the upstream version of the
1352 If you need to configure the package differently for
1353 Debian or for Linux, and the upstream source doesn't
1354 provide a way to do so, you should add such configuration
1355 facilities (for example, a new <prgn>autoconf</prgn> test
1356 or <tt>#define</tt>) and send the patch to the upstream
1357 authors, with the default set to the way they originally
1358 had it. You can then easily override the default in your
1359 <tt>debian/rules</tt> or wherever is appropriate.</p>
1362 You should make sure that the <prgn>configure</prgn> utility
1363 detects the correct architecture specification string
1364 (refer to <ref id="arch-spec"> for details).</p>
1367 If you need to edit a <prgn>Makefile</prgn> where
1368 GNU-style <prgn>configure</prgn> scripts are used, you
1369 should edit the <tt>.in</tt> files rather than editing the
1370 <prgn>Makefile</prgn> directly. This allows the user to
1371 reconfigure the package if necessary. You should
1372 <em>not</em> configure the package and edit the generated
1373 <prgn>Makefile</prgn>! This makes it impossible for
1374 someone else to later reconfigure the package.</p></sect1>
1378 <heading>Documenting your changes</heading>
1381 You should document your changes and updates to the source
1382 package properly in the <tt>debian/changelog</tt> file. (Note
1383 that mistakes in changelogs are usually best rectified by
1384 making a new changelog entry rather than "rewriting history"
1385 by editing old changelog entries.)</p>
1388 In non-experimental packages you must use a format for
1389 <tt>debian/changelog</tt> which is supported by the most
1390 recent released version of <prgn>dpkg</prgn>.
1393 If you wish to use an alternative format, you may do
1394 so as long as you include a parser for it in your
1395 source package. The parser must have an API
1396 compatible with that expected by
1397 <prgn>dpkg-genchanges</prgn> and
1398 <prgn>dpkg-gencontrol</prgn>. If there is general
1399 interest in the new format, you should contact the
1400 <package>dpkg</package> maintainer to have the parser
1401 script for it included in the <prgn>dpkg</prgn>
1402 package. (You will need to agree that the parser and
1403 its manpage may be distributed under the GNU GPL, just
1404 as the rest of `dpkg' is.)
1412 <heading>Error trapping in makefiles</heading>
1415 When <prgn>make</prgn> invokes a command in a makefile
1416 (including your package's upstream makefiles and
1417 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1418 means that <tt>sh</tt>'s usual bad error handling
1419 properties apply: if you include a miniature script as one
1420 of the commands in your makefile you'll find that if you
1421 don't do anything about it then errors are not detected
1422 and <prgn>make</prgn> will blithely continue after
1426 Every time you put more than one shell command (this
1427 includes using a loop) in a makefile command you
1428 must make sure that errors are trapped. For
1429 simple compound commands, such as changing directory and
1430 then running a program, using <tt>&&</tt> rather
1431 than semicolon as a command separator is sufficient. For
1432 more complex commands including most loops and
1433 conditionals you should include a separate <tt>set -e</tt>
1434 command at the start of every makefile command that's
1435 actually one of these miniature shell scripts.</p></sect1>
1439 <heading>Obsolete constructs and libraries</heading>
1442 The include file <prgn><varargs.h></prgn> is
1443 provided to support end-users compiling very old software;
1444 the library <tt>libtermcap</tt> is provided to support the
1445 execution of software which has been linked against it
1446 (either old programs or those such as Netscape which are
1447 only available in binary form).</p>
1450 Debian packages should be patched to use
1451 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1458 <chapt id="controlfields"><heading>Control files and their fields</heading>
1461 Many of the tools in the package management suite manipulate
1462 data represented in a common format, known as <em>control
1463 data</em>. The data is often stored in <em>control
1464 files</em>. Binary and source packages have control files,
1465 and the <tt>.changes</tt> files which control the installation
1466 of uploaded files are also in control file format.
1467 <prgn>Dpkg</prgn>'s internal databases are in a similar
1471 <sect><heading>Syntax of control files</heading>
1474 A control file consists of one or more paragraphs of fields.
1475 The paragraphs are separated by blank lines. Some control
1476 files allow only one paragraph; others allow several, in
1477 which case each paragraph usually refers to a different
1478 package. (For example, in source packages, the first
1479 paragraph refers to the source package, and later paragraphs
1480 refer to binary packages generated from the source.)
1484 Each paragraph consists of a series of data fields; each
1485 field consists of the field name, followed by a colon and
1486 then the data/value associated with that field. It ends at
1487 the end of the line. Horizontal whitespace (spaces and
1488 tabs) may occur immediately before or after the value and is
1489 ignored there; it is conventional to put a single space
1490 after the colon. For example, a field might be:
1494 the field name is <tt>Package</tt> and the field value
1499 Some fields' values may span several lines; in this case
1500 each continuation line <em>must</em> start with a space or
1501 tab. Any trailing spaces or tabs at the end of individual
1502 lines of a field value are ignored.
1506 Except where otherwise stated only a single line of data is
1507 allowed and whitespace is not significant in a field body.
1508 Whitespace must not appear inside names (of packages,
1509 architectures, files or anything else) or version numbers,
1510 or between the characters of multi-character version
1515 Field names are not case-sensitive, but it is usual to
1516 capitalize the field names using mixed case as shown below.
1520 Blank lines, or lines consisting only of spaces and tabs,
1521 are not allowed within field values or between fields - that
1522 would mean a new paragraph.
1527 <sect><heading>List of fields</heading>
1529 This list here is not supposed to be exhaustive. Most fields
1530 are dealt with elsewhere in this document.
1532 <sect1 id="f-Package"><heading><tt>Package</tt>
1536 The name of the binary package. Package names consist of
1537 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1538 (plus, minus and full stop).
1542 They must be at least two characters long and must start
1543 with an alphanumeric character and not be all digits. The
1544 use of lowercase package names is strongly recommended
1545 unless the package you're building (or referring to, in
1546 other fields) is already using uppercase.</p>
1549 <sect1 id="f-Version"><heading><tt>Version</tt>
1553 This lists the source or binary package's version number -
1554 see <ref id="versions">.
1560 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1564 The most recent version of the standards (the policy
1565 manual and associated texts) with which the package
1566 complies. This is updated manually when editing the
1567 source package to conform to newer standards; it can
1568 sometimes be used to tell when a package needs attention.
1569 Its format is described above; see
1570 <ref id="standardsversion">.
1575 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1579 In a <tt>.changes</tt> file or parsed changelog output
1580 this contains the (space-separated) name(s) of the
1581 distribution(s) where this version of the package should
1582 be installed. Valid distributions are determined by the
1583 archive maintainers.
1585 Current distribution names are:
1587 <tag><em>stable</em></tag>
1590 This is the current `released' version of Debian
1591 GNU/Linux. Once the distribution is
1592 <em>stable</em> only security fixes and other
1593 major bug fixes are allowed. When changes are
1594 made to this distribution, the release number is
1595 increased (for example: 2.2r1 becomes 2.2r2 then
1600 <tag><em>unstable</em></tag>
1603 This distribution value refers to the
1604 <em>developmental</em> part of the Debian
1605 distribution tree. New packages, new upstream
1606 versions of packages and bug fixes go into the
1607 <em>unstable</em> directory tree. Download from
1608 this distribution at your own risk.
1612 <tag><em>testing</em></tag>
1615 This distribution value refers to the
1616 <em>testing</em> part of the Debian distribution
1617 tree. It receives its packages from the
1618 unstable distribution after a short time lag to
1619 ensure that there are no major issues with the
1620 unstable packages. It is less prone to breakage
1621 than unstable, but still risky. It is not
1622 possible to upload packages directly to
1627 <tag><em>frozen</em></tag>
1630 From time to time, the <em>frozen</em>
1631 distribution enters a state of `code-freeze' in
1632 anticipation of release as a <em>stable</em>
1633 version. During this period of testing only
1634 fixes for existing or newly-discovered bugs will
1635 be allowed. The exact details of this stage are
1636 determined by the Release Manager.
1640 <tag><em>experimental</em></tag>
1643 The packages with this distribution value are
1644 deemed by their maintainers to be high
1645 risk. Oftentimes they represent early beta or
1646 developmental packages from various sources that
1647 the maintainers want people to try, but are not
1648 ready to be a part of the other parts of the
1649 Debian distribution tree. Download at your own
1655 You should list <em>all</em> distributions that the
1656 package should be installed into.
1665 <chapt id="versions"><heading>Version numbering</heading>
1668 Every package has a version number recorded in its
1669 <tt>Version</tt> control file field.
1673 The package management system imposes an ordering on version
1674 numbers, so that it can tell whether packages are being up- or
1675 downgraded and so that package system front end applications
1676 can tell whether a package it finds available is newer than
1677 the one installed on the system. The version number format
1678 has the most significant parts (as far as comparison is
1679 concerned) at the beginning.
1683 The version number format is:
1684 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1688 The three components here are:
1690 <tag><var>epoch</var></tag>
1694 This is a single (generally small) unsigned integer. It
1695 may be omitted, in which case zero is assumed. If it is
1696 omitted then the <var>upstream_version</var> may not
1701 It is provided to allow mistakes in the version numbers
1702 of older versions of a package, and also a package's
1703 previous version numbering schemes, to be left behind.
1708 <tag><var>upstream_version</var></tag>
1712 This is the main part of the version number. It is
1713 usually the version number of the original (`upstream')
1714 package from which the <tt>.deb</tt> file has been made,
1715 if this is applicable. Usually this will be in the same
1716 format as that specified by the upstream author(s);
1717 however, it may need to be reformatted to fit into the
1718 package management system's format and comparison
1723 The comparison behavior of the package management system
1724 with respect to the <var>upstream_version</var> is
1725 described below. The <var>upstream_version</var>
1726 portion of the version number is mandatory.
1730 The <var>upstream_version</var> may contain only
1733 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1735 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1736 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1737 start with a digit. If there is no
1738 <var>debian_revision</var> then hyphens are not allowed;
1739 if there is no <var>epoch</var> then colons are not
1743 <tag><var>debian_revision</var></tag>
1747 This part of the version number specifies the version of
1748 the Debian package based on the upstream version. It
1749 may contain only alphanumerics and the characters
1750 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1751 compared in the same way as the
1752 <var>upstream_version</var> is.
1756 It is optional; if it isn't present then the
1757 <var>upstream_version</var> may not contain a hyphen.
1758 This format represents the case where a piece of
1759 software was written specifically to be turned into a
1760 Debian package, and so there is only one `debianization'
1761 of it and therefore no revision indication is required.
1765 It is conventional to restart the
1766 <var>debian_revision</var> at <tt>1</tt> each time the
1767 <var>upstream_version</var> is increased.
1771 The package management system will break the version
1772 number apart at the last hyphen in the string (if there
1773 is one) to determine the <var>upstream_version</var> and
1774 <var>debian_revision</var>. The absence of a
1775 <var>debian_revision</var> compares earlier than the
1776 presence of one (but note that the
1777 <var>debian_revision</var> is the least significant part
1778 of the version number).
1782 The <var>upstream_version</var> and <var>debian_revision</var>
1783 parts are compared by the package management system using the
1788 The strings are compared from left to right.
1792 First the initial part of each string consisting entirely of
1793 non-digit characters is determined. These two parts (one of
1794 which may be empty) are compared lexically. If a difference
1795 is found it is returned. The lexical comparison is a
1796 comparison of ASCII values modified so that all the letters
1797 sort earlier than all the non-letters.
1801 Then the initial part of the remainder of each string which
1802 consists entirely of digit characters is determined. The
1803 numerical values of these two parts are compared, and any
1804 difference found is returned as the result of the comparison.
1805 For these purposes an empty string (which can only occur at
1806 the end of one or both version strings being compared) counts
1811 These two steps (comparing and removing initial non-digit
1812 strings and initial digit strings) are repeated until a
1813 difference is found or both strings are exhausted.
1817 Note that the purpose of epochs is to allow us to leave behind
1818 mistakes in version numbering, and to cope with situations
1819 where the version numbering scheme changes. It is
1820 <em>not</em> intended to cope with version numbers containing
1821 strings of letters which the package management system cannot
1822 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1823 silly orderings (the author of this manual has heard of a
1824 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1825 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1826 <tt>2</tt> and so forth).
1830 If an upstream package has problematic version numbers they
1831 should be converted to a sane form for use in the
1832 <tt>Version</tt> field.
1836 <heading>Version numbers based on dates</heading>
1838 In general, Debian packages should use the same version
1839 numbers as the upstream sources.</p>
1842 However, in some cases where the upstream version number is
1843 based on a date (e.g., a development `snapshot' release) the
1844 package management system cannot handle these version
1845 numbers without epochs. For example, dpkg will consider
1846 `96May01' to be greater than `96Dec24'.</p>
1849 To prevent having to use epochs for every new upstream
1850 version, the version number should be changed to the
1851 following format in such cases: `19960501', `19961224'. It
1852 is up to the maintainer whether he/she wants to bother the
1853 upstream maintainer to change the version numbers upstream,
1857 Note that other version formats based on dates which are
1858 parsed correctly by the package management system should
1859 <em>not</em> be changed.</p>
1862 Native Debian packages (i.e., packages which have been
1863 written especially for Debian) whose version numbers include
1864 dates should always use the `YYYYMMDD' format.</p>
1868 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1870 <sect id="timestamps"><heading>Time Stamps</heading>
1872 Maintainers are encouraged to preserve the modification
1873 times of the upstream source files in a package, as far as
1874 is reasonably possible. Even though this is optional, this
1875 is still a good idea.
1878 The rationale is that there is some information conveyed
1879 by knowing the age of the file, for example, you could
1880 recognize that some documentation is very old by looking
1881 at the modification time, so it would be nice if the
1882 modification time of the upstream source would be
1889 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1890 main building script </heading>
1893 This file must be an executable makefile, and contains the
1894 package-specific recipes for compiling the package and
1895 building binary package(s) out of the source.
1899 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1900 so that it can be invoked by saying its name rather than
1901 invoking <prgn>make</prgn> explicitly.
1905 Since an interactive <tt>debian/rules</tt> script makes it
1906 impossible to auto-compile that package and also makes it
1907 hard for other people to reproduce the same binary
1908 package, all <strong>required targets</strong> MUST be
1909 non-interactive. At a minimum, required targets are the
1910 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1911 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1912 <em>binary-indep</em>, and <em>build</em>. It also follows
1913 that any target that these targets depend on must also be
1918 The targets which must be present are:
1920 <tag><tt>build</tt></tag>
1923 This should perform all non-interactive
1924 configuration and compilation of the package. If a
1925 package has an interactive pre-build configuration
1926 routine, the Debianised source package should be
1927 built after this has taken place, so that it can be
1928 built without rerunning the configuration.
1932 For some packages, notably ones where the same
1933 source tree is compiled in different ways to produce
1934 two binary packages, the <prgn>build</prgn> target
1935 does not make much sense. For these packages it is
1936 good enough to provide two (or more) targets
1937 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1938 for each of the ways of building the package, and a
1939 <prgn>build</prgn> target that does nothing. The
1940 <prgn>binary</prgn> target will have to build the
1941 package in each of the possible ways and make the
1942 binary package out of each.
1946 The <prgn>build</prgn> target must not do anything
1947 that might require root privilege.
1951 The <prgn>build</prgn> target may need to run
1952 <prgn>clean</prgn> first - see below.
1956 When a package has a configuration routine that
1957 takes a long time, or when the makefiles are poorly
1958 designed, or when <prgn>build</prgn> needs to run
1959 <prgn>clean</prgn> first, it is a good idea to
1960 <tt>touch build</tt> when the build process is
1961 complete. This will ensure that if <tt>debian/rules
1962 build</tt> is run again it will not rebuild the
1967 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1968 <tt>binary-indep</tt>
1972 The <prgn>binary</prgn> target must be all that is
1973 necessary for the user to build the binary
1974 package. All these targets are required to be
1975 non-interactive. It is split into two parts:
1976 <prgn>binary-arch</prgn> builds the packages' output
1977 files which are specific to a particular
1978 architecture, and <prgn>binary-indep</prgn> builds
1979 those which are not.
1983 <prgn>binary</prgn> may be (and commonly is) a target
1984 with no commands which simply depends on
1985 <prgn>binary-arch</prgn> and
1986 <prgn>binary-indep</prgn>.
1990 Both <prgn>binary-*</prgn> targets should depend on
1991 the <prgn>build</prgn> target, above, so that the
1992 package is built if it has not been already. It
1993 should then create the relevant binary package(s),
1994 using <prgn>dpkg-gencontrol</prgn> to make their
1995 control files and <prgn>dpkg-deb</prgn> to build
1996 them and place them in the parent of the top level
2001 If one of the <prgn>binary-*</prgn> targets has
2002 nothing to do (this will be always be the case if
2003 the source generates only a single binary package,
2004 whether architecture-dependent or not) it
2005 <em>must</em> still exist, and must always
2010 The <prgn>binary</prgn> targets must be invoked as
2015 <tag><tt>clean</tt></tag>
2019 This must undo any effects that the
2020 <prgn>build</prgn> and <prgn>binary</prgn> targets
2021 may have had, except that it should leave alone any
2022 output files created in the parent directory by a
2023 run of <prgn>binary</prgn>. This target must be
2028 If a <prgn>build</prgn> file is touched at the end
2029 of the <prgn>build</prgn> target, as suggested
2030 above, it should be removed as the first thing that
2031 <prgn>clean</prgn> does, so that running
2032 <prgn>build</prgn> again after an interrupted
2033 <prgn>clean</prgn> doesn't think that everything is
2038 The <prgn>clean</prgn> target may need to be
2039 invoked as root if <prgn>binary</prgn> has been
2040 invoked since the last <prgn>clean</prgn>, or if
2041 <prgn>build</prgn> has been invoked as root (since
2042 <prgn>build</prgn> may create directories, for
2047 <tag><tt>get-orig-source</tt> (optional)</tag>
2051 This target fetches the most recent version of the
2052 original source package from a canonical archive site
2053 (via FTP or WWW, for example), does any necessary
2054 rearrangement to turn it into the original source
2055 tar file format described below, and leaves it in the
2060 This target may be invoked in any directory, and
2061 should take care to clean up any temporary files it
2066 This target is optional, but providing it if
2067 possible is a good idea.
2073 The <prgn>build</prgn>, <prgn>binary</prgn> and
2074 <prgn>clean</prgn> targets must be invoked with a current
2075 directory of the package's top-level directory.
2080 Additional targets may exist in <tt>debian/rules</tt>,
2081 either as published or undocumented interfaces or for the
2082 package's internal use.
2086 The architecture we build on and build for is determined by
2087 make variables via dpkg-architecture. You can get the Debian
2088 architecture and the GNU style architecture specification
2089 string for the build machine as well as the host
2090 machine. Here is a list of supported make variables:
2091 <list compact="compact">
2093 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2096 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2097 specification string)</p>
2100 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
2103 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2109 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2110 the build machine or <tt>HOST</tt> for specification of the machine
2115 Backward compatibility can be provided in the rules file
2116 by setting the needed variables to suitable default
2117 values, please refer to the documentation of
2118 dpkg-architecture for details.
2122 It is important to understand that the <tt>DEB_*_ARCH</tt>
2123 string only determines which Debian architecture we are
2124 building on or for. It should not be used to get the CPU
2125 or system information; the GNU style variables should be
2130 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2134 This file records the changes to the Debian-specific parts of the
2138 Though there is nothing stopping an author who is also
2139 the Debian maintainer from using it for all their
2140 changes, it will have to be renamed if the Debian and
2141 upstream maintainers become different
2148 It has a special format which allows the package building
2149 tools to discover which version of the package is being
2150 built and find out other release-specific information.
2154 That format is a series of entries like this:
2156 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2158 * <var>change details</var>
2159 <var>more change details</var>
2160 * <var>even more change details</var>
2162 -- <var>maintainer name and email address</var> <var>date</var>
2167 <var>package</var> and <var>version</var> are the source
2168 package name and version number.
2172 <var>distribution(s)</var> lists the distributions where
2173 this version should be installed when it is uploaded - it
2174 is copied to the <tt>Distribution</tt> field in the
2175 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2179 <var>urgency</var> is the value for the <tt>Urgency</tt>
2180 field in the <tt>.changes</tt> file for the upload. It is
2181 not possible to specify an urgency containing commas; commas
2182 are used to separate
2183 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2184 <prgn>dpkg</prgn> changelog format (though there is
2185 currently only one useful <var>keyword</var>,
2190 The change details may in fact be any series of lines
2191 starting with at least two spaces, but conventionally each
2192 change starts with an asterisk and a separating space and
2193 continuation lines are indented so as to bring them in
2194 line with the start of the text above. Blank lines may be
2195 used here to separate groups of changes, if desired.
2199 The maintainer name and email address need <em>not</em>
2200 necessarily be those of the usual package maintainer.
2201 They should be the details of the person doing
2202 <em>this</em> version. The information here will be
2203 copied to the <tt>.changes</tt> file, and then later used
2204 to send an acknowledgement when the upload has been
2209 The <var>date</var> should be in RFC822 format
2212 This is generated by the <prgn>822-date</prgn>
2215 </footnote>; it should include the time zone specified
2216 numerically, with the time zone name or abbreviation
2217 optionally present as a comment.
2221 The first `title' line with the package name should start
2222 at the left hand margin; the `trailer' line with the
2223 maintainer and date details should be preceded by exactly
2224 one space. The maintainer details and the date must be
2225 separated by exactly two spaces.
2228 <sect1><heading>Defining alternative changelog formats</heading>
2231 It is possible to use a different format to the standard
2232 one, by providing a parser for the format you wish to
2236 A changelog parser must not interact with the user at
2242 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2243 and variable substitutions </heading>
2246 When <prgn>dpkg-gencontrol</prgn>,
2247 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2248 generate control files they do variable substitutions on
2249 their output just before writing it. Variable
2250 substitutions have the form
2251 <tt>${<var>variable-name</var>}</tt>. The optional file
2252 <tt>debian/substvars</tt> contains variable substitutions
2253 to be used; variables can also be set directly from
2254 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2255 source packaging commands, and certain predefined
2256 variables are available.
2260 The is usually generated and modified dynamically by
2261 <tt>debian/rules</tt> targets; in this case it must be
2262 removed by the <prgn>clean</prgn> target.
2266 See <manref name="dpkg-source" section="1"> for full
2267 details about source variable substitutions, including the
2268 format of <tt>debian/substvars</tt>.</p>
2271 <sect id="debianfiles"><heading><tt>debian/files</tt>
2275 This file is not a permanent part of the source tree; it
2276 is used while building packages to record which files are
2277 being generated. <prgn>dpkg-genchanges</prgn> uses it
2278 when it generates a <tt>.changes</tt> file.
2282 It should not exist in a shipped source package, and so it
2283 (and any backup files or temporary files such as
2287 <tt>files.new</tt> is used as a temporary file by
2288 <prgn>dpkg-gencontrol</prgn> and
2289 <prgn>dpkg-distaddfile</prgn> - they write a new
2290 version of <tt>files</tt> here before renaming it,
2291 to avoid leaving a corrupted copy if an error
2294 </footnote>) should be removed by the
2295 <prgn>clean</prgn> target. It may also be wise to
2296 ensure a fresh start by emptying or removing it at the
2297 start of the <prgn>binary</prgn> target.
2301 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2302 for the <tt>.deb</tt> file that will be created by
2303 <prgn>dpkg-deb</prgn> from the control file that it
2304 generates, so for most packages all that needs to be done
2305 with this file is to delete it in <prgn>clean</prgn>.
2309 If a package upload includes files besides the source
2310 package and any binary packages whose control files were
2311 made with <prgn>dpkg-gencontrol</prgn> then they should be
2312 placed in the parent of the package's top-level directory
2313 and <prgn>dpkg-distaddfile</prgn> should be called to add
2314 the file to the list in <tt>debian/files</tt>.</p>
2317 <sect id="restrictions"><heading>Restrictions on objects in source packages
2321 The source package may not contain any hard links
2324 This is not currently detected when building source
2325 packages, but only when extracting
2331 Hard links may be permitted at some point in the
2332 future, but would require a fair amount of
2335 </footnote>, device special files, sockets or setuid or
2339 Setgid directories are allowed.
2344 <sect id="descriptions"><heading>Descriptions of packages - the
2345 <tt>Description</tt> field </heading>
2348 The description is intended to describe the program to a user
2349 who has never met it before so that they know whether they
2350 want to install it. It should also give information about the
2351 significant dependencies and conflicts between this package
2352 and others, so that the user knows why these dependencies and
2353 conflicts have been declared.
2356 <sect1><heading>Notes about writing descriptions
2360 The single line synopsis should be kept brief - certainly
2361 under 80 characters.
2365 Do not include the package name in the synopsis line. The
2366 display software knows how to display this already, and you
2367 do not need to state it. Remember that in many situations
2368 the user may only see the synopsis line - make it as
2369 informative as you can.
2373 Do not try to continue the single line synopsis into the
2374 extended description. This will not work correctly when
2375 the full description is displayed, and makes no sense
2376 where only the summary (the single line synopsis) is
2381 The extended description should describe what the package
2382 does and how it relates to the rest of the system (in terms
2383 of, for example, which subsystem it is which part of).
2387 The description field needs to make sense to anyone, even
2388 people who have no idea about any of the things the
2392 The blurb that comes with a program in its
2393 announcements and/or <prgn>README</prgn> files is
2394 rarely suitable for use in a description. It is
2395 usually aimed at people who are already in the
2396 community where the package is used.
2402 Put important information first, both in the synopsis and
2403 extended description. Sometimes only the first part of the
2404 synopsis or of the description will be displayed. You can
2405 assume that there will usually be a way to see the whole
2406 extended description.
2410 You may include information about dependencies and so forth
2411 in the extended description, if you wish.
2415 Do not use tab characters. Their effect is not predictable.
2423 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2424 and installation procedure
2427 <sect><heading>Introduction to package maintainer scripts
2431 It is possible to supply scripts as part of a package which
2432 the package management system will run for you when your
2433 package is installed, upgraded or removed.
2437 These scripts should be the files <tt>preinst</tt>,
2438 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2439 control area of the package. They must be proper executable
2440 files; if they are scripts (which is recommended) they must
2441 start with the usual <tt>#!</tt> convention. They should be
2442 readable and executable by anyone, and not world-writable.
2446 The package management system looks at the exit status from
2447 these scripts. It is important that they exit with a
2448 non-zero status if there is an error, so that the package
2449 management system can stop its processing. For shell
2450 scripts this means that you <em>almost always</em> need to
2451 use <tt>set -e</tt> (this is usually true when writing shell
2452 scripts, in fact). It is also important, of course, that
2453 they don't exit with a non-zero status if everything went
2458 It is necessary for the error recovery procedures that the
2459 scripts be idempotent: i.e., invoking the same script several
2460 times in the same situation should do no harm. If the first
2461 call failed, or aborted half way through for some reason,
2462 the second call should merely do the things that were left
2463 undone the first time, if any, and exit with a success
2468 When a package is upgraded a combination of the scripts from
2469 the old and new packages is called in amongst the other
2470 steps of the upgrade procedure. If your scripts are going
2471 to be at all complicated you need to be aware of this, and
2472 may need to check the arguments to your scripts.
2476 Broadly speaking the <prgn>preinst</prgn> is called before
2477 (a particular version of) a package is installed, and the
2478 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2479 before (a version of) a package is removed and the
2480 <prgn>postrm</prgn> afterwards.
2483 <p> Programs called from maintainer scripts should not
2484 normally have a path prepended to them. Before installation
2485 is started the package management system checks to see if
2486 the programs <prgn>ldconfig</prgn>,
2487 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2488 and <prgn>update-rc.d</prgn> can be found via the
2489 <tt>PATH</tt> environment variable. Those programs, and any
2490 other program that one would expect to on the <tt>PATH</tt>,
2491 should thus be invoked without an absolute
2492 pathname. Maintainer scripts should also not reset the
2493 <tt>PATH</tt>, though they might choose to modify it by pre-
2494 or appending package-specific directories. These
2495 considerations really apply to all shell scripts.</p>
2498 <heading>Maintainer scripts Idempotency</heading>
2501 It is very important to make maintainer scripts
2505 That means that if it runs successfully or fails
2506 and then you call it again it doesn't bomb out,
2507 but just ensures that everything is the way it
2510 </footnote> This is so that if an error occurs, the
2511 user interrupts <prgn>dpkg</prgn> or some other
2512 unforeseen circumstance happens you don't leave the
2513 user with a badly-broken package.
2517 <heading>Controlling terminal for maintainer scripts</heading>
2520 The maintainer scripts are guaranteed to run with a
2521 controlling terminal and can interact with the user.
2522 If they need to prompt for passwords, do full-screen
2523 interaction or something similar you should do these
2524 things to and from <tt>/dev/tty</tt>, since
2525 <prgn>dpkg</prgn> will at some point redirect scripts'
2526 standard input and output so that it can log the
2527 installation process. Likewise, because these scripts
2528 may be executed with standard output redirected into a
2529 pipe for logging purposes, Perl scripts should set
2530 unbuffered output by setting <tt>$|=1</tt> so that the
2531 output is printed immediately rather than being
2536 Each script should return a zero exit status for
2537 success, or a nonzero one for failure.
2541 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2546 <list compact="compact">
2548 <p><var>new-preinst</var> <tt>install</tt></p>
2551 <p><var>new-preinst</var> <tt>install</tt>
2552 <var>old-version</var></p>
2555 <p><var>new-preinst</var> <tt>upgrade</tt>
2556 <var>old-version</var></p>
2559 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2560 <var>new-version</var>
2566 <list compact="compact">
2568 <p><var>postinst</var> <tt>configure</tt>
2569 <var>most-recently-configured-version</var></p>
2572 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2573 <var>new version</var></p>
2576 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2577 <tt>in-favour</tt> <var>package</var>
2578 <var>new-version</var></p>
2582 <var>deconfigured's-postinst</var>
2583 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2584 <var>failed-install-package</var> <var>version</var>
2585 <tt>removing</tt> <var>conflicting-package</var>
2592 <list compact="compact">
2594 <p><var>prerm</var> <tt>remove</tt></p>
2597 <p><var>old-prerm</var> <tt>upgrade</tt>
2598 <var>new-version</var></p>
2601 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2602 <var>old-version</var></p>
2605 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2606 <tt>in-favour</tt> <var>package</var>
2607 <var>new-version</var></p>
2611 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2612 <tt>in-favour</tt> <var>package-being-installed</var>
2613 <var>version</var> <tt>removing</tt>
2614 <var>conflicting-package</var>
2621 <list compact="compact">
2623 <p><var>postrm</var> <tt>remove</tt></p>
2626 <p><var>postrm</var> <tt>purge</tt></p>
2630 <var>old-postrm</var> <tt>upgrade</tt>
2631 <var>new-version</var></p>
2634 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2635 <var>old-version</var></p>
2638 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2641 <p><var>new-postrm</var> <tt>abort-install</tt>
2642 <var>old-version</var></p>
2645 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2646 <var>old-version</var></p>
2650 <var>disappearer's-postrm</var> <tt>disappear</tt>
2651 <var>overwriter</var>
2652 <var>overwriter-version</var></p></item>
2657 <sect id="unpackphase"><heading>Details of unpack phase of
2658 installation or upgrade
2662 The procedure on installation/upgrade/overwrite/disappear
2663 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2664 stage of <tt>dpkg --install</tt>) is as follows. In each
2665 case if an error occurs the actions are, in general, run
2666 backwards - this means that the maintainer scripts are run
2667 with different arguments in reverse order. These are the
2668 `error unwind' calls listed below.
2675 <p>If a version of the package is already
2678 <var>old-prerm</var> upgrade <var>new-version</var>
2683 If the script runs but exits with a non-zero
2684 exit status, <prgn>dpkg</prgn> will attempt:
2686 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2688 Error unwind, for both the above cases:
2690 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2698 <p>If a `conflicting' package is being removed at the same time:
2702 If any packages depended on that conflicting
2703 package and <tt>--auto-deconfigure</tt> is
2704 specified, call, for each such package:
2706 <var>deconfigured's-prerm</var> deconfigure \
2707 in-favour <var>package-being-installed</var> <var>version</var> \
2708 removing <var>conflicting-package</var> <var>version</var>
2712 <var>deconfigured's-postinst</var> abort-deconfigure \
2713 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2714 removing <var>conflicting-package</var> <var>version</var>
2716 The deconfigured packages are marked as
2717 requiring configuration, so that if
2718 <tt>--install</tt> is used they will be
2719 configured again if possible.</p>
2722 <p>To prepare for removal of the conflicting package, call:
2724 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2728 <var>conflictor's-postinst</var> abort-remove \
2729 in-favour <var>package</var> <var>new-version</var>
2740 <p>If the package is being upgraded, call:
2742 <var>new-preinst</var> upgrade <var>old-version</var>
2747 Otherwise, if the package had some configuration
2748 files from a previous version installed (i.e., it
2749 is in the `configuration files only' state):
2751 <var>new-preinst</var> install <var>old-version</var>
2755 <p>Otherwise (i.e., the package was completely purged):
2757 <var>new-preinst</var> install
2759 Error unwind versions, respectively:
2761 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2762 <var>new-postrm</var> abort-install <var>old-version</var>
2763 <var>new-postrm</var> abort-install
2773 The new package's files are unpacked, overwriting any
2774 that may be on the system already, for example any
2775 from the old version of the same package or from
2776 another package (backups of the old files are left
2777 around, and if anything goes wrong the package
2778 management system will attempt to put them back as
2779 part of the error unwind).
2783 It is an error for a package to contains files which
2784 are on the system in another package, unless
2785 <tt>Replaces</tt> is used (see <ref id="replaces">).
2786 Currently the <tt>--force-overwrite</tt> flag is
2787 enabled, downgrading it to a warning, but this may not
2792 It is a more serious error for a package to contain a
2793 plain file or other kind of non-directory where another
2794 package has a directory (again, unless
2795 <tt>Replaces</tt> is used). This error can be
2796 overridden if desired using
2797 <tt>--force-overwrite-dir</tt>, but this is not
2802 Packages which overwrite each other's files produce
2803 behavior which though deterministic is hard for the
2804 system administrator to understand. It can easily
2805 lead to `missing' programs if, for example, a package
2806 is installed which overwrites a file from another
2807 package, and is then removed again.
2810 Part of the problem is due to what is arguably a
2811 bug in <prgn>dpkg</prgn>.
2817 A directory will never be replaced by a symbolic links
2818 to a directory or vice versa; instead, the existing
2819 state (symlink or not) will be left alone and
2820 <prgn>dpkg</prgn> will follow the symlink if there is
2828 <p>If the package is being upgraded, call
2830 <var>old-postrm</var> upgrade <var>new-version</var>
2834 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2836 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2838 Error unwind, for both cases:
2840 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2846 This is the point of no return - if
2847 <prgn>dpkg</prgn> gets this far, it won't back off
2848 past this point if an error occurs. This will
2849 leave the package in a fairly bad state, which
2850 will require a successful re-installation to clear
2851 up, but it's when <prgn>dpkg</prgn> starts doing
2852 things that are irreversible.
2857 Any files which were in the old version of the package
2858 but not in the new are removed.</p>
2861 <p>The new file list replaces the old.</p>
2864 <p>The new maintainer scripts replace the old.</p>
2868 <p>Any packages all of whose files have been overwritten during the
2869 installation, and which aren't required for
2870 dependencies, are considered to have been removed.
2871 For each such package,
2874 <p><prgn>dpkg</prgn> calls:
2876 <var>disappearer's-postrm</var> disappear \
2877 <var>overwriter</var> <var>overwriter-version</var>
2882 <p>The package's maintainer scripts are removed.
2887 It is noted in the status database as being in a
2888 sane state, namely not installed (any conffiles
2889 it may have are ignored, rather than being
2890 removed by <prgn>dpkg</prgn>). Note that
2891 disappearing packages do not have their prerm
2892 called, because <prgn>dpkg</prgn> doesn't know
2893 in advance that the package is going to
2902 Any files in the package we're unpacking that are also
2903 listed in the file lists of other packages are removed
2904 from those lists. (This will lobotomize the file list
2905 of the `conflicting' package if there is one.)
2910 The backup files made during installation, above, are
2917 The new package's status is now sane, and recorded as
2918 `unpacked'. Here is another point of no return - if
2919 the conflicting package's removal fails we do not
2920 unwind the rest of the installation; the conflicting
2921 package is left in a half-removed limbo.
2926 If there was a conflicting package we go and do the
2927 removal actions (described below), starting with the
2928 removal of the conflicting package's files (any that
2929 are also in the package being installed have already
2930 been removed from the conflicting package's file list,
2931 and so do not get removed now).
2938 <sect><heading>Details of configuration</heading>
2941 When we configure a package (this happens with <tt>dpkg
2942 --install</tt>, or with <tt>--configure</tt>), we first
2943 update the conffiles and then call:
2945 <var>postinst</var> configure <var>most-recently-configured-version</var>
2950 No attempt is made to unwind after errors during
2955 If there is no most recently configured version
2956 <prgn>dpkg</prgn> will pass a null argument; older versions
2957 of dpkg may pass <tt><unknown></tt> (including the
2958 angle brackets) in this case. Even older ones do not pass a
2959 second argument at all, under any circumstances.
2963 <sect><heading>Details of removal and/or configuration purging
2971 <var>prerm</var> remove
2977 The package's files are removed (except conffiles).
2982 <var>postrm</var> remove
2986 <p>All the maintainer scripts except the postrm are removed.
2990 If we aren't purging the package we stop here. Note
2991 that packages which have no postrm and no conffiles
2992 are automatically purged when removed, as there is no
2993 difference except for the <prgn>dpkg</prgn>
2998 The conffiles and any backup files (<tt>~</tt>-files,
2999 <tt>#*#</tt> files, <tt>%</tt>-files,
3000 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3004 <var>postrm</var> purge
3008 <p>The package's file list is removed.</p>
3011 No attempt is made to unwind after errors during
3017 <chapt id="relationships"><heading>Declaring relationships between
3021 Packages can declare in their control file that they have
3022 certain relationships to other packages - for example, that
3023 they may not be installed at the same time as certain other
3024 packages, and/or that they depend on the presence of others,
3025 or that they should overwrite files in certain other packages
3030 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3031 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3032 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3036 Source packages may declare relationships to binary packages,
3037 saying that they require certain binary packages to be
3038 installed or absent at the time of building the package.
3042 This is done using the <tt>Build-Depends</tt>,
3043 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3044 <tt>Build-Conflicts-Indep</tt> control file fields.
3047 <sect id="depsyntax"><heading>Syntax of relationship fields
3051 These fields all have a uniform syntax. They are a list of
3052 package names separated by commas.
3056 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3057 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3058 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3059 control file fields of the package, which declare
3060 dependencies on other packages, the package names listed may
3061 also include lists of alternative package names, separated
3062 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3063 a case, the presence of any one of the alternative packages
3064 is installed, that part of the dependency is considered to
3069 All the fields except <tt>Provides</tt> may restrict their
3070 applicability to particular versions of each named package.
3071 This is done in parentheses after each individual package
3072 name; the parentheses should contain a relation from the
3073 list below followed by a version number, in the format
3074 described in <ref id="versions">.
3078 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3079 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3080 strictly earlier, earlier or equal, exactly equal, later or
3081 equal and strictly later, respectively. The forms
3082 <tt><</tt> and <tt>></tt> were used to mean
3083 earlier/later or equal, rather than strictly earlier/later,
3084 so they should not appear in new packages (though
3085 <prgn>dpkg</prgn> still supports them).
3089 Whitespace may appear at any point in the version
3090 specification, and must appear where it's necessary to
3091 disambiguate; it is not otherwise significant. For
3092 consistency and in case of future changes to
3093 <prgn>dpkg</prgn> it is recommended that a single space be
3094 used after a version relationship and before a version
3095 number; it is usual also to put a single space after each
3096 comma, on either side of each vertical bar, and before each
3105 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3110 All fields that specify build-time relationships
3111 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3112 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3113 may be restricted to a certain set of architectures. This
3114 is done in brackets after each individual package name and
3115 the optional version specification. The brackets enclose a
3116 list of Debian architecture names separated by whitespace.
3117 Exclamation marks may be prepended to each of the names.
3118 (It is not permitted for some names to be prepended with
3119 exclamation marks and others not.) If the current Debian
3120 host architecture is not in this list and there are no
3121 exclamation marks in the list, or it is in the list with a
3122 prepended exclamation mark, the package name and the
3123 associated version specification are ignored completely for
3124 the purposes of defining the relationships.
3131 Build-Depends-Indep: texinfo
3132 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3133 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3139 <heading>Binary Dependencies - <tt>Depends</tt>,
3140 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3141 <tt>Pre-Depends</tt>
3145 These five fields are used to declare a dependency
3146 relationship by one package on another. They appear in the
3147 depending package's control file.
3151 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3152 (discussed below) take effect <em>only</em> when a package
3153 is to be configured. They do not prevent a package being on
3154 the system in an unconfigured state while its dependencies
3155 are unsatisfied, and it is possible to replace a package
3156 whose dependencies are satisfied and which is properly
3157 installed with a different version whose dependencies are
3158 not and cannot be satisfied; when this is done the depending
3159 package will be left unconfigured (since attempts to
3160 configure it will give errors) and will not function
3165 For this reason packages in an installation run are usually
3166 all unpacked first and all configured later; this gives
3167 later versions of packages with dependencies on later
3168 versions of other packages the opportunity to have their
3169 dependencies satisfied.
3173 Thus <tt>Depends</tt> allows package maintainers to impose
3174 an order in which packages should be configured.
3176 <tag><tt>Depends</tt></tag>
3179 <p>This declares an absolute dependency.
3183 The <tt>Depends</tt> field should be used if the
3184 depended-on package is required for the depending
3185 package to provide a significant amount of
3189 <tag><tt>Recommends</tt></tag>
3191 <p>This declares a strong, but not absolute, dependency.
3195 The <tt>Recommends</tt> field should list packages
3196 that would be found together with this one in all but
3197 unusual installations.</p>
3200 <tag><tt>Suggests</tt></tag>
3204 This is used to declare that one package may be more
3205 useful with one or more others. Using this field
3206 tells the packaging system and the user that the
3207 listed packages are related to this one and can
3208 perhaps enhance its usefulness, but that installing
3209 this one without them is perfectly reasonable.
3213 <tag><tt>Enhances</tt></tag>
3216 This field is similar to Suggests but works in the
3217 opposite direction. It is used to declare that a
3218 package can enhance the functionality of another
3223 <tag><tt>Pre-Depends</tt></tag>
3227 This field is like <tt>Depends</tt>, except that it
3228 also forces <prgn>dpkg</prgn> to complete installation
3229 of the packages named before even starting the
3230 installation of the package which declares the
3235 <tt>Pre-Depends</tt> should be used sparingly,
3236 preferably only by packages whose premature upgrade or
3237 installation would hamper the ability of the system to
3238 continue with any upgrade that might be in progress.
3242 When the package declaring it is being configured, a
3243 <tt>Pre-Dependency</tt> will be considered satisfied
3244 only if the depending package has been correctly
3245 configured, just as if an ordinary <tt>Depends</tt>
3250 However, when a package declaring a Pre-dependency is
3251 being unpacked the predependency can be satisfied even
3252 if the depended-on package(s) are only unpacked or
3253 half-configured, provided that they have been
3254 configured correctly at some point in the past (and
3255 not removed or partially removed since). In this case
3256 both the previously-configured and currently unpacked
3257 or half-configured versions must satisfy any version
3258 clause in the <tt>Pre-Depends</tt> field.
3264 When selecting which level of dependency to use you should
3265 consider how important the depended-on package is to the
3266 functionality of the one declaring the dependency. Some
3267 packages are composed of components of varying degrees of
3268 importance. Such a package should list using
3269 <tt>Depends</tt> the package(s) which are required by the
3270 more important components. The other components'
3271 requirements may be mentioned as Suggestions or
3272 Recommendations, as appropriate to the components' relative
3277 <sect id="conflicts"><heading>Alternative binary packages -
3278 <tt>Conflicts</tt> and <tt>Replaces</tt>
3282 When one binary package declares a conflict with another
3283 <prgn>dpkg</prgn> will refuse to allow them to be installed
3284 on the system at the same time.
3288 If one package is to be installed, the other must be removed
3289 first - if the package being installed is marked as
3290 replacing (<ref id="replaces">) the one on the system, or
3291 the one on the system is marked as deselected, or both
3292 packages are marked <tt>Essential</tt>, then
3293 <prgn>dpkg</prgn> will automatically remove the package
3294 which is causing the conflict, otherwise it will halt the
3295 installation of the new package with an error. This
3296 mechanism specifically doesn't work when the installed
3297 package is <tt>Essential</tt>, but the new package is not.
3302 A package will not cause a conflict merely because its
3303 configuration files are still installed; it must be at least
3308 A special exception is made for packages which declare a
3309 conflict with their own package name, or with a virtual
3310 package which they provide (see below): this does not
3311 prevent their installation, and allows a package to conflict
3312 with others providing a replacement for it. You use this
3313 feature when you want the package in question to be the only
3314 package providing something.
3318 A <tt>Conflicts</tt> entry should almost never have an
3319 `earlier than' version clause. This would prevent
3320 <prgn>dpkg</prgn> from upgrading or installing the package
3321 which declared such a conflict until the upgrade or removal
3322 of the conflicted-with package had been completed.
3326 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3330 As well as the names of actual (`concrete') packages, the
3331 package relationship fields <tt>Depends</tt>,
3332 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3333 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3334 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3335 mention virtual packages.
3339 A virtual package is one which appears in the
3340 <tt>Provides</tt> control file field of another package.
3341 The effect is as if the package(s) which provide a
3342 particular virtual package name had been listed by name
3343 everywhere the virtual package name appears.
3347 If there are both a real and a virtual package of the same
3348 name then the dependency may be satisfied (or the conflict
3349 caused) by either the real package or any of the virtual
3350 packages which provide it. This is so that, for example,
3356 and someone else releases an xemacs package they can say
3360 </example> and all will work in the interim (until a purely
3361 virtual package name is decided on and the <tt>emacs</tt>
3362 and <tt>vm</tt> packages are changed to use it).
3366 If a dependency or a conflict has a version number attached
3367 then only real packages will be considered to see whether
3368 the relationship is satisfied (or the prohibition violated,
3369 for a conflict) - it is assumed that a real package which
3370 provides the virtual package is not of the `right' version.
3371 So, a <tt>Provides</tt> field may not contain version
3372 numbers, and the version number of the concrete package
3373 which provides a particular virtual package will not be
3374 looked at when considering a dependency on or conflict with
3375 the virtual package name.
3379 It is likely that the ability will be added in a future
3380 release of <prgn>dpkg</prgn> to specify a version number for
3381 each virtual package it provides. This feature is not yet
3382 present, however, and is expected to be used only
3387 If you want to specify which of a set of real packages should be the
3388 default to satisfy a particular dependency on a virtual package, you
3389 should list the real package as an alternative before the virtual.
3394 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3395 files and replacing packages
3399 The <tt>Replaces</tt> control file field has two purposes,
3400 which come into play in different situations.
3404 Virtual packages (<ref id="virtual">) are not considered
3405 when looking at a <tt>Replaces</tt> field - the packages
3406 declared as being replaced must be mentioned by their real
3410 <sect1><heading>Overwriting files in other packages
3414 Firstly, as mentioned before, it is usually an error for a
3415 package to contain files which are on the system in
3416 another package, though currently the
3417 <tt>--force-overwrite</tt> flag is enabled by default,
3418 downgrading the error to a warning,
3422 If the overwriting package declares that it replaces the
3423 one containing the file being overwritten then
3424 <prgn>dpkg</prgn> will proceed, and replace the file from
3425 the old package with that from the new. The file will no
3426 longer be listed as `owned' by the old package.
3430 If a package is completely replaced in this way, so that
3431 <prgn>dpkg</prgn> does not know of any files it still
3432 contains, it is considered to have disappeared. It will
3433 be marked as not wanted on the system (selected for
3434 removal) and not installed. Any conffiles details noted
3435 in the package will be ignored, as they will have been
3436 taken over by the replacing package(s). The package's
3437 <prgn>postrm</prgn> script will be run to allow the
3438 package to do any final cleanup required. See <ref
3439 id="mscriptsinstact">.
3443 In the future <prgn>dpkg</prgn> will discard files which
3444 would overwrite those from an already installed package
3445 which declares that it replaces the package being
3446 installed. This is so that you can install an older
3447 version of a package without problems.
3451 This usage of <tt>Replaces</tt> only takes effect when
3452 both packages are at least partially on the system at
3453 once, so that it can only happen if they do not conflict
3454 or if the conflict has been overridden.</p>
3457 <sect1><heading>Replacing whole packages, forcing their
3462 Secondly, <tt>Replaces</tt> allows the packaging system to
3463 resolve which package should be removed when there is a
3464 conflict - see <ref id="conflicts">. This usage only
3465 takes effect when the two packages <em>do</em> conflict,
3466 so that the two effects do not interfere with each other.
3471 <sect><heading>Relationships between source and binary packages -
3472 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3473 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3477 A source package may declare a dependency or a conflict on a
3478 binary package. This is done with the control file fields
3479 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3480 <tt>Build-Conflicts</tt>, and
3481 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3482 the dependencies and conflicts they define must be satisfied
3483 (as defined earlier for binary packages), when one of the
3484 targets in <tt>debian/rules</tt> that the particular field
3485 applies to is invoked.
3488 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3491 The <tt>Build-Depends</tt> and
3492 <tt>Build-Conflicts</tt> fields apply to the targets
3493 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3494 and <tt>binary-indep</tt>.
3497 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3500 The <tt>Build-Depends-Indep</tt> and
3501 <tt>Build-Conflicts-Indep</tt> fields apply to the
3502 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3513 <chapt id="conffiles"><heading>Configuration file handling
3517 <prgn>dpkg</prgn> can do a certain amount of automatic
3518 handling of package configuration files.
3522 Whether this mechanism is appropriate depends on a number of
3523 factors, but basically there are two approaches to any
3524 particular configuration file.
3528 The easy method is to ship a best-effort configuration in the
3529 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3530 handle updates. If the user is unlikely to want to edit the
3531 file, but you need them to be able to without losing their
3532 changes, and a new package with a changed version of the file
3533 is only released infrequently, this is a good approach.
3537 The hard method is to build the configuration file from
3538 scratch in the <prgn>postinst</prgn> script, and to take the
3539 responsibility for fixing any mistakes made in earlier
3540 versions of the package automatically. This will be
3541 appropriate if the file is likely to need to be different on
3546 <chapt id="sharedlibs"><heading>Shared libraries
3550 Packages containing shared libraries must be constructed with
3551 a little care to make sure that the shared library is always
3552 available. This is especially important for packages whose
3553 shared libraries are vitally important, such as the libc.
3557 Firstly, your package should install the shared libraries
3558 under their normal names. For example, the
3559 <prgn>libgdbm1</prgn> package should install
3560 <tt>libgdbm.so.1.7.3</tt> as
3561 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3562 renamed or re-linked by any prerm or postrm scripts;
3563 <prgn>dpkg</prgn> will take care of renaming things safely
3564 without affecting running programs, and attempts to interfere
3565 with this are likely to lead to problems.
3569 Secondly, your package should include the symlink that
3570 <prgn>ldconfig</prgn> would create for the shared libraries.
3571 For example, the <prgn>libgdbm1</prgn> package should include
3572 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3573 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3574 <prgn>ld.so</prgn> can find the library in between the time
3575 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3576 in the <prgn>postinst</prgn> script. Furthermore, older
3577 versions of the package management system required the library
3578 must be placed before the symlink pointing to it in the
3579 <tt>.deb</tt> file. This is so that by the time
3580 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3581 the previous symlink pointing at an older version of the
3582 library) the new shared library is already in place.
3583 Unfortunately, this was not not always possible, since it
3584 highly depends on the behavior of the file system. Some
3585 file systems (such as reiserfs) will reorder the files so it
3586 doesn't matter in what order you create them. Starting with
3587 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3588 files itself when building a package.
3592 Thirdly, the development package should contain a symlink for
3593 the shared library without a version number. For example, the
3594 <tt>libgdbm1-dev</tt> package should include a symlink from
3595 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3596 symlink is needed by <prgn>ld</prgn> when compiling packages
3597 as it will only look for <tt>libgdm.so</tt> and
3598 <tt>libgdm.a</tt> when compiling dynamically or statically,
3603 Any package installing shared libraries in a directory that's listed
3604 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3605 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3606 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3607 script if and only if the first argument is `configure'. However, it
3608 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3609 scripts in the case where the package is being upgraded (see <ref
3610 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3611 that <prgn>dpkg</prgn> uses for the files while it is
3612 installing them and will make the shared library links point
3613 to them, just before <prgn>dpkg</prgn> continues the
3614 installation and removes the links!
3617 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3621 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3622 required when your package provides shared libraries.
3626 Each line is of the form:
3628 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3633 <var>library-name</var> is the name of the shared library,
3634 for example <tt>libc5</tt>.
3638 <var>version-or-soname</var> is the soname of the library -
3639 i.e., the thing that must exactly match for the library to be
3640 recognized by <prgn>ld.so</prgn>. Usually this is the major
3641 version number of the library.
3645 <var>dependencies</var> has the same syntax as a dependency
3646 field in a binary package control file. It should give
3647 details of which package(s) are required to satisfy a binary
3648 built against the version of the library contained in the
3649 package. See <ref id="depsyntax">.
3653 For example, if the package <tt>foo</tt> contains
3654 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3655 <tt>libfoo.so.1</tt>, and the first version of the package
3656 which contained a minor number of at least <tt>2.3</tt> was
3657 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3660 libfoo 1 foo (>= 1.2.3-1)
3665 The version-specific dependency is to avoid warnings from
3666 <prgn>ld.so</prgn> about using older shared libraries with
3670 <sect><heading>Further Technical information on
3671 <tt>shlibs</tt></heading>
3673 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3677 The <tt>debian/shlibs</tt> file provides a way of checking
3678 for shared library dependencies on packaged binaries.
3679 They are intended to be used by package maintainers to
3680 make their lives easier.
3684 Other <tt>shlibs</tt> files that exist on a Debian system are
3686 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3687 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3688 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3689 <item> <p><tt>debian/shlibs.local</tt></p></item>
3691 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3692 creating a binary package.</p>
3695 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3699 <prgn>dpkg-shlibdeps</prgn>
3700 determines the shared libraries directly
3703 It used to do this by calling <prgn>ldd</prgn>, but it
3704 now calls <prgn>objdump</prgn> to do this. This
3705 requires a couple of changes in the way that packages
3709 A binary <tt>foo</tt> directly uses a library
3710 <tt>libbar</tt> if it is linked with that
3711 library. Other libraries that are needed by
3712 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3713 and the dynamic linker will load them automatically
3714 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3715 lists all of the libraries used, both directly and
3716 indirectly; but <prgn>objdump</prgn> only lists the
3717 directly linked libraries. A package only needs to
3718 depend on the libraries it is directly linked to,
3719 since the dependencies for those libraries should
3720 automatically pull in the other libraries.
3723 This change does mean a change in the way packages are
3724 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3725 only run on binaries. But since we will now rely on the
3726 libraries depending on the libraries they themselves
3727 need, the packages containing those libraries will
3728 need to run <prgn>dpkg-shlibdeps</prgn> on the
3732 A good example where this would help us is the current
3733 mess with multiple version of the <tt>mesa</tt>
3734 library. With the <prgn>ldd</prgn>-based system, every
3735 package that uses <tt>mesa</tt> needs to add a
3736 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3737 to handle the glide <tt>mesa</tt> variant. With an
3738 <prgn>objdump</prgn>-based system this isn't necessary
3739 anymore and would have saved everyone a lot of work.
3742 Another example: we could update <tt>libimlib</tt>
3743 with a new version that supports a new graphics format
3744 called dgf. If we use the old <prgn>ldd</prgn> method,
3745 every package that uses <tt>libimlib</tt> would need
3746 to be recompiled so it would also depend on
3747 <tt>libdgf</tt> or it wouldn't run due to missing
3748 symbols. However with the new system, packages using
3749 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3750 having the dependency on <tt>libdgf</tt> and wouldn't
3754 used by the compiled binaries and libraries passed through
3755 on its command line.
3759 For each shared library linked to,
3760 <prgn>dpkg-shlibdeps</prgn> needs to know
3761 <list compact="compact">
3762 <item><p>the package containing the library, and</p></item>
3763 <item><p>the library version number,</p></item>
3765 and it scans the following files in this order:
3766 <enumlist compact="compact">
3767 <item><p><tt>debian/shlibs.local</tt></p></item>
3768 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3769 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3770 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3775 <sect1><heading><em>Who</em> maintains the various
3776 <tt>shlibs</tt> files?
3780 <list compact="compact">
3782 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3787 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3788 - the maintainer of each package</p>
3792 <tt>/etc/dpkg/shlibs.override</tt> - the local
3793 system administrator</p>
3796 <p><tt>debian/shlibs.local</tt> - the maintainer of
3801 The <tt>shlibs.default</tt> file is managed by
3802 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3803 that are provided by <prgn>dpkg</prgn> are just there to
3804 fix things until the shared library packages all have
3805 <tt>shlibs</tt> files.
3809 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3810 the <tt>shlibs</tt> files
3813 <sect2><heading>If your package doesn't provide a shared
3818 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3819 <tt>debian/rules</tt> file. If your package contains
3820 only binaries (e.g. no scripts) use:
3822 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3824 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3825 done. If it does complain you might need to create your
3826 own <tt>debian/shlibs.local</tt> file.</p>
3829 <sect2><heading>If your package provides a shared library
3833 Create a <tt>debian/shlibs</tt> file and let
3834 <tt>debian/rules</tt> install it in the control area:
3836 install -m644 debian/shlibs debian/tmp/DEBIAN
3838 If your package contains additional binaries see above.
3843 <sect1><heading><em>How</em> to write
3844 <tt>debian/shlibs.local</tt>
3848 This file is intended only as a <em>temporary</em> fix if
3849 your binaries depend on a library which doesn't provide
3850 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3854 Let's assume you are packaging a binary <tt>foo</tt>. Your
3855 output in building the package might look like this.
3858 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3859 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3860 libc.so.6 => /lib/libc.so.6 (0x40114000)
3861 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3863 And when you ran <prgn>dpkg-shlibdeps</prgn>
3865 $ dpkg-shlibdeps -O foo
3866 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3867 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3868 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3870 The <prgn>foo</prgn> binary depends on the
3871 <prgn>libbar</prgn> shared library, but no package seems
3872 to provide a <tt>*.shlibs</tt> file in
3873 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3879 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3880 bar1: /usr/X11R6/lib/libbar.so.1.0
3881 $ dpkg -s bar1 | grep Version
3884 This tells us that the <prgn>bar1</prgn> package, version
3885 1.0-1 is the one we are using. Now we can create our own
3886 <tt>debian/shlibs.local</tt> to temporarily fix the above
3887 problem. Include the following line into your
3888 <tt>debian/shlibs.local</tt> file.
3890 libbar 1 bar1 (>= 1.0-1)
3892 Now your package build should work. As soon as the
3893 maintainer of <prgn>libbar1</prgn> provides a
3894 <tt>shlibs</tt> file, you can remove your
3895 <tt>debian/shlibs.local</tt> file.
3901 <chapt><heading>The Operating System</heading>
3905 <heading>File system hierarchy</heading>
3909 <heading>Linux File system Structure</heading>
3912 The location of all installed files and directories must
3913 comply with the Linux File system Hierarchy Standard
3914 (FHS). The latest version of this document can be found
3915 alongside this manual or on
3916 <url id="http://www.pathname.com/fhs/">.
3917 Specific questions about following the standard may be
3918 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3919 Quinlan, the FHS coordinator, at
3920 <email>quinlan@pathname.com</email>.</p></sect1>
3924 <heading>Site-specific programs</heading>
3927 As mandated by the FHS, packages must not place any
3928 files in <tt>/usr/local</tt>, either by putting them in
3929 the file system archive to be unpacked by <prgn>dpkg</prgn>
3930 or by manipulating them in their maintainer scripts.</p>
3933 However, the package may create empty directories below
3934 <tt>/usr/local</tt> so that the system administrator knows
3935 where to place site-specific files. These directories
3936 should be removed on package removal if they are
3940 Note, that this applies only to directories <em>below</em>
3941 <tt>/usr/local</tt>, not <em>in</em>
3942 <tt>/usr/local</tt>. Packages must not create sub-directories
3943 in the directory <tt>/usr/local</tt> itself, except those listed in
3944 FHS, section 4.5. However, you may create directories
3945 below them as you wish. You must not remove any of the
3946 directories listed in 4.5, even if you created them.</p>
3949 Since <tt>/usr/local</tt> can be mounted read-only from a
3950 remote server, these directories must be created and
3951 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3952 maintainer scripts. These scripts must not fail if either
3953 of these operations fail. (In the future, it will be
3954 possible to tell <prgn>dpkg</prgn> not to unpack files
3955 matching certain patterns, so that the directories can be
3956 included in the <tt>.deb</tt> packages and system
3957 administrators who do not wish these directories in
3958 /usr/local do not need to have them.)</p>
3961 For example, the <prgn>emacs</prgn> package will contain
3963 mkdir -p /usr/local/lib/emacs/site-lisp || true
3965 in the <tt>postinst</tt> script, and
3967 rmdir /usr/local/lib/emacs/site-lisp || true
3968 rmdir /usr/local/lib/emacs || true
3970 in the <tt>prerm</tt> script.</p>
3973 If you do create a directory in <tt>/usr/local</tt> for
3974 local additions to a package, you should ensure that
3975 settings in <tt>/usr/local</tt> take precedence over the
3976 equivalents in <tt>/usr</tt>.</p>
3979 However, because '/usr/local' and its contents are for
3980 exclusive use of the local administrator, a package must
3981 not rely on the presence or absence of files or
3982 directories in '/usr/local' for normal operation.</p>
3985 The <tt>/usr/local</tt> directory itself and all the
3986 subdirectories created by the package should (by default) have
3987 permissions 2775 (group-writable and set-group-id) and be
3988 owned by <tt>root.staff</tt>.</p>
3993 <heading>Users and groups</heading>
3996 The Debian system can be configured to use either plain or
3997 shadow passwords.</p>
4000 Some user ids (UIDs) and group ids (GIDs) are reserved
4001 globally for use by certain packages. Because some packages
4002 need to include files which are owned by these users or
4003 groups, or need the ids compiled into binaries, these ids
4004 must be used on any Debian system only for the purpose for
4005 which they are allocated. This is a serious restriction, and
4006 we should avoid getting in the way of local administration
4007 policies. In particular, many sites allocate users and/or
4008 local system groups starting at 100.</p>
4011 Apart from this we should have dynamically allocated ids,
4012 which should by default be arranged in some sensible
4013 order--but the behavior should be configurable.</p>
4016 Packages other than <tt>base-passwd</tt> must not modify
4017 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4018 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4021 The UID and GID ranges are as follows:
4026 Globally allocated by the Debian project, the
4027 same on every Debian system. These ids will appear in
4028 the <tt>passwd</tt> and <tt>group</tt> files of all
4029 Debian systems, new ids in this range being added
4030 automatically as the <tt>base-passwd</tt> package is
4034 Packages which need a single statically allocated uid
4035 or gid should use one of these; their maintainers
4036 should ask the <tt>base-passwd</tt> maintainer for
4043 Dynamically allocated system users and groups.
4044 Packages which need a user or group, but can have this
4045 user or group allocated dynamically and differently on
4046 each system, should use `<tt>adduser --system</tt>' to
4047 create the group and/or user. <prgn>adduser</prgn>
4048 will check for the existence of the user or group, and
4049 if necessary choose an unused id based on the ranges
4050 specified in <tt>adduser.conf</tt>.</p></item>
4053 <tag>1000-29999:</tag>
4056 Dynamically allocated user accounts. By default
4057 <prgn>adduser</prgn> will choose UIDs and GIDs for
4058 user accounts in this range, though
4059 <tt>adduser.conf</tt> may be used to modify this
4063 <tag>30000-59999:</tag>
4065 <p>Reserved.</p></item>
4068 <tag>60000-64999:</tag>
4071 Globally allocated by the Debian project, but only
4072 created on demand. The ids are allocated centrally and
4073 statically, but the actual accounts are only created
4074 on users' systems on demand.</p>
4077 These ids are for packages which are obscure or which
4078 require many statically-allocated ids. These packages
4079 should check for and create the accounts in
4080 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4081 <prgn>adduser</prgn> if it has this facility) if
4082 necessary. Packages which are likely to require
4083 further allocations should have a `hole' left after
4084 them in the allocation, to give them room to
4088 <tag>65000-65533:</tag>
4090 <p>Reserved.</p></item>
4095 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4096 to the group `<tt>nogroup</tt>.'</p></item>
4102 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4103 because it is the error return sentinel value.</p>
4108 <sect id="sysvinit">
4109 <heading>System run levels</heading>
4112 <sect1 id="/etc/init.d">
4113 <heading>Introduction</heading>
4116 The <tt>/etc/init.d</tt> directory contains the scripts
4117 executed by <prgn>init</prgn> at boot time and when init
4118 state (or `runlevel') is changed (see <manref name="init"
4122 There are at least two different, yet functionally
4123 equivalent, ways of handling these scripts. For the sake
4124 of simplicity, this document describes only the symbolic
4125 link method. However, it must not be assumed by maintainer
4126 scripts that this method is being used, and any automated
4127 manipulation of the various runlevel behaviours by
4128 maintainer scripts must be performed using `update-rc.d'
4129 as described below and not by manually installing or
4130 removing symlinks. For information on the
4131 implementation details of the other method, implemented in
4132 the <tt>file-rc</tt> package, please refer to the
4133 documentation of that package.</p>
4136 These scripts are referenced by symbolic links in
4137 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4138 changing runlevels, <prgn>init</prgn> looks in the
4139 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4140 it should execute, where <var>n</var> is the runlevel that
4141 is being changed to, or `S' for the boot-up scripts.</p>
4144 The names of the links all have the form
4145 <tt>S<var>mm</var><var>script</var></tt> or
4146 <tt>K<var>mm</var><var>script</var></tt> where
4147 <var>mm</var> is a two-digit number and <var>script</var>
4148 is the name of the script (this should be the same as the
4149 name of the actual script in <tt>/etc/init.d</tt>.</p>
4152 When <prgn>init</prgn> changes runlevel first the targets
4153 of the links whose names starting with a <tt>K</tt> are
4154 executed, each with the single argument <tt>stop</tt>,
4155 followed by the scripts prefixed with an <tt>S</tt>, each
4156 with the single argument <tt>start</tt>. The <tt>K</tt>
4157 links are responsible for killing services and the
4158 <tt>S</tt> link for starting services upon entering the
4162 For example, if we are changing from runlevel 2 to
4163 runlevel 3, init will first execute all of the <tt>K</tt>
4164 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4165 all of the <tt>S</tt> prefixed scripts. The links
4166 starting with <tt>K</tt> will cause the referred-to file
4167 to be executed with an argument of <tt>stop</tt>, and the
4168 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4171 The two-digit number <var>mm</var> is used to decide which
4172 order to start and stop things in--low-numbered links have
4173 their scripts run first. For example, the <tt>K20</tt>
4174 scripts will be executed before the <tt>K30</tt> scripts.
4175 This is used when a certain service must be started before
4176 another. For example, the name server <prgn>bind</prgn>
4177 might need to be started before the news server
4178 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4179 access lists. In this case, the script that starts
4180 <prgn>bind</prgn> would have a lower number than the
4181 script that starts <prgn>inn</prgn> so that it runs first:
4190 <heading>Writing the scripts</heading>
4193 Packages that include daemons for system services should
4194 place scripts in <tt>/etc/init.d</tt> to start or stop
4195 services at boot time or during a change of runlevel.
4196 These scripts should be named
4197 <tt>/etc/init.d/<var>package</var></tt>, and they should
4198 accept one argument, saying what to do:
4201 <tag><tt>start</tt></tag>
4202 <item><p>start the service,</p></item>
4204 <tag><tt>stop</tt></tag>
4205 <item><p>stop the service,</p></item>
4207 <tag><tt>restart</tt></tag>
4208 <item><p>stop and restart the service,</p></item>
4210 <tag><tt>reload</tt></tag>
4211 <item><p>cause the configuration of the service to be
4212 reloaded without actually stopping and restarting
4213 the service,</p></item>
4215 <tag><tt>force-reload</tt></tag> <item><p>cause the
4216 configuration to be reloaded if the service supports
4217 this, otherwise restart the service.</p></item>
4220 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4221 <tt>force-reload</tt> options should be supported by all
4222 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4223 option is optional.</p>
4226 The <tt>init.d</tt> scripts should ensure that they will
4227 behave sensibly if invoked with <tt>start</tt> when the
4228 service is already running, or with <tt>stop</tt> when it
4229 isn't, and that they don't kill unfortunately-named user
4230 processes. The best way to achieve this is usually to use
4231 <prgn>start-stop-daemon</prgn>.</p>
4234 If a service reloads its configuration automatically (as
4235 in the case of <prgn>cron</prgn>, for example), the
4236 <tt>reload</tt> option of the <tt>init.d</tt> script
4237 should behave as if the configuration has been reloaded
4241 These scripts should not fail obscurely when the
4242 configuration files remain but the package has been
4243 removed, as configuration files remain on the system after
4244 the package has been removed. Only when <prgn>dpkg</prgn>
4245 is executed with the <tt>--purge</tt> option will
4246 configuration files be removed. In particular, the init
4247 script itself is usually a configuration file (see
4248 <ref id="init.d notes">), and will remain on the system if
4249 the package is removed but not purged. Therefore, you
4250 should include a <tt>test</tt> statement at the top of the
4253 test -f <var>program-executed-later-in-script</var> || exit 0
4257 Often there are some values in the `<tt>init.d</tt>'
4258 scripts that a system administrator will frequently want
4259 to change. While the scripts are frequently conffiles,
4260 modifying them requires that the administrator merge in
4261 their changes each time the package is upgraded and the
4262 conffile changes. To ease the burden on the system
4263 administrator, such configurable values should not be
4264 placed directly in the script. Instead, they should be
4265 placed in a file in `<tt>/etc/default</tt>', which
4266 typically will have the same base name as the
4267 `<tt>init.d</tt>' script. This extra file can be sourced
4268 by the script when the script runs. It must contain only
4269 variable settings and comments.
4273 To ensure that vital configurable values are always
4274 available, the `<tt>init.d</tt>' script should set default
4275 values for each of the shell variables it uses before
4276 sourcing the <tt>/etc/default/</tt> file. Also, since the
4277 `<tt>/etc/default/</tt>' file is often a conffile, the
4278 `<tt>init.d</tt>' script must behave sensibly without
4279 failing if it is deleted.
4285 <heading>Managing the links</heading>
4288 The program <prgn>update-rc.d</prgn> is provided to make
4289 it easier for package maintainers to arrange for the
4290 proper creation and removal of
4291 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4292 functional equivalent if another method is being used.
4293 This may be used by maintainers in their packages'
4294 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4297 You must use this script to make changes to
4298 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4299 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4300 in the actual archive or manually create or remove the
4301 symbolic links in maintainer scripts. (The latter will
4302 fail if an alternative method of maintaining runlevel
4303 information is being used.)</p>
4306 By default <prgn>update-rc.d</prgn> will start services in
4307 each of the multi-user state runlevels (2, 3, 4, and 5)
4308 and stop them in the halt runlevel (0), the single-user
4309 runlevel (1) and the reboot runlevel (6). The system
4310 administrator will have the opportunity to customize
4311 runlevels by either running <prgn>update-rc.d</prgn>, by
4312 simply adding, moving, or removing the symbolic links in
4313 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4314 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4315 <tt>file-rc</tt> method is being used.</p>
4318 To get the default behavior for your package, put in your
4319 <tt>postinst</tt> script
4321 update-rc.d <var>package</var> defaults >/dev/null
4323 and in your <tt>postrm</tt>
4325 if [ purge = "$1" ]; then
4326 update-rc.d <var>package</var> remove >/dev/null
4331 This will use a default sequence number of 20. If it does
4332 not matter when or in which order the script is run, use
4333 this default. If it does, then you should talk to the
4334 maintainer of the <prgn>sysvinit</prgn> package or post to
4335 <tt>debian-devel</tt>, and they will help you choose a
4339 For more information about using <tt>update-rc.d</tt>,
4340 please consult its manpage <manref name="update-rc.d"
4341 section="8">.</p></sect1>
4345 <heading>Boot-time initialization</heading>
4348 There used to be another directory, <tt>/etc/rc.boot</tt>,
4349 which contained scripts which were run once per machine
4350 boot. This has been deprecated in favour of links from
4351 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4352 described in <ref id="/etc/init.d">. Packages must not
4353 place files in <tt>/etc/rc.boot</tt>.</p>
4355 <sect1 id="init.d notes">
4356 <heading>Notes</heading>
4359 <em>Do not</em> include the
4360 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4361 <tt>.deb</tt> file system archive! <em>This will cause
4362 problems!</em> You must create them with
4363 <prgn>update-rc.d</prgn>, as above.</p>
4366 <em>Do not</em> include the
4367 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4368 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4369 problems!</em> You should, however, treat the
4370 <tt>/etc/init.d</tt> scripts as configuration files,
4371 either by marking them as conffiles or managing them
4372 correctly in the maintainer scripts (see
4373 <ref id="config files">). (This is important since we want
4374 to give the local system administrator the chance to adapt
4375 the scripts to the local system--e.g., to disable a
4376 service without de-installing the package, or to specify
4377 some special command line options when starting a
4378 service--while making sure her changes aren't lost during
4379 the next package upgrade.)</p>
4383 <heading>Example</heading>
4386 The <prgn>bind</prgn> DNS (nameserver) package wants to
4387 make sure that the nameserver is running in multiuser
4388 runlevels, and is properly shut down with the system. It
4389 puts a script in <tt>/etc/init.d</tt>, naming the script
4390 appropriately <tt>bind</tt>. As you can see, the script
4391 interprets the argument <tt>reload</tt> to send the
4392 nameserver a <tt>HUP</tt> signal (causing it to reload its
4393 configuration); this way the user can say
4394 <tt>/etc/init.d/bind reload</tt> to reload the name
4395 server. The script has one configurable value, which can
4396 be used to pass parameters to the named program at
4404 # Original version by Robert Leslie
4405 # <rob@mars.org>, edited by iwj and cs
4407 test -x /usr/sbin/named || exit 0
4409 # Source defaults file.
4411 if [ -f /etc/default/bind ]; then
4418 echo -n "Starting domain name service: named"
4419 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4424 echo -n "Stopping domain name service: named"
4425 start-stop-daemon --stop --quiet \
4426 --pidfile /var/run/named.pid --exec /usr/sbin/named
4430 echo -n "Restarting domain name service: named"
4431 start-stop-daemon --stop --quiet \
4432 --pidfile /var/run/named.pid --exec /usr/sbin/named
4433 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4437 force-reload|reload)
4438 echo -n "Reloading configuration of domain name service: named"
4439 start-stop-daemon --stop --signal 1 --quiet \
4440 --pidfile /var/run/named.pid --exec /usr/sbin/named
4444 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4454 Complementing the above init script is a file
4455 '<tt>/etc/default/bind</tt>', which contains configurable
4456 parameters used by the script.
4460 # Specified parameters to pass to named. See named(8).
4461 # You may uncomment the following line, and edit to taste.
4467 Another example on which to base your <tt>/etc/init.d</tt>
4468 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4471 If this package is happy with the default setup from
4472 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4473 and having named running in all runlevels, it can say in
4474 its <tt>postinst</tt>:
4476 update-rc.d bind defaults >/dev/null
4478 And in its <tt>postrm</tt>, to remove the links when the
4481 if [ purge = "$1" ]; then
4482 update-rc.d bind remove >/dev/null
4488 <heading>Cron jobs</heading>
4491 Packages must not modify the configuration file
4492 <tt>/etc/crontab</tt>, and they must not modify the files in
4493 <tt>/var/spool/cron/crontabs</tt>.</p>
4496 If a package wants to install a job that has to be executed
4497 via cron, it should place a file with the name of the
4498 package in one of the following directories:
4504 As these directory names imply, the files within them are
4505 executed on a daily, weekly, or monthly basis,
4506 respectively. The exact times are listed in
4507 <tt>/etc/crontab</tt>.</p>
4510 All files installed in any of these directories must be
4511 scripts (shell scripts, Perl scripts, etc.) so that they can
4512 easily be modified by the local system administrator. In
4513 addition, they should be treated as configuration files.</p>
4516 If a certain job has to be executed more frequently than
4517 daily, the package should install a file
4518 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4519 the same syntax as <tt>/etc/crontab</tt> and is processed by
4520 <prgn>cron</prgn> automatically. The file must also be
4521 treated as a configuration file. (Note, that entries in the
4522 <tt>/etc/cron.d</tt> directory are not handled by
4523 <prgn>anacron</prgn>. Thus, you should only use this
4524 directory for jobs which may be skipped if the system is not
4528 The scripts or crontab entries in these directories should
4529 check if all necessary programs are installed before they
4530 try to execute them. Otherwise, problems will arise when a
4531 package was removed but not purged since configuration files
4532 are kept on the system in this situation.</p>
4536 <heading>Console messages</heading>
4539 This section describes different formats for messages
4540 written to standard output by the <tt>/etc/init.d</tt>
4541 scripts. The intent is to improve the consistency of
4542 Debian's startup and shutdown look and feel.</p>
4545 Please look very careful at the details. We want to get the
4546 messages to look exactly the same way concerning spaces,
4547 punctuation, and case of letters.</p>
4550 Here is a list of overall rules that you should use when you
4551 create output messages. They can be useful if you have a
4552 non-standard message that isn't covered in the sections
4559 Every message should cover one line, start with a
4560 capital letter and end with a period `.'.</p></item>
4565 If you want to express that the computer is working on
4566 something (performing a specific task, not starting or
4567 stopping a program), we use an ``ellipsis'', namely
4568 three dots `...'. Note that we don't insert spaces in
4569 front of or behind the dots. If the task has been
4570 completed we write `done.' and a line feed.</p></item>
4575 Design your messages as if the computer is telling you
4576 what he is doing (let him be polite :-) but don't
4577 mention ``him'' directly. For example, if you think
4580 I'm starting network daemons: nfsd mountd.
4584 Starting network daemons: nfsd mountd.
4585 </example></p></item>
4589 The following formats should be used</p>
4594 <p>when daemons get started.</p>
4597 Use this format if your script starts one or more
4598 daemons. The output should look like this (a single
4599 line, no leading spaces):
4601 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4603 The <description> should describe the subsystem
4604 the daemon or set of daemons are part of, while
4605 <daemon-1> up to <daemon-n> denote each
4606 daemon's name (typically the file name of the
4610 For example, the output of /etc/init.d/lpd would look like:
4612 Starting printer spooler: lpd.
4616 This can be achieved by saying
4618 echo -n "Starting printer spooler: lpd"
4619 start-stop-daemon --start --quiet lpd
4622 in the script. If you have more than one daemon to
4623 start, you should do the following:
4625 echo -n "Starting remote file system services:"
4626 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4627 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4628 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4631 This makes it possible for the user to see what takes
4632 so long and when the final daemon has been
4633 started. You should be careful where to put spaces: In the
4634 example above the system administrator can easily
4635 comment out a line if he don't wants to start a
4636 specific daemon, while the displayed message still
4637 looks good.</p></item>
4641 <p>when something needs to be configured.</p>
4644 If you have to set up different parameters of the
4645 system upon boot up, you should use this format:
4647 Setting <parameter> to `<value>'.
4651 You can use the following echo statement to get the quotes right:
4653 echo "Setting DNS domainname to \`"value"'."
4657 Note that the left quotation mark (`) is different
4658 from the right (').</p></item>
4661 <p>when a daemon is stopped.</p>
4664 When you stop a daemon you should issue a message
4665 similar to the startup message, except that `Starting'
4666 is replaced with `Stopping'.</p>
4669 So stopping the printer daemon will like like this:
4671 Stopping printer spooler: lpd.
4672 </example></p></item>
4675 <p>when something is executed.</p>
4678 There are several examples where you have to run a
4679 program at system startup or shutdown to perform a
4680 specific task. For example, setting the system's clock
4681 via `netdate' or killing all processes when the system
4682 comes down. Your message should like this:
4684 Doing something very useful...done.
4686 You should print the `done.' right after the job has been completed,
4687 so that the user gets informed why he has to wait. You can get this
4690 echo -n "Doing something very useful..."
4694 in your script.</p></item>
4697 <p>when the configuration is reloaded.</p>
4700 When a daemon is forced to reload its configuration
4701 files you should use the following format:
4703 Reloading <daemon's-name> configuration...done.
4704 </example></p></item>
4707 <p>when none of the above rules apply.</p>
4710 If you have to print a message that doesn't fit into
4711 the styles described above, you can use something
4712 appropriate, but please have a look at the overall
4713 rules listed above.</p></item>
4718 <heading>Menus</heading>
4721 Menu entries should follow the current menu policy as
4722 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4723 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4724 or your local mirror. In addition, it is included in the
4725 <tt>debian-policy</tt> package.
4729 The Debian <tt>menu</tt> packages provides a unique
4730 interface between packages providing applications and
4731 documents, and <em>menu programs</em> (either X window
4732 managers or text-based menu programs as
4733 <prgn>pdmenu</prgn>).</p>
4736 All packages that provide applications that need not be
4737 passed any special command line arguments for normal
4738 operation should register a menu entry for those
4739 applications, so that users of the <tt>menu</tt> package
4740 will automatically get menu entries in their window
4741 managers, as well in shells like <tt>pdmenu</tt>.</p>
4744 Please refer to the <em>Debian Menu System</em> document
4745 that comes with the <tt>menu</tt> package for information
4746 about how to register your applications and web
4752 <heading>Multimedia handlers</heading>
4755 Packages which provide the ability to view/show/play,
4756 compose, edit or print MIME types should register themselves
4757 as such following the current MIME support policy as defined
4758 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4759 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4760 or your local mirror. In addition, it is included in the
4761 <tt>debian-policy</tt> package.
4765 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4766 mechanism for encoding files and data streams and providing
4767 meta-information about them, in particular their type (e.g.
4768 audio or video) and format (e.g. PNG, HTML, MP3).
4772 Registration of MIME type handlers allows programs like mail
4773 user agents and web browsers to to invoke these handlers to
4774 view, edit or display MIME types they don't support
4780 <heading>Keyboard configuration</heading>
4783 To achieve a consistent keyboard configuration (i.e., all
4784 applications interpret a keyboard event the same way) all
4785 programs in the Debian distribution must be configured to
4786 comply with the following guidelines.</p>
4789 Here is a list that contains certain keys and their interpretation:
4792 <tag><tt><--</tt></tag>
4793 <item><p>delete the character to the left of the cursor</p></item>
4795 <tag><tt>Delete</tt></tag>
4796 <item><p>delete the character to the right of the cursor</p></item>
4798 <tag><tt>Control+H</tt></tag>
4799 <item><p>emacs: the help prefix</p></item>
4802 The interpretation of any keyboard events should be independent
4803 of the terminal that's used, be it a virtual console, an X
4804 terminal emulator, an rlogin/telnet session, etc.</p>
4807 The following list explains how the different programs
4808 should be set up to achieve this:</p>
4811 <list compact="compact">
4812 <item><p>`<tt><--</tt>' generates KB_Backspace in
4815 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4819 X translations are set up to make KB_Backspace
4820 generate ASCII DEL, and to make KB_Delete generate
4821 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4822 the `delete character' key). This must be done by
4823 loading the resources using xrdb on all local X
4824 displays, not using the application defaults, so that
4825 the translation resources used correspond to the
4826 xmodmap settings.</p></item>
4830 The Linux console is configured to make
4831 `<tt><--</tt>' generate DEL, and `Delete' generate
4832 <tt>ESC [ 3 ~</tt> (this is the case at the
4836 X applications are configured so that Backspace
4837 deletes left, and Delete deletes right. Motif
4838 applications already work like this.</p></item>
4840 <item><p>stty erase <tt>^?</tt> .</p></item>
4843 The `xterm' terminfo entry should have <tt>ESC [ 3
4844 ~</tt> for kdch1, just like TERM=linux and
4845 TERM=vt220.</p></item>
4848 Emacs is programmed to map KB_Backspace or the `stty
4849 erase' character to delete-backward-char, and
4850 KB_Delete or kdch1 to delete-forward-char, and
4851 <tt>^H</tt> to help as always.</p></item>
4854 Other applications use the `stty erase' character and
4855 kdch1 for the two delete keys, with ASCII DEL being
4856 `delete previous character' and kdch1 being `delete
4857 character under cursor'.</p></item>
4861 This will solve the problem except for:</p>
4864 <list compact="compact">
4866 Some terminals have a <tt><--</tt> key that cannot
4867 be made to produce anything except <tt>^H</tt>. On
4868 these terminals Emacs help will be unavailable on
4869 <tt>^H</tt> (assuming that the `stty erase' character
4870 takes precedence in Emacs, and has been set
4871 correctly). M-x help or F1 (if available) can be used
4875 Some operating systems use <tt>^H</tt> for stty erase.
4876 However, modern telnet versions and all rlogin
4877 versions propagate stty settings, and almost all UNIX
4878 versions honour stty erase. Where the stty settings
4879 are not propagated correctly things can be made to
4880 work by using stty manually.</p></item>
4883 Some systems (including previous Debian versions) use
4884 xmodmap to arrange for both <tt><--</tt> and Delete
4885 to generate KB_Delete. We can change the behavior
4886 of their X clients via the same X resources that we
4887 use to do it for our own, or have our clients be
4888 configured via their resources when things are the
4889 other way around. On displays configured like this
4890 Delete will not work, but <tt><--</tt>
4894 Some operating systems have different kdch1 settings
4895 in their terminfo for xterm and others. On these
4896 systems the Delete key will not work correctly when
4897 you log in from a system conforming to our policy, but
4898 <tt><--</tt> will.</p></item>
4905 <heading>Environment variables</heading>
4908 A program must not depend on environment variables to get
4909 reasonable defaults. (That's because these environment
4910 variables would have to be set in a system-wide
4911 configuration file like /etc/profile, which is not supported
4915 If a program usually depends on environment variables for its
4916 configuration, the program should be changed to fall back to
4917 a reasonable default configuration if these environment
4918 variables are not present. If this cannot be done easily
4919 (e.g., if the source code of a non-free program is not
4920 available), the program must be replaced by a small
4921 `wrapper' shell script which sets the environment variables
4922 if they are not already defined, and calls the original program.</p>
4925 Here is an example of a wrapper script for this purpose:
4929 BAR=${BAR:-/var/lib/fubar}
4931 exec /usr/lib/foo/foo "$@"
4935 Furthermore, as <tt>/etc/profile</tt> is a configuration
4936 file of the <prgn>base-files</prgn> package, other packages must not
4937 put any environment variables or other commands into that
4942 <heading>Files</heading>
4946 <heading>Binaries</heading>
4949 Two different packages must not install programs with
4950 different functionality but with the same filenames. (The
4951 case of two programs having the same functionality but
4952 different implementations is handled via `alternatives.')
4953 If this case happens, one of the programs must be
4954 renamed. The maintainers should report this to the
4955 developers' mailing and try to find a consensus about
4956 which package will have to be renamed. If a consensus can
4957 not be reached, <em>both</em> programs must be
4961 Generally the following compilation parameters should be used:
4964 CFLAGS = -O2 -Wall # sane warning options vary between programs
4966 install -s # (or use strip on the files in debian/tmp)
4970 Note that by default all installed binaries should be stripped,
4971 either by using the <tt>-s</tt> flag to
4972 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4973 the binaries after they have been copied into
4974 <tt>debian/tmp</tt> but before the tree is made into a
4978 The <tt>-N</tt> flag should not be used. On a.out systems
4979 it may have been useful for some very small binaries, but
4980 for ELF it has no good effect.</p>
4983 Debugging symbols are useful for error diagnosis,
4984 investigation of core dumps (which may be submitted by users
4985 in bug reports), or testing and developing the
4986 software. Therefore it is recommended to support building
4987 the package with debugging information through the following
4988 interface: If the environment variable
4989 <tt>DEB_BUILD_OPTIONS</tt> contains the string
4990 <tt>debug</tt>, compile the software with debugging
4991 information (usually this involves adding the <tt>-g</tt>
4992 flag to <tt>CFLAGS</tt>). This allows the generation of a
4993 build tree with debugging information. If the environment
4994 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
4995 <tt>nostrip</tt>, do not strip the files at installation
4996 time. This allows one to generate a package with debugging
4997 information included. The following makefile snippet is only
4998 an example of how one may test for either condition:
5001 Rationale: Building by default with -g causes more
5002 wasted CPU cycles since the information is stripped away
5003 anyway. The package can by default build without -g if
5004 it also provides a mechanism to easily be rebuilt with
5005 debugging information. This can be done by providing a
5006 "build-debug" make target, or allowing the user to
5007 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5008 compiling that package.
5010 <p>Now this has several added benefits:
5014 It is actually easier to build debugging bins and
5015 libraries this way (no more editing debian/rules
5016 or similar) since it provides a documented way of
5017 getting this type of build.</p>
5021 There will be much less wasted CPU time for the
5022 autobuilders since not having debugging
5023 information (and hence also not having to strip
5024 it) will increase the speed of compiles. This
5025 skips an entire pass of the compiler.
5036 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5037 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5038 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5039 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5041 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5044 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5045 INSTALL_PROGRAM += -s
5049 Please note that the above example is merely informative,
5050 and is not a policy mandate. You may have to massage this
5051 example in order to make it work for your package.
5056 It is up to the package maintainer to decide what
5057 compilation options are best for the package. Certain
5058 binaries (such as computationally-intensive programs) will
5059 function better with certain flags (<tt>-O3</tt>, for
5060 example); feel free to use them. Please use good judgment
5061 here. Don't use flags for the sake of it; only use them
5062 if there is good reason to do so. Feel free to override
5063 the upstream author's ideas about which compilation
5064 options are best--they are often inappropriate for our
5065 environment.</p></sect>
5069 <heading>Libraries</heading>
5072 All libraries must have a shared version in the lib
5073 package and a static version in the lib-dev package. The
5074 shared version must be compiled with <tt>-fPIC</tt>, and
5075 the static version must not be. In other words, each
5076 <tt>*.c</tt> file will need to be compiled twice.</p>
5079 You must specify the gcc option <tt>-D_REENTRANT</tt>
5080 when building a library (either static or shared) to make
5081 the library compatible with LinuxThreads.</p>
5084 Note that all installed shared libraries should be
5087 strip --strip-unneeded <your-lib>
5089 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5090 only the symbols which aren't needed for relocation
5091 processing.) Shared libraries can function perfectly well
5092 when stripped, since the symbols for dynamic linking are
5093 in a separate part of the ELF object file.</p>
5096 Note that under some circumstances it may be useful to
5097 install a shared library unstripped, for example when
5098 building a separate package to support debugging.
5102 An ever increasing number of packages are using libtool to
5103 do their linking. The latest GNU libtools (>= 1.3a) can take
5104 advantage of the metadata in the installed libtool archive
5105 files (`*.la'). The main advantage of libtool's .la files is
5106 that it allows libtool to store and subsequently access
5107 metadata with respect to the libraries it builds. libtool
5108 will search for those files, which contain a lot of useful
5109 information about a library (e.g. dependency libraries for
5110 static linking). Also, they're <em>essential</em> for
5111 programs using libltdl.
5115 Certainly libtool is fully capable of linking against shared
5116 libraries which don't have .la files, but being a mere shell
5117 script it can add considerably to the build time of a
5118 libtool using package if that shell-script has to derive all
5119 this information from first principles for each library every
5120 time it is linked. With the advent of libtool-1.4 (and to a
5121 lesser extent libtool-1.3), the .la files will also store
5122 information about inter-library dependencies which cannot
5123 necessarily be derived after the .la file is deleted.
5127 Packages that use libtool to create shared libraries should
5128 include the <em>.la</em> files in the <em>-dev</em>
5129 packages, with the exception that if the package relies on
5130 libtool's <em>libltdl</em> library, in which case the .la
5131 files must go in the run-time library package. This is a
5132 good idea in general, and especially for static linking
5137 You must make sure that you use only released versions of
5138 shared libraries to build your packages; otherwise other
5139 users will not be able to run your binaries
5140 properly. Producing source packages that depend on
5141 unreleased compilers is also usually a bad
5148 <heading>Shared libraries</heading>
5151 Packages involving shared libraries should be split up
5152 into several binary packages.</p>
5155 For a straightforward library which has a development
5156 environment and a runtime kit including just shared
5157 libraries you need to create two packages:
5158 <tt><var>libraryname</var><var>soname</var></tt>
5159 (<var>soname</var> is the shared object name of the shared
5160 library--it's the thing that has to match exactly between
5161 building an executable and running it for the dynamic
5162 linker to be able run the program; usually the
5163 <var>soname</var> is the major number of the library) and
5164 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5167 If you prefer only to support one development version at a
5168 time you may name the development package
5169 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5170 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5171 ensure that the user only installs one development version
5172 at a time (after all, different development versions are
5173 likely to have the same header files in them, causing a
5174 filename clash if both are installed). Typically the
5175 development version should also have an exact version
5176 dependency on the runtime library, to make sure that
5177 compilation and linking happens correctly.</p>
5180 Packages which use the shared library should have a
5181 dependency on the name of the shared library package,
5182 <tt><var>libraryname</var><var>soname</var></tt>. When
5183 the <var>soname</var> changes you can have both versions
5184 of the library installed while moving from the old library
5188 If your package has some run-time support programs which
5189 use the shared library you must not put them in
5190 the shared library package. If you do that then you won't
5191 be able to install several versions of the shared library
5192 without getting filename clashes. Instead, either create
5193 a third package for the runtime binaries (this package
5194 might typically be named
5195 <tt><var>libraryname</var>-runtime</tt>--note the absence
5196 of the <var>soname</var> in the package name) or if the
5197 development package is small include them in there.</p>
5200 If you have several shared libraries built from the same
5201 source tree you may lump them all together into a single
5202 shared library package, provided that you change all their
5203 <var>soname</var>s at once (so that you don't get filename
5204 clashes if you try to install different versions of the
5205 combined shared libraries package).</p>
5208 You should follow the directions in the <em>Debian Packaging
5209 Manual</em> for putting the shared library in its package,
5210 and you must include a <tt>shlibs</tt> control area
5211 file with details of the dependencies for packages which
5212 use the library.</p>
5215 Shared libraries should not be installed
5216 executable, since <prgn>ld.so</prgn> does not require this
5217 and trying to execute a shared library results in a core
5222 <heading>Scripts</heading>
5225 All command scripts, including the package maintainer
5226 scripts inside the package and used by <prgn>dpkg</prgn>,
5227 should have a <tt>#!</tt> line naming the shell to be used
5228 to interpret them.</p>
5231 In the case of Perl scripts this should be
5232 <tt>#!/usr/bin/perl</tt>.</p>
5235 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5236 should almost certainly start with <tt>set -e</tt> so that
5237 errors are detected. Every script should use
5238 <tt>set -e</tt> or check the exit status of <em>every</em>
5242 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5243 symbolic link to any POSIX compatible shell, if <tt>echo
5244 -n</tt> does not generate a newline.
5247 Debian policy specifies POSIX behavior for /bin/sh, but
5248 echo -n has widespread use in the Linux community
5249 (including especially debian policy, the linux kernel
5250 source, many debian scripts, etc.). This echo -n
5251 mechanism is valid but not required under POSIX, hence
5252 this explicit addition. Also, rumour has it that this
5253 shall be mandated under the LSB anyway.
5257 specifying `<tt>/bin/sh</tt>' as interpreter should only
5258 use POSIX features. If a script requires non-POSIX
5259 features from the shell interpreter, the appropriate shell
5260 must be specified in the first line of the script (e.g.,
5261 `<tt>#!/bin/bash</tt>') and the package must depend on the
5262 package providing the shell (unless the shell package is
5263 marked `Essential', e.g., in the case of
5268 You may wish to restrict your script to POSIX features when possible so
5269 that it may use <tt>/bin/sh</tt> as its interpreter. If
5270 your script works with <prgn>ash</prgn>, it's probably
5271 POSIX compliant, but if you are in doubt, use
5272 <tt>/bin/bash</tt>.</p>
5275 Perl scripts should check for errors when making any
5276 system calls, including <tt>open</tt>, <tt>print</tt>,
5277 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5280 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5281 as scripting languages. See <em>Csh Programming
5282 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5283 FAQs. It can be found on
5284 <url id="http://language.perl.com/versus/csh.whynot">, or
5285 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5286 or even on <ftpsite>ftp.cpan.org</ftpsite>
5287 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5288 If an upstream package comes with <prgn>csh</prgn> scripts
5289 then you must make sure that they start with
5290 <tt>#!/bin/csh</tt> and make your package depend on the
5291 <prgn>c-shell</prgn> virtual package.</p>
5294 Any scripts which create files in world-writeable
5295 directories (e.g., in <tt>/tmp</tt>) must use a
5296 mechanism which will fail if a file with the same name
5300 The Debian base distribution provides the
5301 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5302 for use by scripts for this purpose.</p></sect>
5306 <heading>Symbolic links</heading>
5309 In general, symbolic links within a top-level directory
5310 should be relative, and symbolic links pointing from one
5311 top-level directory into another should be absolute. (A
5312 top-level directory is a sub-directory of the root
5316 In addition, symbolic links should be specified as short
5317 as possible, i.e., link targets like `foo/../bar' are
5321 Note that when creating a relative link using
5322 <prgn>ln</prgn> it is not necessary for the target of the
5323 link to exist relative to the working directory you're
5324 running <prgn>ln</prgn> from; nor is it necessary to
5325 change directory to the directory where the link is to be
5326 made. Simply include the string that should appear as the
5327 target of the link (this will be a pathname relative to
5328 the directory in which the link resides) as the first
5329 argument to <prgn>ln</prgn>.</p>
5332 For example, in your <prgn>Makefile</prgn> or
5333 <tt>debian/rules</tt>, do things like:
5335 ln -fs gcc $(prefix)/bin/cc
5336 ln -fs gcc debian/tmp/usr/bin/cc
5337 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5338 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5342 A symbolic link pointing to a compressed file should
5343 always have the same file extension as the referenced
5344 file. (For example, if a file `<tt>foo.gz</tt>' is
5345 referenced by a symbolic link, the filename of the link
5346 has to end with `<tt>.gz</tt>' too, as in
5347 `bar.gz.')</p></sect>
5351 <heading>Device files</heading>
5354 Packages must not include device files in the package file
5358 If a package needs any special device files that are not
5359 included in the base system, it must call
5360 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5361 after asking the user for permission to do so.</p>
5364 Packages must not remove any device files in the
5365 <tt>postrm</tt> or any other script. This is left to the
5366 system administrator.</p>
5369 Debian uses the serial devices
5370 <tt>/dev/ttyS*</tt>. Programs using the old
5371 <tt>/dev/cu*</tt> devices should be changed to use
5372 <tt>/dev/ttyS*</tt>.</p>
5375 <sect id="config files">
5376 <heading>Configuration files</heading>
5378 <heading>Definitions</heading>
5381 <tag>configuration file</tag>
5383 A file that affects the operation of program, or
5384 provides site- or host-specific information, or
5385 otherwise customizes the behavior of program.
5386 Typically, configuration files are intended to be
5387 modified by the system administrator (if needed or
5388 desired) to conform to local policy or provide more
5389 useful site-specific behavior.</p>
5392 <tag><tt>conffile</tt></tag>
5394 A file listed in a package's <tt>conffiles</tt>
5395 file, and is treated specially by <prgn>dpkg</prgn>
5396 (see the <em>Debian Packaging Manual</em>).</p>
5402 The distinction between these two is important; they are
5403 not interchangeable concepts. Almost all
5404 <tt>conffiles</tt> are configuration files, but many
5405 configuration files are not <tt>conffiles</tt>.</p>
5408 Note that a script that embeds configuration information
5409 (such as most of the files in <tt>/etc/init.d</tt> and
5410 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5411 configuration file and should be treated as such.</p>
5415 <heading>Location</heading>
5417 Any configuration files created or used by your package
5418 must reside in <tt>/etc</tt>. If there are several you
5419 should consider creating a subdirectory of <tt>/etc</tt>
5420 named after your package.</p>
5423 If your package creates or uses configuration files
5424 outside of <tt>/etc</tt>, and it is not feasible to modify
5425 the package to use the <tt>/etc</tt>, you should still put
5426 the files in <tt>/etc</tt> and create symbolic links to
5427 those files from the location that the package
5432 <heading>Behavior</heading>
5434 Configuration file handling must conform to the following
5438 <p>local changes must be preserved during a package
5442 <p>configuration files must be preserved when the
5443 package is removed, and only deleted when the
5444 package is purged.</p>
5449 The easy way to achieve this behavior is to make the
5450 configuration file a <tt>conffile</tt>. This is
5451 appropriate only if it is possible to distribute a default
5452 version that will work for most installations, although
5453 some system administrators may choose to modify it. This
5454 implies that the default version will be part of the
5455 package distribution, and must not be modified by the
5456 maintainer scripts during installation (or at any other
5461 In order to ensure that local changes are preserved
5462 correctly, no package may contain or make hard links to
5466 Rationale: There are two problems with hard links.
5467 The first is that some editors break the link while
5468 editing one of the files, so that the two files may
5469 unwittingly become different. The second is that
5470 <prgn>dpkg</prgn> might break the hard link while
5471 upgrading <tt>conffile</tt>s.
5477 The other way to do it is via the maintainer scripts.
5478 In this case, the configuration file must not be listed as
5479 a <tt>conffile</tt> and must not be part of the package
5480 distribution. If the existence of a file is required for
5481 the package to be sensibly configured it is the
5482 responsibility of the package maintainer to write scripts
5483 which correctly create, update, maintain and
5484 remove-on-purge the file. These scripts must be idempotent
5485 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5486 re-run them due to errors during installation or removal),
5487 must cope with all the variety of ways <prgn>dpkg</prgn>
5488 can call maintainer scripts, must not overwrite or
5489 otherwise mangle the user's configuration without asking,
5490 must not ask unnecessary questions (particularly during
5491 upgrades), and otherwise be good citizens.</p>
5494 The scripts are not required to configure every possible option for
5495 the package, but only those necessary to get the package
5496 running on a given system. Ideally the sysadmin should not
5497 have to do any configuration other than that done
5498 (semi-)automatically by the <tt>postinst</tt> script.</p>
5501 A common practice is to create a script called
5502 <tt><var>package</var>-configure</tt> and have the
5503 package's <tt>postinst</tt> call it if and only if the
5504 configuration file does not already exist. In certain
5505 cases it is useful for there to be an example or template
5506 file which the maintainer scripts use. Such files should
5507 be in <tt>/usr/share/<package></tt> or
5508 <tt>/usr/lib/<package></tt> with a symbolic link
5509 from <tt>/usr/share/doc/<package>/examples</tt>
5510 if they are examples, and should be
5511 perfectly ordinary <prgn>dpkg</prgn>-handled files
5512 (<em>not</em> <tt>conffiles</tt>).
5516 These two styles of configuration file handling must
5517 not be mixed, for that way lies madness:
5518 <prgn>dpkg</prgn> will ask about overwriting the file
5519 every time the package is upgraded.</p>
5524 <heading>Sharing configuration files</heading>
5526 Packages which specify the same file as
5527 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5532 The maintainer scripts must not alter the conffile of
5533 <em>any</em> package, including the one the scripts belong
5537 If two or more packages use the same configuration file
5538 and it is reasonable for both to be installed at the same
5539 time, one of these packages must be defined as
5540 <em>owner</em> of the configuration file, i.e., it will be
5541 the package to list that distributes the file and lists it
5542 as a <tt>conffile</tt>. Other packages that use the
5543 configuration file must depend on the owning package if
5544 they require the configuration file to operate. If the
5545 other package will use the configuration file if present,
5546 but is capable of operating without it, no dependency need
5550 If it is desirable for two or more related packages to
5551 share a configuration file <em>and</em> for all of the
5552 related packages to be able to modify that configuration
5553 file, then the following should be done:
5557 have one of the related packages (the "core"
5558 package) manage the configuration file with
5559 maintainer scripts as described in the previous
5563 the core package should also provide a program that
5564 the other packages may use to modify the
5565 configuration file.</p>
5569 the related packages must use the provided program
5570 to make any modifications to the configuration file.
5571 They should either depend on the core package to
5572 guarantee that the configuration modifier program is
5573 available or accept gracefully that they cannot
5574 modify the configuration file if it is not.</p>
5579 Sometimes it's appropriate to create a new package which
5580 provides the basic infrastructure for the other packages
5581 and which manages the shared configuration files. (Check
5582 out the <tt>sgml-base</tt> package as an example.)</p>
5586 <heading>User configuration files ("dotfiles")</heading>
5589 Files in <tt>/etc/skel</tt> will automatically be copied
5590 into new user accounts by <prgn>adduser</prgn>. They
5591 should not be referenced there by any program.</p>
5594 Therefore, if a program needs a dotfile to exist in
5595 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5596 should be installed in <tt>/etc/skel</tt> (and listed in
5597 conffiles, if it is not generated and modified dynamically
5598 by the package's installation scripts).</p>
5601 However, programs that require dotfiles in order to
5602 operate sensibly (dotfiles that they do not create
5603 themselves automatically, that is) are a bad thing, and
5604 programs should be configured by the Debian default
5605 installation as close to normal as possible.</p>
5608 Therefore, if a program in a Debian package needs to be
5609 configured in some way in order to operate sensibly that
5610 configuration should be done in a site-wide global
5611 configuration file elsewhere in <tt>/etc</tt>. Only if the
5612 program doesn't support a site-wide default configuration
5613 and the package maintainer doesn't have time to add it
5614 may a default per-user file be placed in
5615 <tt>/etc/skel</tt>.</p>
5618 <tt>/etc/skel</tt> should be as empty as we can make it.
5619 This is particularly true because there is no easy
5620 mechanism for ensuring that the appropriate dotfiles are
5621 copied into the accounts of existing users when a package
5627 <heading>Log files</heading>
5629 The traditional approach to log files has been to set up ad
5630 hoc log rotation schemes using simple shell scripts and
5631 cron. While this approach is highly customizable, it
5632 requires quite a lot of sysadmin work. Even though the
5633 original Debian system helped a little by automatically
5634 installing a system which can be used as a template, this
5635 was deemed not enough.
5639 A better scheme is to use logrotate, a GPL'd program
5640 developed by Red Hat, which centralizes log management. It
5641 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5642 and a directory where packages can drop logrotation info
5643 (<tt>/etc/logrotate.d</tt>).
5647 Log files should usually be named
5648 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5649 log files, or need a separate directory for permissions
5650 reasons (<tt>/var/log</tt> is writable only by
5651 <tt>root</tt>), you should usually create a directory named
5652 <tt>/var/log/<var>package</var></tt>.</p>
5655 Log files must be rotated occasionally so
5656 that they don't grow indefinitely; the best way to do this
5657 is to drop a script into the directory
5658 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5659 logrotate. Here is a good example for a logrotate config
5660 file (for more information see <manref name="logrotate"
5668 /etc/init.d/foo force-reload
5672 Which rotates all files under `/var/log/foo', saves 12
5673 compressed generations, and sends a HUP signal at the end of
5679 Log files should be removed when the package is
5680 purged (but not when it is only removed), by checking the
5681 argument to the <tt>postrm</tt> script (see the <em>Debian
5682 Packaging Manual</em> for details).</p>
5687 <heading>Permissions and owners</heading>
5690 The rules in this section are guidelines for general use.
5691 If necessary you may deviate from the details below.
5692 However, if you do so you must make sure that what is done
5693 is secure and you should try to be as consistent as possible
5694 with the rest of the system. You should probably also
5695 discuss it on <prgn>debian-devel</prgn> first.</p>
5698 Files should be owned by <tt>root.root</tt>, and made
5699 writable only by the owner and universally readable (and
5700 executable, if appropriate).</p>
5703 Directories should be mode 755 or (for group-writability)
5704 mode 2775. The ownership of the directory should be
5705 consistent with its mode--if a directory is mode 2775, it
5706 should be owned by the group that needs write access to
5710 Setuid and setgid executables should be mode 4755 or 2755
5711 respectively, and owned by the appropriate user or group.
5712 They should not be made unreadable (modes like 4711 or
5713 2711 or even 4111); doing so achieves no extra security,
5714 because anyone can find the binary in the freely available
5715 Debian package--it is merely inconvenient. For the same
5716 reason you should not restrict read or execute permissions
5717 on non-set-id executables.</p>
5720 Some setuid programs need to be restricted to particular
5721 sets of users, using file permissions. In this case they
5722 should be owned by the uid to which they are set-id, and
5723 by the group which should be allowed to execute them.
5724 They should have mode 4754; there is no point in making
5725 them unreadable to those users who must not be allowed to
5729 You must not arrange that the system administrator can only
5730 reconfigure the package to correspond to their local
5731 security policy by changing the permissions on a binary.
5732 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5733 to conffiles and other similar objects) have their
5734 permissions reset to the distributed permissions when the
5735 package is reinstalled. Instead you should consider (for
5736 example) creating a group for people allowed to use the
5737 program(s) and making any setuid executables executable
5738 only by that group.</p>
5741 If you need to create a new user or group for your package
5742 there are two possibilities. Firstly, you may need to
5743 make some files in the binary package be owned by this
5744 user or group, or you may need to compile the user or
5745 group id (rather than just the name) into the binary
5746 (though this latter should be avoided if possible, as in
5747 this case you need a statically allocated id).</p>
5750 If you need a statically allocated id, you must ask for a
5751 user or group id from the base system
5752 maintainer, and must not release the package until you
5753 have been allocated one. Once you have been allocated one
5754 you must make the package depend on a version of the base
5755 system with the id present in <tt>/etc/passwd</tt> or
5756 <tt>/etc/group</tt>, or alternatively arrange for your
5757 package to create the user or group itself with the
5758 correct id (using <tt>adduser</tt>) in its pre- or
5759 post-installation script (the latter is to be preferred if
5760 it is possible).</p>
5763 On the other hand, the program might be able to determine the
5764 uid or gid from the group name at runtime, so that a
5765 dynamic id can be used. In this case you should choose an
5766 appropriate user or group name, discussing this on
5767 <prgn>debian-devel</prgn> and checking with the base
5768 system maintainer that it is unique and that they do not
5769 wish you to use a statically allocated id instead. When
5770 this has been checked you must arrange for your package to
5771 create the user or group if necessary using
5772 <prgn>adduser</prgn> in the pre- or post-installation
5773 script (again, the latter is to be preferred if it is
5777 Note that changing the numeric value of an id associated with a name
5778 is very difficult, and involves searching the file system for all
5779 appropriate files. You need to think carefully whether a static or
5780 dynamic id is required, since changing your mind later will cause
5786 <heading>Customized programs</heading>
5788 <sect id="arch-spec">
5789 <heading>Architecture specification strings</heading>
5792 If a program needs to specify an <em>architecture specification
5793 string</em> in some place, the following format should be used:
5795 <arch>-<os>
5797 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5798 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5799 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5800 operating system.</p>
5802 Note, that we don't want to use `<arch>-debian-linux'
5803 to apply to the rule `architecture-vendor-os' since this
5804 would make our programs incompatible to other Linux
5805 distributions. Also note, that we don't use
5806 `<arch>-unknown-linux', since the `unknown' does not
5807 look very good.</p></sect>
5811 <heading>Daemons</heading>
5814 The configuration files <tt>/etc/services</tt>,
5815 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5816 by the <prgn>netbase</prgn> package and may not be modified
5817 by other packages.</p>
5820 If a package requires a new entry in one of these files, the
5821 maintainer should get in contact with the
5822 <prgn>netbase</prgn> maintainer, who will add the entries
5823 and release a new version of the <prgn>netbase</prgn>
5827 The configuration file <tt>/etc/inetd.conf</tt> must not be
5828 modified by the package's scripts except via the
5829 <prgn>update-inetd</prgn> script or the
5830 <prgn>DebianNet.pm</prgn> Perl module.</p>
5833 If a package wants to install an example entry into
5834 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5835 exactly one hash character (<tt>#</tt>). Such lines are
5836 treated as `commented out by user' by the
5837 <prgn>update-inetd</prgn> script and are not changed or
5838 activated during a package updates.</p></sect>
5842 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5845 Some programs need to create pseudo-ttys. This should be done
5846 using Unix98 ptys if the C library supports it. The resulting
5847 program must not be installed setuid root, unless that
5848 is required for other functionality.
5852 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5853 <tt>/var/log/lastlog</tt> must be installed writeable by
5854 group utmp. Programs who need to modify those files must
5855 be installed setgid utmp.
5860 <heading>Editors and pagers</heading>
5863 Some programs have the ability to launch an editor or pager
5864 program to edit or display a text document. Since there are
5865 lots of different editors and pagers available in the Debian
5866 distribution, the system administrator and each user should
5867 have the possibility to choose his/her preferred editor and
5871 In addition, every program should choose a good default
5872 editor/pager if none is selected by the user or system
5876 Thus, every program that launches an editor or pager must
5877 use the EDITOR or PAGER environment variables to determine
5878 the editor/pager the user wants to get started. If these
5879 variables are not set, the programs <tt>/usr/bin/editor</tt>
5880 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5883 These two files are managed through `alternatives.' That is,
5884 every package providing an editor or pager must call the
5885 <prgn>update-alternatives</prgn> script to register these
5889 If it is very hard to adapt a program to make us of the
5890 EDITOR and PAGER variables, that program may be configured
5891 to use <tt>/usr/bin/sensible-editor</tt> and
5892 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5893 respectively. These are two scripts provided in the Debian
5894 base system that check the EDITOR and PAGER variables and
5895 launch the appropriate program or fall back to
5896 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5900 A program may also use the VISUAL environment variable to
5901 determine the user's choice of editor. If it exists, it
5902 should take precedence over EDITOR. This is in fact what
5903 <tt>/usr/bin/sensible-editor</tt> does.</p>
5906 It is not required for a package to depend on
5907 `editor' and `pager', nor is it required for a package to
5908 provide such virtual packages.
5911 The Debian base system already provides an editor and
5920 <sect id="web-appl">
5921 <heading>Web servers and applications</heading>
5924 This section describes the locations and URLs that should
5925 be used by all web servers and web application in the Debian
5931 <p>Cgi-bin executable files are installed in the
5934 /usr/lib/cgi-bin/<cgi-bin-name>
5936 and should be referred to as
5938 http://localhost/cgi-bin/<cgi-bin-name>
5939 </example></p></item>
5942 <item><p>Access to html documents</p>
5945 Html documents for a package are stored in
5946 <tt>/usr/share/doc/<var>package</var></tt> but should
5947 be accessed via symlinks as
5948 <tt>/usr/doc/<var>package</var></tt><footnote> for
5949 backward compatibility, see <ref id="usrdoc"></footnote>
5950 and can be referred to as
5952 http://localhost/doc/<package>/<filename>
5953 </example></p></item>
5956 <item><p>Web Document Root</p>
5959 Web Applications should try to avoid storing files in
5960 the Web Document Root. Instead they should use the
5961 /usr/share/doc/<package> directory for documents and
5962 register the Web Application via the menu package. If
5963 access to the web-root is unavoidable then use
5967 as the Document Root. This might be just a
5968 symbolic link to the location where the sysadmin has
5969 put the real document root.</p>
5972 </enumlist></p></sect>
5976 <heading>Mail transport, delivery and user agents</heading>
5979 Debian packages which process electronic mail, whether
5980 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
5981 must make sure that they are compatible with the
5982 configuration decisions below. Failure to do this may
5983 result in lost mail, broken <tt>From:</tt> lines, and other
5984 serious brain damage!</p>
5987 The mail spool is <tt>/var/spool/mail</tt> and the interface
5988 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
5989 per the FHS). The mail spool is part of the base system
5990 and not part of the MTA package.</p>
5993 All Debian MUAs, MTAs, MDAs and other mailbox accessing
5994 programs (like IMAP daemons) must lock the mailbox in an
5995 NFS-safe way. This means that <tt>fcntl()</tt> locking must
5996 be combined with dot locking. To avoid deadlocks, a
5997 program should use <tt>fcntl()</tt> first and dot locking
5998 after this or alternatively implement the two locking
5999 methods in a non blocking way<footnote>
6001 If it is not possible to establish both locks, the
6002 system shouldn't wait for the second lock to be
6003 established, but remove the first lock, wait a (random)
6004 time, and start over locking again.</p>
6005 </footnote>. Using the functions <tt>maillock</tt> and
6006 <tt>mailunlock</tt> provided by the
6007 <tt>liblockfile*</tt><footnote>
6009 <tt>liblockfile</tt> version >>1.01</p>
6010 </footnote> packages is the recommended way to realize this.
6014 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6015 unless the user has chosen otherwise. A MUA may remove a
6016 mailbox (unless it has nonstandard permissions) in which
6017 case the MTA or another MUA must recreate it if needed.
6018 Mailboxes must be writable by group mail.</p>
6021 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6022 be setgid mail to do the locking mentioned above (and
6023 must obviously avoid accessing other users' mailboxes
6024 using this privilege).</p>
6027 <tt>/etc/aliases</tt> is the source file for the system mail
6028 aliases (e.g., postmaster, usenet, etc.)--it is the one
6029 which the sysadmin and <tt>postinst</tt> scripts may edit.
6030 After <tt>/etc/aliases</tt> is edited the program or human
6031 editing it must call <prgn>newaliases</prgn>. All MTA
6032 packages must come with a <prgn>newaliases</prgn> program,
6033 even if it does nothing, but older MTA packages do not do
6034 this so programs should not fail if <prgn>newaliases</prgn>
6035 cannot be found.</p>
6038 The convention of writing <tt>forward to
6039 <var>address</var></tt> in the mailbox itself is not
6040 supported. Use a <tt>.forward</tt> file instead.</p>
6043 The <prgn>rmail</prgn> program used by UUCP
6044 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6045 Likewise, <prgn>rsmtp</prgn>, for receiving
6046 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6050 If you need to know what name to use (for example) on
6051 outgoing news and mail messages which are generated locally,
6052 you should use the file <tt>/etc/mailname</tt>. It will
6053 contain the portion after the username and <tt>@</tt> (at)
6054 sign for email addresses of users on the machine (followed
6058 A package should check for the existence of this file. If
6059 it exists it should use it without comment. (An MTA's
6060 prompting configuration script may wish to prompt the user
6061 even if it finds this file exists.) If it does not exist it
6062 should prompt the user for the value and store it in
6063 <tt>/etc/mailname</tt> as well as using it in the package's
6064 configuration. The prompt should make it clear that the
6065 name will not just be used by that package. For example, in
6066 this situation the INN package says:
6068 Please enter the `mail name' of your system. This is the
6069 hostname portion of the address to be shown on outgoing
6070 news and mail messages. The default is
6071 <var>syshostname</var>, your system's host name. Mail
6072 name [`<var>syshostname</var>']:
6074 where <var>syshostname</var> is the output of <tt>hostname
6075 --fqdn</tt>.</p></sect>
6079 <heading>News system configuration</heading>
6082 All the configuration files related to the NNTP (news)
6083 servers and clients should be located under
6084 <tt>/etc/news</tt>.</p>
6087 There are some configuration issues that apply to a number
6088 of news clients and server packages on the machine. These
6092 <tag>/etc/news/organization</tag>
6093 <item><p>A string which should appear as the
6094 organization header for all messages posted
6095 by NNTP clients on the machine</p></item>
6097 <tag>/etc/news/server</tag>
6098 <item><p>Contains the FQDN of the upstream NNTP
6099 server, or localhost if the local machine is
6100 an NNTP server.</p></item>
6103 Other global files may be added as required for cross-package news
6104 configuration.</p></sect>
6108 <heading>Programs for the X Window System</heading>
6111 <em>Programs that may be configured with support for the X Window
6112 System</em> must be configured to do so and must declare any
6113 package dependencies necessary to satisfy their runtime
6114 requirements when using the X Window System, unless the package
6115 in question is of standard or higher priority, in which case
6116 X-specific binaries may be split into a separate package, or
6117 alternative versions of the package with X support may be
6123 <em>Packages which provide an X server</em> that, directly or
6124 indirectly, communicates with real input and display hardware
6125 should declare in their control data that they provide the
6126 virtual package <tt>xserver</tt>.
6129 This implements current practice, and provides an actual
6130 policy for usage of the "xserver" virtual package which
6131 appears in the virtual packages list. In a nutshell, X
6132 servers that interface directly with the display and input
6133 hardware or via another subsystem (e.g., GGI) should provide
6134 xserver. Things like Xvfb, Xnest, and Xprt should not.
6140 <em>Packages that provide a terminal emulator</em> for the X
6141 Window System which support a terminal type with a terminfo
6142 description provided in the <tt>ncurses-base</tt> package
6143 should declare in their control data that they provide the
6144 virtual package <tt>x-terminal-emulator</tt>. They should
6145 also register themselves as an alternative for
6146 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6151 <em>Packages that provide window managers</em> should declare in
6152 their control data that they provide the virtual package
6153 <tt>x-window-manager</tt>. They should also register themselves as an
6154 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6155 calculated as follows:
6157 <item>Start with a priority of 20.</item>
6158 <item>If the window manager supports the Debian menu system,
6159 add 20 points if this support is available in the
6160 package's default configuration (i.e., no
6161 configuration files belonging to the system or user
6162 have to be edited to activate the feature); if
6163 configuration files must be modified, add only 10
6165 <item>If the window manager permits the X session to be
6166 restarted using a <em>different</em> window manager
6167 (without killing the X server) in its default
6168 configuration, add 10 points; otherwise add
6174 <em>Packages that provide fonts for the X Window System</em>
6175 must do a number of things to ensure that they are both
6176 available without modification of the X or font server
6177 configuration, and that they do not corrupt files used by
6178 other font packages to register information about themselves.
6181 Fonts of any type supported by the X Window System
6182 should be be in a separate binary package from any
6183 executables, libraries, or documentation (except that
6184 specific to the fonts shipped); if a program or
6185 library is <em>unusable</em> without one or more
6186 specific fonts, the package containing the program or
6187 library should declare a dependency on the package(s)
6188 containing the font(s) it requires.
6191 BDF fonts should be converted to PCF fonts with the
6192 <tt>bdftopcf</tt> utility (available in the
6193 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6194 placed in a directory that corresponds to their
6198 100 dpi fonts should be placed in
6199 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6202 75 dpi fonts should be placed in
6203 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6206 Character-cell fonts, cursor fonts, and other
6207 low-resolution fonts should be placed in
6208 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6213 Speedo fonts should be placed in
6214 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6217 Type 1 fonts should be placed in
6218 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6219 metric files are available, they may be placed here as
6223 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6224 other than those listed above should be neither created nor
6225 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6226 excepted for historical reasons, but installation of files into
6227 these directories remains discouraged.)
6230 Font packages may, instead of placing files directly in
6231 the X font directories listed above, provide symbolic links in
6232 the font directory which point to the files' actual location
6233 in the filesystem. Such a location should comply with the
6237 Font packages should not contain both 75dpi and 100dpi
6238 versions of a font. If both are available, they should be
6239 provided in separate binary packages with "-75dpi" or "-100dpi"
6240 appended to the names of the packages containing the
6241 corresponding fonts.
6244 Fonts destined for the <tt>misc</tt> subdirectory should
6245 not be included in the same package as 75dpi or 100dpi fonts;
6246 instead, they should be provided in a separate package with
6247 "-misc" appended to its name.
6250 Font packages <em>must not</em> provide the files
6251 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6252 <tt>fonts.scale</tt> in a font directory.
6255 <tt>fonts.dir</tt> files must not be provided at
6259 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6260 files, if needed, should be provided in the
6262 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6263 where <em>fontdir</em> is the name of the
6265 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6266 package's corresponding fonts are stored (e.g.,
6267 <tt>75dpi</tt> or <tt>misc</tt>),
6268 <em>package</em> is the name of the package that
6269 provides these fonts, and <em>extension</em> is
6270 either <tt>scale</tt> or <tt>alias</tt>,
6271 whichever corresponds to the file
6277 Font packages must declare a dependency on
6278 <tt>xutils</tt> and, in the package
6279 post-installation and post-removal scripts, invoke the
6280 <tt>mkfontdir</tt> command on each directory into
6281 which they installed fonts.
6284 Font packages that provide one or more
6285 <tt>fonts.scale</tt> files as described above must declare a
6286 versioned dependency on <tt>xutils (>=
6287 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6288 directory into which they installed fonts
6289 <em>before</em> invoking <tt>mkfontdir</tt> on that
6290 directory. This invocation must occur in both the
6291 post-installation and post-removal scripts.
6294 Font packages that provide one or more
6295 <tt>fonts.alias</tt> files as described above must
6296 declare a versioned dependency on <tt>xutils
6297 (>= 4.0.2)</tt> and, in the package
6298 post-installation and post-removal scripts, invoke
6299 <tt>update-fonts-alias</tt> on each directory into
6300 which they installed fonts.
6303 Font packages must not provide alias names for the
6304 fonts they include which collide with alias names already in
6305 use by fonts already packaged.
6308 Font packages must not provide fonts with the same XLFD
6309 registry name as another font already packaged.
6315 <em>Application defaults</em> files must be installed in the
6316 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6317 localized subdirectory of <tt>/etc/X11/</tt> as described in
6318 the <em>X Toolkit Intrinsics - C Language Interface</em>
6319 manual is also permitted). They must be registered as
6320 <em>conffile</em>s or handled as configuration files. For
6321 programs that are not linked against the X Toolkit (Xt)
6322 library, customization of programs' X resources may also be
6323 supported with the provision of a file with the same name as
6324 that of the package placed in the
6325 <tt>/etc/X11/Xresources/</tt> directory, which must
6326 registered as a <em>conffile</em> or handled as a
6327 configuration file. <em>Important:</em> packages that
6328 install files into the <tt>/etc/X11/Xresources/</tt>
6329 directory <em>must</em> declare a conflict with <tt>xbase
6330 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6331 possible for the installing package to destroy a
6332 previously-existing <tt>/etc/X11/Xresources</tt> file which
6333 had been customized by the system administrator.
6337 <em>Packages using the X Window System should abide by the FHS
6338 standard whenever possible</em>; they should install binaries,
6339 libraries, manual pages, and other files in FHS-mandated
6340 locations wherever possible. This means that files must
6341 not be installed into <tt>/usr/X11R6/bin/</tt>,
6342 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6343 this is necessary for the package to operate properly.
6344 Configuration files for window managers and display managers
6345 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6346 corresponding to the package name due to these programs'
6347 tight integration with the mechanisms of the X Window
6348 System. Application-level programs should use the
6349 <tt>/etc/</tt> directory unless otherwise mandated by
6350 policy. The installation of files into subdirectories of
6351 <tt>/usr/X11R6/include/X11/</tt> and
6352 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6353 package maintainers should determine if subdirectories of
6354 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6355 instead (symlinks from the X11R6 directories to
6356 FHS-compliant locations is encouraged if the program is not
6357 easily configured to look elsewhere for its files).
6358 Packages must not provide -- or install files into -- the
6359 directories <tt>/usr/bin/X11/</tt>,
6360 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6361 Files within a package should, however, make reference to
6362 these directories, rather than their X11R6-named
6363 counterparts <tt>/usr/X11R6/bin/</tt>,
6364 <tt>/usr/X11R6/include/X11/</tt>, and
6365 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6366 referred to have not been moved to FHS-compliant locations.
6370 <em>Programs that require the non-DFSG-compliant OSF/Motif
6371 library</em> should be compiled against and tested with
6372 LessTif (a free re-implementation of Motif) instead. If the
6373 maintainer judges that the program or programs do not work
6374 sufficiently well with LessTif to be distributed and
6375 supported, but do so when compiled against Motif, then two
6376 versions of the package should be created; one linked
6377 statically against Motif and with <tt>-smotif</tt> appended
6378 to the package name, and one linked dynamically against
6379 Motif and with <tt>-dmotif</tt> appended to the package
6380 name. Both Motif-linked versions are dependent upon
6381 non-DFSG-compliant software and thus cannot be uploaded to
6382 the main distribution; if the software is itself
6383 DFSG-compliant it may be uploaded to the contrib
6384 distribution. While known existing versions of OSF/Motif
6385 permit unlimited redistribution of binaries linked against
6386 the library (whether statically or dynamically), it is the
6387 package maintainer's responsibility to determine whether
6388 this is permitted by the license of the copy of OSF/Motif in
6389 his or her possession.
6395 <heading>Emacs lisp programs</heading>
6398 Please refer to the `Debian Emacs Policy' (documented in
6399 <tt>debian-emacs-policy.gz</tt> of the
6400 <prgn>emacsen-common</prgn> package) for details of how to
6401 package emacs lisp programs.</p></sect>
6405 <heading>Games</heading>
6408 The permissions on /var/games are 755
6409 <tt>root.root</tt>.</p>
6412 Each game decides on its own security policy.</p>
6415 Games which require protected, privileged access to
6416 high-score files, savegames, etc., may be made
6417 set-<em>group</em>-id (mode 2755) and owned by
6418 <tt>root.games</tt>, and use files and directories with
6419 appropriate permissions (770 <tt>root.games</tt>, for
6420 example). They must not be made
6421 set-<em>user</em>-id, as this causes security problems. (If
6422 an attacker can subvert any set-user-id game they can
6423 overwrite the executable of any other, causing other players
6424 of these games to run a Trojan horse program. With a
6425 set-group-id game the attacker only gets access to less
6426 important game data, and if they can get at the other
6427 players' accounts at all it will take considerably more
6431 Some packages, for example some fortune cookie programs, are
6432 configured by the upstream authors to install with their
6433 data files or other static information made unreadable so
6434 that they can only be accessed through set-id programs
6435 provided. You should not do this in a Debian package: anyone can
6436 download the <tt>.deb</tt> file and read the data from it,
6437 so there is no point making the files unreadable. Not
6438 making the files unreadable also means that you don't have
6439 to make so many programs set-id, which reduces the risk of a
6443 As described in the FHS, binaries of games should be
6444 installed in the directory <tt>/usr/games</tt>. This also
6445 applies to games that use the X Window System. Manual pages
6446 for games (X and non-X games) should be installed in
6447 <tt>/usr/share/man/man6</tt>.</p>
6451 <chapt><heading>Documentation</heading>
6455 <heading>Manual pages</heading>
6458 You should install manual pages in <prgn>nroff</prgn> source
6459 form, in appropriate places under <tt>/usr/share/man</tt>. You
6460 should only use sections 1 to 9 (see the FHS for more
6461 details). You must not install a preformatted `cat
6465 Each program, utility, and function should have an
6466 associated manpage included in the same package. It is
6467 suggested that all configuration files also have a manual
6468 page included as well.
6472 If no manual page is available for a particular program,
6473 utility, function or configuration file and this is reported as a bug on
6474 debian-bugs, a symbolic link from the requested manual page
6475 to the <manref name="undocumented" section="7"> manual page
6476 may be provided. This symbolic link can be created from
6477 <tt>debian/rules</tt> like this:
6479 ln -s ../man7/undocumented.7.gz \
6480 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6482 This manpage claims that the lack of a manpage has been
6483 reported as a bug, so you may only do this if it really has
6484 (you can report it yourself, if you like). Do not close the
6485 bug report until a proper manpage is available.</p>
6488 You may forward a complaint about a missing manpage to the
6489 upstream authors, and mark the bug as forwarded in the
6490 Debian bug tracking system. Even though the GNU Project do
6491 not in general consider the lack of a manpage to be a bug,
6492 we do--if they tell you that they don't consider it a bug
6493 you should leave the bug in our bug tracking system open
6497 Manual pages should be installed compressed using <tt>gzip
6501 If one manpage needs to be accessible via several names it
6502 is better to use a symbolic link than the <tt>.so</tt>
6503 feature, but there is no need to fiddle with the relevant
6504 parts of the upstream source to change from <tt>.so</tt> to
6505 symlinks--don't do it unless it's easy. You should not create hard
6506 links in the manual page directories, nor put
6507 absolute filenames in <tt>.so</tt> directives. The filename
6508 in a <tt>.so</tt> in a manpage should be relative to the
6509 base of the manpage tree (usually
6510 <tt>/usr/share/man</tt>).</p></sect>
6514 <heading>Info documents</heading>
6517 Info documents should be installed in <tt>/usr/share/info</tt>.
6518 They should be compressed with <tt>gzip -9</tt>.</p>
6521 Your package should call <prgn>install-info</prgn> to update the Info
6523 file, in its post-installation script:
6525 install-info --quiet --section Development Development \
6526 /usr/share/info/foobar.info
6530 It is a good idea to specify a section for the location of
6531 your program; this is done with the <tt>--section</tt>
6532 switch. To determine which section to use, you should look
6533 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6534 relevant (or create a new section if none of the current
6535 sections are relevant). Note that the <tt>--section</tt>
6536 flag takes two arguments; the first is a regular expression
6537 to match (case-insensitively) against an existing section,
6538 the second is used when creating a new one.</p>
6541 You should remove the entries in the pre-removal script:
6543 install-info --quiet --remove /usr/share/info/foobar.info
6547 If <prgn>install-info</prgn> cannot find a description entry
6548 in the Info file you must supply one. See <manref
6549 name="install-info" section="8"> for details.</p>
6553 <heading>Additional documentation</heading>
6556 Any additional documentation that comes with the package may
6557 be installed at the discretion of the package maintainer.
6558 Text documentation should be installed in a directory
6559 <tt>/usr/share/doc/<var>package</var></tt>, where
6560 <var>package</var> is the name of the package, and
6561 compressed with <tt>gzip -9</tt> unless it is small.</p>
6564 If a package comes with large amounts of documentation which
6565 many users of the package will not require you should create
6566 a separate binary package to contain it, so that it does not
6567 take up disk space on the machines of users who do not need
6568 or want it installed.</p>
6571 It is often a good idea to put text information files
6572 (<tt>README</tt>s, changelogs, and so forth) that come with
6573 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6574 in the binary package. However, you don't need to install
6575 the instructions for building and installing the package, of
6579 Files in <tt>/usr/share/doc</tt> should not be referenced by
6580 any program, and the system administrator should be able to
6581 delete them without causing any programs to break. Any files
6582 that are referenced by programs but are also useful as
6583 standalone documentation should be installed under
6584 <tt>/usr/share/<package>/</tt> and symlinked in
6585 <tt>/usr/share/doc/<package>/</tt>.
6591 <heading>Accessing the documentation</heading>
6594 Former Debian releases placed all additional documentation
6595 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6597 <tt>/usr/share/doc/<var>package</var></tt>, each package
6598 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6599 that points to the new location of its documentation in
6600 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6601 symlinks will be removed in the future, but they have to be
6602 there for compatibility reasons until all packages have
6603 moved and the policy is changed accordingly.</footnote>.
6604 The symlink must be created when the package is installed;
6605 it cannot be contained in the package itself due to problems
6606 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6607 this is to put the following in the package's
6608 <prgn>postinst</prgn>:
6610 if [ "$1" = "configure" ]; then
6611 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6612 -a -d /usr/share/doc/#PACKAGE# ]; then
6613 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6617 And the following in the package's <prgn>prerm</prgn>:
6619 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6620 -a -L /usr/doc/#PACKAGE# ]; then
6621 rm -f /usr/doc/#PACKAGE#
6628 <heading>Preferred documentation formats</heading>
6631 The unification of Debian documentation is being carried out
6635 If your package comes with extensive documentation in a
6636 mark up format that can be converted to various other formats
6637 you should if possible ship HTML versions in a binary
6638 package, in the directory
6639 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6642 <p>The rationale: The important thing here is that HTML
6643 docs should be available in <em>some</em> package, not
6644 necessarily in the main binary package, though. </p>
6649 Other formats such as PostScript may be provided at your
6653 <sect id="copyrightfile">
6654 <heading>Copyright information</heading>
6657 Every package must be accompanied by a verbatim copy of its
6658 copyright and distribution license in the file
6659 /usr/share/doc/<package-name>/copyright. This file must
6660 neither be compressed nor be a symbolic link.</p>
6663 In addition, the copyright file must say where the upstream
6664 sources (if any) were obtained, and should explain briefly what
6665 modifications were made in the Debian version of the package
6666 compared to the upstream one. It should name the original
6667 authors of the package and the Debian maintainer(s) who were
6668 involved with its creation.</p>
6671 A copy of the file which will be installed in
6672 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6673 in <tt>debian/copyright</tt>.</p>
6677 /usr/share/doc/<package-name> may be a symbolic link to a
6678 directory in /usr/share/doc only if two packages both come from
6679 the same source and the first package has a "Depends"
6680 relationship on the second. These rules are important
6681 because copyrights must be extractable by mechanical
6685 Packages distributed under the UCB BSD license, the Artistic
6686 license, the GNU GPL, and the GNU LGPL should refer to the
6687 files /usr/share/common-licenses/BSD,
6688 /usr/share/common-licenses/Artistic,
6689 /usr/share/common-licenses/GPL, and
6690 /usr/share/common-licenses/LGPL.
6693 Why "licenses" and not "copyright"? Because
6694 <tt>/usr/doc/copyright</tt> used to contain all the
6695 copyright files, plus the four common licenses GPL,
6696 LGPL, Artistic and BSD. Now individual copyright files
6697 for packages are no longer in a common directory. Once
6698 <tt>/usr/doc/copyright</tt> is almost empty it makes
6699 sense to rename "copyright" to "licenses"
6702 Why "common-licenses" and not "licenses"? Because if I
6703 put just "licenses" I'm sure I will receive a bug report
6704 saying "license foo is not included in the licenses
6705 directory. They are not all the licenses, just a few
6706 common ones. I could use /usr/share/doc/common-licenses
6707 but I think this is too long, and, after all, the GPL
6708 does not "document" anything, it is merely a license.
6714 You should not use the copyright file as a general <tt>README</tt>
6715 file. If your package has such a file it should be
6716 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6717 <tt>README.Debian</tt> or some other appropriate place.</p>
6721 <heading>Examples</heading>
6724 Any examples (configurations, source files, whatever),
6725 should be installed in a directory
6726 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6727 files should not be referenced by any program--they're there
6728 for the benefit of the system administrator and users, as
6729 documentation only. Architecture-specific example files
6730 should be installed in a directory
6731 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6732 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6733 to files in it. Or the latter directory may be a symlink to
6737 <sect id="instchangelog">
6738 <heading>Changelog files</heading>
6741 Packages that are not Debian-native must contain a copy of
6742 <tt>debian/changelog</tt> file from the Debian source tree
6743 in <tt>/usr/share/doc/<var>package</var></tt> as
6744 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6745 available, it should be accessible as
6746 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6747 plain text. If the upstream changelog is distributed in
6748 HTML, it should be made available in that form as
6749 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6750 and the <tt>changelog.gz</tt> should be generated using, eg,
6751 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6752 do not already conform to this naming convention, then this
6753 may be achieved either by renaming the files, or adding a
6754 symbolic link, at the maintainer's discretion.
6757 Rationale: People should not have to look into two
6758 places for upstream changelogs merely because they are
6766 All these files should be installed compressed using <tt>gzip -9</tt>,
6767 as they will become large with time even if they start out
6772 If the package has only one changelog which is used both as
6773 the Debian changelog and the upstream one because there is
6774 no separate upstream maintainer then that changelog should
6775 usually be installed as
6776 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6777 there is a separate upstream maintainer, but no upstream
6778 changelog, then the Debian changelog should still be called
6779 <tt>changelog.Debian.gz</tt>.</p>