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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>
1184 <sect1 id="standardsversion">
1185 <heading>Standards conformance</heading>
1188 In the source package's <tt>Standards-Version</tt> control
1189 field, you must specify the most recent version number of
1190 this policy document with which your package complies.
1191 The current version number is &version;.
1195 This information may be used to file bug reports
1196 automatically if your package becomes too much out of
1201 The version number has four components--major and minor
1202 version number and major and minor patch level. When the
1203 standards change in a way that requires every package to
1204 change the major number will be changed. Significant
1205 changes that will require work in many packages will be
1206 signaled by a change to the minor number. The major patch
1207 level will be changed for any change to the meaning of the
1208 standards, however small; the minor patch level will be
1209 changed when only cosmetic, typographical or other edits
1210 are made which neither change the meaning of the document
1211 nor affect the contents of packages.</p>
1214 Thus only the first three components of the policy version
1215 are significant in the <em>Standards-Version</em> control
1216 field, and so either these three components or the all
1217 four components may be specified.
1220 In the past, people specified the full version number
1221 in the Standards-Version field, for example `2.3.0.0'.
1222 Since minor patch-level changes don't introduce new
1223 policy, it was thought it would be better to relax
1224 policy and only require the first 3 components to be
1225 specified, in this example `2.3.0'. All four
1226 components may still be used if someone wishes to do
1233 You should regularly, and especially if your package has
1234 become out of date, check for the newest Policy Manual
1235 available and update your package, if necessary. When your
1236 package complies with the new standards you should update the
1237 <tt>Standards-Version</tt> source package field and
1241 See the file <tt>upgrading-checklist</tt> for
1242 information about policy which has changed between
1243 different versions of this document.
1251 <heading>Package relationships</heading>
1254 Source packages should specify which binary packages they
1255 require to be installed or not to be installed in order to
1256 build correctly. For example, if building a package
1257 requires a certain compiler, then the compiler should be
1258 specified as a build-time dependency.
1262 It is not necessary to explicitly specify build-time
1263 relationships on a minimal set of packages that are always
1264 needed to compile, link and put in a Debian package a
1265 standard "Hello World!" program written in C or C++. The
1266 required packages are called <em>build-essential</em>, and
1267 an informational list can be found in
1268 <tt>/usr/share/doc/build-essential/list</tt> (which is
1269 contained in the <tt>build-essential</tt>
1275 <p>This allows maintaining the list separately
1276 from the policy documents (the list does not
1277 need the kind of control that the policy
1283 Having a separate package allows one to install
1284 the build-essential packages on a machine, as
1285 well as allowing other packages such as task
1286 packages to require installation of the
1287 build-essential packages using the depends
1293 The separate package allows bug reports against
1294 the list to be categorized separately from
1295 the policy management process in the BTS.
1305 When specifying the set of build-time dependencies, one
1306 should list only those packages explicitly required by the
1307 build. It is not necessary to list packages which are
1308 required merely because some other package in the list of
1309 build-time dependencies depends on them.
1312 The reason for this is that dependencies change, and
1313 you should list all those packages, and <em>only</em>
1314 those packages that <em>you</em> need directly. What
1315 others need is their business. For example, if you
1316 only link against <tt>libimlib</tt>, you will need to
1317 build-depend on <package>libimlib2-dev</package> but
1318 not against any <tt>libjpeg*</tt> packages, even
1319 though <tt>libimlib2-dev</tt> currently depends on
1320 them: installation of <package>libimlib2-dev</package>
1321 will automatically ensure that all of its run-time
1322 dependencies are satisfied.
1328 If build-time dependencies are specified, it must be
1329 possible to build the package and produce working binaries
1330 on a system with only essential and build-essential
1331 packages installed and also those required to satisfy the
1332 build-time relationships (including any implied
1333 relationships). In particular, this means that version
1334 clauses should be used rigorously in build-time
1335 relationships so that one cannot produce bad or
1336 inconsistently configured packages when the relationships
1337 are properly satisfied.
1341 <heading>Changes to the upstream sources</heading>
1344 If changes to the source code are made that are not
1345 specific to the needs of the Debian system, they should be
1346 sent to the upstream authors in whatever form they prefer
1347 so as to be included in the upstream version of the
1351 If you need to configure the package differently for
1352 Debian or for Linux, and the upstream source doesn't
1353 provide a way to do so, you should add such configuration
1354 facilities (for example, a new <prgn>autoconf</prgn> test
1355 or <tt>#define</tt>) and send the patch to the upstream
1356 authors, with the default set to the way they originally
1357 had it. You can then easily override the default in your
1358 <tt>debian/rules</tt> or wherever is appropriate.</p>
1361 You should make sure that the <prgn>configure</prgn> utility
1362 detects the correct architecture specification string
1363 (refer to <ref id="arch-spec"> for details).</p>
1366 If you need to edit a <prgn>Makefile</prgn> where
1367 GNU-style <prgn>configure</prgn> scripts are used, you
1368 should edit the <tt>.in</tt> files rather than editing the
1369 <prgn>Makefile</prgn> directly. This allows the user to
1370 reconfigure the package if necessary. You should
1371 <em>not</em> configure the package and edit the generated
1372 <prgn>Makefile</prgn>! This makes it impossible for
1373 someone else to later reconfigure the package.</p></sect1>
1377 <heading>Documenting your changes</heading>
1380 You should document your changes and updates to the source
1381 package properly in the <tt>debian/changelog</tt> file. (Note
1382 that mistakes in changelogs are usually best rectified by
1383 making a new changelog entry rather than "rewriting history"
1384 by editing old changelog entries.)</p>
1387 In non-experimental packages you must use a format for
1388 <tt>debian/changelog</tt> which is supported by the most
1389 recent released version of <prgn>dpkg</prgn>.
1392 If you wish to use an alternative format, you may do
1393 so as long as you include a parser for it in your
1394 source package. The parser must have an API
1395 compatible with that expected by
1396 <prgn>dpkg-genchanges</prgn> and
1397 <prgn>dpkg-gencontrol</prgn>. If there is general
1398 interest in the new format, you should contact the
1399 <package>dpkg</package> maintainer to have the parser
1400 script for it included in the <prgn>dpkg</prgn>
1401 package. (You will need to agree that the parser and
1402 its manpage may be distributed under the GNU GPL, just
1403 as the rest of `dpkg' is.)
1411 <heading>Error trapping in makefiles</heading>
1414 When <prgn>make</prgn> invokes a command in a makefile
1415 (including your package's upstream makefiles and
1416 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1417 means that <tt>sh</tt>'s usual bad error handling
1418 properties apply: if you include a miniature script as one
1419 of the commands in your makefile you'll find that if you
1420 don't do anything about it then errors are not detected
1421 and <prgn>make</prgn> will blithely continue after
1425 Every time you put more than one shell command (this
1426 includes using a loop) in a makefile command you
1427 must make sure that errors are trapped. For
1428 simple compound commands, such as changing directory and
1429 then running a program, using <tt>&&</tt> rather
1430 than semicolon as a command separator is sufficient. For
1431 more complex commands including most loops and
1432 conditionals you should include a separate <tt>set -e</tt>
1433 command at the start of every makefile command that's
1434 actually one of these miniature shell scripts.</p></sect1>
1438 <heading>Obsolete constructs and libraries</heading>
1441 The include file <prgn><varargs.h></prgn> is
1442 provided to support end-users compiling very old software;
1443 the library <tt>libtermcap</tt> is provided to support the
1444 execution of software which has been linked against it
1445 (either old programs or those such as Netscape which are
1446 only available in binary form).</p>
1449 Debian packages should be patched to use
1450 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1457 <chapt id="controlfields"><heading>Control files and their fields</heading>
1460 Many of the tools in the package management suite manipulate
1461 data represented in a common format, known as <em>control
1462 data</em>. The data is often stored in <em>control
1463 files</em>. Binary and source packages have control files,
1464 and the <tt>.changes</tt> files which control the installation
1465 of uploaded files are also in control file format.
1466 <prgn>Dpkg</prgn>'s internal databases are in a similar
1470 <sect><heading>Syntax of control files</heading>
1473 A control file consists of one or more paragraphs of fields.
1474 The paragraphs are separated by blank lines. Some control
1475 files allow only one paragraph; others allow several, in
1476 which case each paragraph usually refers to a different
1477 package. (For example, in source packages, the first
1478 paragraph refers to the source package, and later paragraphs
1479 refer to binary packages generated from the source.)
1483 Each paragraph consists of a series of data fields; each
1484 field consists of the field name, followed by a colon and
1485 then the data/value associated with that field. It ends at
1486 the end of the line. Horizontal whitespace (spaces and
1487 tabs) may occur immediately before or after the value and is
1488 ignored there; it is conventional to put a single space
1489 after the colon. For example, a field might be:
1493 the field name is <tt>Package</tt> and the field value
1498 Some fields' values may span several lines; in this case
1499 each continuation line <em>must</em> start with a space or
1500 tab. Any trailing spaces or tabs at the end of individual
1501 lines of a field value are ignored.
1505 Except where otherwise stated only a single line of data is
1506 allowed and whitespace is not significant in a field body.
1507 Whitespace must not appear inside names (of packages,
1508 architectures, files or anything else) or version numbers,
1509 or between the characters of multi-character version
1514 Field names are not case-sensitive, but it is usual to
1515 capitalize the field names using mixed case as shown below.
1519 Blank lines, or lines consisting only of spaces and tabs,
1520 are not allowed within field values or between fields - that
1521 would mean a new paragraph.
1526 <sect><heading>List of fields</heading>
1528 This list here is not supposed to be exhaustive. Most fields
1529 are dealt with elsewhere in this document.
1531 <sect1 id="f-Package"><heading><tt>Package</tt>
1535 The name of the binary package. Package names consist of
1536 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1537 (plus, minus and full stop).
1541 They must be at least two characters long and must start
1542 with an alphanumeric character and not be all digits. The
1543 use of lowercase package names is strongly recommended
1544 unless the package you're building (or referring to, in
1545 other fields) is already using uppercase.</p>
1548 <sect1 id="f-Version"><heading><tt>Version</tt>
1552 This lists the source or binary package's version number -
1553 see <ref id="versions">.
1559 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1563 The most recent version of the standards (the policy
1564 manual and associated texts) with which the package
1565 complies. This is updated manually when editing the
1566 source package to conform to newer standards; it can
1567 sometimes be used to tell when a package needs attention.
1568 Its format is described above; see
1569 <ref id="standardsversion">.
1574 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1578 In a <tt>.changes</tt> file or parsed changelog output
1579 this contains the (space-separated) name(s) of the
1580 distribution(s) where this version of the package should
1581 be installed. Valid distributions are determined by the
1582 archive maintainers.
1584 Current distribution names are:
1586 <tag><em>stable</em></tag>
1589 This is the current `released' version of Debian
1590 GNU/Linux. Once the distribution is
1591 <em>stable</em> only security fixes and other
1592 major bug fixes are allowed. When changes are
1593 made to this distribution, the release number is
1594 increased (for example: 2.2r1 becomes 2.2r2 then
1599 <tag><em>unstable</em></tag>
1602 This distribution value refers to the
1603 <em>developmental</em> part of the Debian
1604 distribution tree. New packages, new upstream
1605 versions of packages and bug fixes go into the
1606 <em>unstable</em> directory tree. Download from
1607 this distribution at your own risk.
1611 <tag><em>testing</em></tag>
1614 This distribution value refers to the
1615 <em>testing</em> part of the Debian distribution
1616 tree. It receives its packages from the
1617 unstable distribution after a short time lag to
1618 ensure that there are no major issues with the
1619 unstable packages. It is less prone to breakage
1620 than unstable, but still risky. It is not
1621 possible to upload packages directly to
1626 <tag><em>frozen</em></tag>
1629 From time to time, the <em>frozen</em>
1630 distribution enters a state of `code-freeze' in
1631 anticipation of release as a <em>stable</em>
1632 version. During this period of testing only
1633 fixes for existing or newly-discovered bugs will
1634 be allowed. The exact details of this stage are
1635 determined by the Release Manager.
1639 <tag><em>experimental</em></tag>
1642 The packages with this distribution value are
1643 deemed by their maintainers to be high
1644 risk. Oftentimes they represent early beta or
1645 developmental packages from various sources that
1646 the maintainers want people to try, but are not
1647 ready to be a part of the other parts of the
1648 Debian distribution tree. Download at your own
1654 You should list <em>all</em> distributions that the
1655 package should be installed into.
1664 <chapt id="versions"><heading>Version numbering</heading>
1667 Every package has a version number recorded in its
1668 <tt>Version</tt> control file field.
1672 The package management system imposes an ordering on version
1673 numbers, so that it can tell whether packages are being up- or
1674 downgraded and so that package system front end applications
1675 can tell whether a package it finds available is newer than
1676 the one installed on the system. The version number format
1677 has the most significant parts (as far as comparison is
1678 concerned) at the beginning.
1682 The version number format is:
1683 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1687 The three components here are:
1689 <tag><var>epoch</var></tag>
1693 This is a single (generally small) unsigned integer. It
1694 may be omitted, in which case zero is assumed. If it is
1695 omitted then the <var>upstream_version</var> may not
1700 It is provided to allow mistakes in the version numbers
1701 of older versions of a package, and also a package's
1702 previous version numbering schemes, to be left behind.
1707 <tag><var>upstream_version</var></tag>
1711 This is the main part of the version number. It is
1712 usually the version number of the original (`upstream')
1713 package from which the <tt>.deb</tt> file has been made,
1714 if this is applicable. Usually this will be in the same
1715 format as that specified by the upstream author(s);
1716 however, it may need to be reformatted to fit into the
1717 package management system's format and comparison
1722 The comparison behavior of the package management system
1723 with respect to the <var>upstream_version</var> is
1724 described below. The <var>upstream_version</var>
1725 portion of the version number is mandatory.
1729 The <var>upstream_version</var> may contain only
1732 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1734 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1735 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1736 start with a digit. If there is no
1737 <var>debian_revision</var> then hyphens are not allowed;
1738 if there is no <var>epoch</var> then colons are not
1742 <tag><var>debian_revision</var></tag>
1746 This part of the version number specifies the version of
1747 the Debian package based on the upstream version. It
1748 may contain only alphanumerics and the characters
1749 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1750 compared in the same way as the
1751 <var>upstream_version</var> is.
1755 It is optional; if it isn't present then the
1756 <var>upstream_version</var> may not contain a hyphen.
1757 This format represents the case where a piece of
1758 software was written specifically to be turned into a
1759 Debian package, and so there is only one `debianization'
1760 of it and therefore no revision indication is required.
1764 It is conventional to restart the
1765 <var>debian_revision</var> at <tt>1</tt> each time the
1766 <var>upstream_version</var> is increased.
1770 The package management system will break the version
1771 number apart at the last hyphen in the string (if there
1772 is one) to determine the <var>upstream_version</var> and
1773 <var>debian_revision</var>. The absence of a
1774 <var>debian_revision</var> compares earlier than the
1775 presence of one (but note that the
1776 <var>debian_revision</var> is the least significant part
1777 of the version number).
1781 The <var>upstream_version</var> and <var>debian_revision</var>
1782 parts are compared by the package management system using the
1787 The strings are compared from left to right.
1791 First the initial part of each string consisting entirely of
1792 non-digit characters is determined. These two parts (one of
1793 which may be empty) are compared lexically. If a difference
1794 is found it is returned. The lexical comparison is a
1795 comparison of ASCII values modified so that all the letters
1796 sort earlier than all the non-letters.
1800 Then the initial part of the remainder of each string which
1801 consists entirely of digit characters is determined. The
1802 numerical values of these two parts are compared, and any
1803 difference found is returned as the result of the comparison.
1804 For these purposes an empty string (which can only occur at
1805 the end of one or both version strings being compared) counts
1810 These two steps (comparing and removing initial non-digit
1811 strings and initial digit strings) are repeated until a
1812 difference is found or both strings are exhausted.
1816 Note that the purpose of epochs is to allow us to leave behind
1817 mistakes in version numbering, and to cope with situations
1818 where the version numbering scheme changes. It is
1819 <em>not</em> intended to cope with version numbers containing
1820 strings of letters which the package management system cannot
1821 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1822 silly orderings (the author of this manual has heard of a
1823 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1824 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1825 <tt>2</tt> and so forth).
1829 If an upstream package has problematic version numbers they
1830 should be converted to a sane form for use in the
1831 <tt>Version</tt> field.
1835 <heading>Version numbers based on dates</heading>
1837 In general, Debian packages should use the same version
1838 numbers as the upstream sources.</p>
1841 However, in some cases where the upstream version number is
1842 based on a date (e.g., a development `snapshot' release) the
1843 package management system cannot handle these version
1844 numbers without epochs. For example, dpkg will consider
1845 `96May01' to be greater than `96Dec24'.</p>
1848 To prevent having to use epochs for every new upstream
1849 version, the version number should be changed to the
1850 following format in such cases: `19960501', `19961224'. It
1851 is up to the maintainer whether he/she wants to bother the
1852 upstream maintainer to change the version numbers upstream,
1856 Note that other version formats based on dates which are
1857 parsed correctly by the package management system should
1858 <em>not</em> be changed.</p>
1861 Native Debian packages (i.e., packages which have been
1862 written especially for Debian) whose version numbers include
1863 dates should always use the `YYYYMMDD' format.</p>
1867 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1869 <sect id="timestamps"><heading>Time Stamps</heading>
1871 Maintainers should preserve the modification times of the
1872 upstream source files in a package, as far as is reasonably
1876 The rationale is that there is some information conveyed
1877 by knowing the age of the file, for example, you could
1878 recognize that some documentation is very old by looking
1879 at the modification time, so it would be nice if the
1880 modification time of the upstream source would be
1887 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1888 main building script</heading>
1891 This file must be an executable makefile, and contains the
1892 package-specific recipes for compiling the package and
1893 building binary package(s) from the source.
1897 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1898 so that it can be invoked by saying its name rather than
1899 invoking <prgn>make</prgn> explicitly.
1903 Since an interactive <tt>debian/rules</tt> script makes it
1904 impossible to auto-compile that package and also makes it
1905 hard for other people to reproduce the same binary
1906 package, all <em>required targets</em> MUST be
1907 non-interactive. At a minimum, required targets are the
1908 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1909 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1910 <em>binary-indep</em>, and <em>build</em>. It also follows
1911 that any target that these targets depend on must also be
1916 The required and optional targets are as follows:
1918 <tag><tt>build</tt></tag>
1921 This should perform all non-interactive configuration
1922 and compilation of the package. If a package has an
1923 interactive pre-build configuration routine, the
1924 Debianized source package must either be built after
1925 this has taken place (so that the binary package can
1926 be built without rerunning the configuration) or the
1927 configuration routine modified to become
1928 non-interactive. (The latter is preferable if there
1929 are architecture-specific features detected by the
1930 configuration routine.)
1934 For some packages, notably ones where the same
1935 source tree is compiled in different ways to produce
1936 two binary packages, the <prgn>build</prgn> target
1937 does not make much sense. For these packages it is
1938 good enough to provide two (or more) targets
1939 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1940 for each of the ways of building the package, and a
1941 <prgn>build</prgn> target that does nothing. The
1942 <prgn>binary</prgn> target will have to build the
1943 package in each of the possible ways and make the
1944 binary package out of each.
1948 The <prgn>build</prgn> target must not do anything
1949 that might require root privilege.
1953 The <prgn>build</prgn> target may need to run the
1954 <prgn>clean</prgn> target first - see below.
1958 When a package has a configuration and build routine
1959 which takes a long time, or when the makefiles are
1960 poorly designed, or when <prgn>build</prgn> needs to
1961 run <prgn>clean</prgn> first, it is a good idea to
1962 <tt>touch build</tt> when the build process is
1963 complete. This will ensure that if <tt>debian/rules
1964 build</tt> is run again it will not rebuild the whole
1968 Another common way to do this is for <prgn>build</prgn>
1969 to depend on <prgn>build-stamp</prgn> and to do
1970 nothing else, and for the <prgn>build-stamp</prgn>
1971 target to do the building and to <tt>touch
1972 build-stamp</tt> on completion. This is
1973 especially useful if the build routine creates a
1974 file or directory called <tt>build</tt>; in such a
1975 case, <prgn>build</prgn> will need to be listed as
1976 a phony target (i.e., as a dependency of the
1977 <tt>.PHONY</tt> target). See the documentation of
1978 <prgn>make</prgn> for more information on phony
1985 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1986 <tt>binary-indep</tt>
1990 The <prgn>binary</prgn> target must be all that is
1991 necessary for the user to build the binary package(s)
1992 produced from this source package. All of these
1993 targets are required to be non-interactive. It is
1994 split into two parts: <prgn>binary-arch</prgn> builds
1995 the binary packages which are specific to a particular
1996 architecture, and <prgn>binary-indep</prgn> builds
1997 those which are not.
2001 <prgn>binary</prgn> may be (and commonly is) a target
2002 with no commands which simply depends on
2003 <prgn>binary-arch</prgn> and
2004 <prgn>binary-indep</prgn>.
2008 Each <prgn>binary-*</prgn> target should depend on
2009 the <prgn>build</prgn> target, above, so that the
2010 package is built if it has not been already. It
2011 should then create the relevant binary package(s),
2012 using <prgn>dpkg-gencontrol</prgn> to make their
2013 control files and <prgn>dpkg-deb</prgn> to build
2014 them and place them in the parent of the top level
2019 Both the <prgn>binary-arch</prgn> and
2020 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2021 If one of them has nothing to do (which will always be
2022 the case if the source generates only a single binary
2023 package, whether architecture-dependent or not), it
2024 must still exist and must always succeed.
2028 The <prgn>binary</prgn> targets must be invoked as
2032 The <prgn>fakeroot</prgn> package often allows one
2033 to build a package correctly even without being
2040 <tag><tt>clean</tt></tag>
2044 This must undo any effects that the <prgn>build</prgn>
2045 and <prgn>binary</prgn> targets may have had, except
2046 that it should leave alone any output files created in
2047 the parent directory by a run of a <prgn>binary</prgn>
2048 target. This target must be non-interactive.
2052 If a <prgn>build</prgn> file is touched at the end of
2053 the <prgn>build</prgn> target, as suggested above, it
2054 should be removed as the first action that
2055 <prgn>clean</prgn> performs, so that running
2056 <prgn>build</prgn> again after an interrupted
2057 <prgn>clean</prgn> doesn't think that everything is
2062 The <prgn>clean</prgn> target may need to be
2063 invoked as root if <prgn>binary</prgn> has been
2064 invoked since the last <prgn>clean</prgn>, or if
2065 <prgn>build</prgn> has been invoked as root (since
2066 <prgn>build</prgn> may create directories, for
2071 <tag><tt>get-orig-source</tt> (optional)</tag>
2075 This target fetches the most recent version of the
2076 original source package from a canonical archive site
2077 (via FTP or WWW, for example), does any necessary
2078 rearrangement to turn it into the original source
2079 tar file format described below, and leaves it in the
2084 This target may be invoked in any directory, and
2085 should take care to clean up any temporary files it
2090 This target is optional, but providing it if
2091 possible is a good idea.
2097 The <prgn>build</prgn>, <prgn>binary</prgn> and
2098 <prgn>clean</prgn> targets must be invoked with the current
2099 directory being the package's top-level directory.
2104 Additional targets may exist in <tt>debian/rules</tt>,
2105 either as published or undocumented interfaces or for the
2106 package's internal use.
2110 The architectures we build on and build for are determined
2111 by <prgn>make</prgn> variables using
2112 <prgn>dpkg-architecture</prgn>. You can determine the
2113 Debian architecture and the GNU style architecture
2114 specification string for the build machine (the machine type
2115 we are building on) as well as for the host machine (the
2116 machine type we are building for). Here is a list of
2117 supported <prgn>make</prgn> variables:
2118 <list compact="compact">
2120 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2123 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2124 specification string)</p>
2127 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2128 <tt>DEB_*_GNU_TYPE</tt>)</p>
2131 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2132 <tt>DEB_*_GNU_TYPE</tt>)</p>
2134 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2135 the build machine or <tt>HOST</tt> for specification of the
2140 Backward compatibility can be provided in the rules file
2141 by setting the needed variables to suitable default
2142 values; please refer to the documentation of
2143 <prgn>dpkg-architecture</prgn> for details.
2147 It is important to understand that the <tt>DEB_*_ARCH</tt>
2148 string only determines which Debian architecture we are
2149 building on or for. It should not be used to get the CPU
2150 or system information; the GNU style variables should be
2155 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2159 This file records the changes to the Debian-specific parts of the
2163 Though there is nothing stopping an author who is also
2164 the Debian maintainer from using it for all their
2165 changes, it will have to be renamed if the Debian and
2166 upstream maintainers become different people. In such a
2167 case, however, it might be better to maintain the
2168 package as a non-native package.
2174 It has a special format which allows the package building
2175 tools to discover which version of the package is being
2176 built and find out other release-specific information.
2180 That format is a series of entries like this:
2182 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2184 * <var>change details</var>
2185 <var>more change details</var>
2186 * <var>even more change details</var>
2188 -- <var>maintainer name and email address</var> <var>date</var>
2193 <var>package</var> and <var>version</var> are the source
2194 package name and version number.
2198 <var>distribution(s)</var> lists the distributions where
2199 this version should be installed when it is uploaded - it
2200 is copied to the <tt>Distribution</tt> field in the
2201 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2205 <var>urgency</var> is the value for the <tt>Urgency</tt>
2206 field in the <tt>.changes</tt> file for the upload. It is
2207 not possible to specify an urgency containing commas; commas
2208 are used to separate
2209 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2210 <prgn>dpkg</prgn> changelog format (though there is
2211 currently only one useful <var>keyword</var>,
2215 Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
2216 <tt>high</tt> and <tt>critical</tt>. They have an
2217 effect on how quickly a package will be considered for
2218 inclusion into the <tt>testing</tt> distribution, and
2219 give an indication of the importance of any fixes
2220 included in this upload.
2226 The change details may in fact be any series of lines
2227 starting with at least two spaces, but conventionally each
2228 change starts with an asterisk and a separating space and
2229 continuation lines are indented so as to bring them in
2230 line with the start of the text above. Blank lines may be
2231 used here to separate groups of changes, if desired.
2235 If this upload resolves bugs recorded in the Bug Tracking
2236 System (BTS), they may be automatically closed on the
2237 inclusion of this package into the Debian archive by
2238 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2239 in the change details.
2242 To be precise, the string should match the following
2243 Perl regular expression:
2245 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2247 Then all of the bug numbers listed will be closed by the
2248 archive maintenance script (<prgn>katie</prgn>), or in
2249 the case of an NMU, marked as fixed.
2255 The maintainer name and email address used in the changelog
2256 should be the details of the person uploading <em>this</em>
2257 version. They are <em>not</em> necessarily those of the
2258 usual package maintainer. The information here will be
2259 copied to the <tt>Changed-By</tt> field in the
2260 <tt>.changes</tt> file, and then later used to send an
2261 acknowledgement when the upload has been installed.
2265 The <var>date</var> should be in RFC822 format
2268 This is generated by the <prgn>822-date</prgn>
2271 </footnote>; it should include the time zone specified
2272 numerically, with the time zone name or abbreviation
2273 optionally present as a comment in parentheses.
2277 The first `title' line with the package name should start
2278 at the left hand margin; the `trailer' line with the
2279 maintainer and date details should be preceded by exactly
2280 one space. The maintainer details and the date must be
2281 separated by exactly two spaces.
2284 <sect1><heading>Defining alternative changelog formats</heading>
2287 It is possible to use a different format to the standard
2288 one, by providing a parser for the format you wish to
2292 A changelog parser must not interact with the user at
2298 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2299 and variable substitutions </heading>
2302 When <prgn>dpkg-gencontrol</prgn>,
2303 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2304 generate control files they perform variable substitutions
2305 on their output just before writing it. Variable
2306 substitutions have the form
2307 <tt>${<var>variable-name</var>}</tt>. The optional file
2308 <tt>debian/substvars</tt> contains variable substitutions to
2309 be used; variables can also be set directly from
2310 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2311 source packaging commands, and certain predefined variables
2316 The <tt>debian/substvars</tt> file is usually generated and
2317 modified dynamically by <tt>debian/rules</tt> targets; in
2318 this case it must be removed by the <prgn>clean</prgn>
2323 See <manref name="dpkg-source" section="1"> for full
2324 details about source variable substitutions, including the
2325 format of <tt>debian/substvars</tt>.</p>
2328 <sect id="debianfiles"><heading><tt>debian/files</tt>
2332 This file is not a permanent part of the source tree; it
2333 is used while building packages to record which files are
2334 being generated. <prgn>dpkg-genchanges</prgn> uses it
2335 when it generates a <tt>.changes</tt> file.
2339 It should not exist in a shipped source package, and so it
2340 (and any backup files or temporary files such as
2344 <tt>files.new</tt> is used as a temporary file by
2345 <prgn>dpkg-gencontrol</prgn> and
2346 <prgn>dpkg-distaddfile</prgn> - they write a new
2347 version of <tt>files</tt> here before renaming it,
2348 to avoid leaving a corrupted copy if an error
2351 </footnote>) should be removed by the
2352 <prgn>clean</prgn> target. It may also be wise to
2353 ensure a fresh start by emptying or removing it at the
2354 start of the <prgn>binary</prgn> target.
2358 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2359 package, it adds an entry to <tt>debian/files</tt> for the
2360 <tt>.deb</tt> file that will be created when <prgn>dpkg-deb
2361 --build</prgn> is run for that binary package. So for most
2362 packages all that needs to be done with this file is to
2363 delete it in the <prgn>clean</prgn> target.
2367 If a package upload includes files besides the source
2368 package and any binary packages whose control files were
2369 made with <prgn>dpkg-gencontrol</prgn> then they should be
2370 placed in the parent of the package's top-level directory
2371 and <prgn>dpkg-distaddfile</prgn> should be called to add
2372 the file to the list in <tt>debian/files</tt>.</p>
2375 <sect id="restrictions"><heading>Restrictions on objects in source packages
2379 The source package may not contain any hard links
2382 This is not currently detected when building source
2383 packages, but only when extracting
2387 Hard links may be permitted at some point in the
2388 future, but would require a fair amount of
2391 </footnote>, device special files, sockets or setuid or
2395 Setgid directories are allowed.
2400 <sect id="descriptions"><heading>Descriptions of packages - the
2401 <tt>Description</tt> field </heading>
2404 The description is intended to describe the program to a user
2405 who has never met it before so that they know whether they
2406 want to install it. It should also give information about the
2407 significant dependencies and conflicts between this package
2408 and others, so that the user knows why these dependencies and
2409 conflicts have been declared.
2412 <sect1><heading>Notes about writing descriptions
2416 The single line synopsis should be kept brief - certainly
2417 under 80 characters.
2421 Do not include the package name in the synopsis line. The
2422 display software knows how to display this already, and you
2423 do not need to state it. Remember that in many situations
2424 the user may only see the synopsis line - make it as
2425 informative as you can.
2429 Do not try to continue the single line synopsis into the
2430 extended description. This will not work correctly when
2431 the full description is displayed, and makes no sense
2432 where only the summary (the single line synopsis) is
2437 The extended description should describe what the package
2438 does and how it relates to the rest of the system (in terms
2439 of, for example, which subsystem it is which part of).
2443 The description field needs to make sense to anyone, even
2444 people who have no idea about any of the things the
2448 The blurb that comes with a program in its
2449 announcements and/or <prgn>README</prgn> files is
2450 rarely suitable for use in a description. It is
2451 usually aimed at people who are already in the
2452 community where the package is used.
2458 Put important information first, both in the synopsis and
2459 extended description. Sometimes only the first part of the
2460 synopsis or of the description will be displayed. You can
2461 assume that there will usually be a way to see the whole
2462 extended description.
2466 You may include information about dependencies and so forth
2467 in the extended description, if you wish.
2471 Do not use tab characters. Their effect is not predictable.
2479 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2480 and installation procedure
2483 <sect><heading>Introduction to package maintainer scripts
2487 It is possible to supply scripts as part of a package which
2488 the package management system will run for you when your
2489 package is installed, upgraded or removed.
2493 These scripts are the files <tt>preinst</tt>,
2494 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2495 control area of the package. They must be proper executable
2496 files; if they are scripts (which is recommended), they must
2497 start with the usual <tt>#!</tt> convention. They should be
2498 readable and executable by anyone, and not world-writable.
2502 The package management system looks at the exit status from
2503 these scripts. It is important that they exit with a
2504 non-zero status if there is an error, so that the package
2505 management system can stop its processing. For shell
2506 scripts this means that you <em>almost always</em> need to
2507 use <tt>set -e</tt> (this is usually true when writing shell
2508 scripts, in fact). It is also important, of course, that
2509 they don't exit with a non-zero status if everything went
2514 When a package is upgraded a combination of the scripts from
2515 the old and new packages is called during the upgrade
2516 procedure. If your scripts are going to be at all
2517 complicated you need to be aware of this, and may need to
2518 check the arguments to your scripts.
2522 Broadly speaking the <prgn>preinst</prgn> is called before
2523 (a particular version of) a package is installed, and the
2524 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2525 before (a version of) a package is removed and the
2526 <prgn>postrm</prgn> afterwards.
2530 Programs called from maintainer scripts should not normally
2531 have a path prepended to them. Before installation is
2532 started, the package management system checks to see if the
2533 programs <prgn>ldconfig</prgn>,
2534 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2535 and <prgn>update-rc.d</prgn> can be found via the
2536 <tt>PATH</tt> environment variable. Those programs, and any
2537 other program that one would expect to be on the
2538 <tt>PATH</tt>, should thus be invoked without an absolute
2539 pathname. Maintainer scripts should also not reset the
2540 <tt>PATH</tt>, though they might choose to modify it by
2541 prepending or appending package-specific directories. These
2542 considerations really apply to all shell scripts.</p>
2546 <heading>Maintainer scripts Idempotency</heading>
2549 It is necessary for the error recovery procedures that the
2550 scripts be idempotent. This means that if it is run
2551 successfully, and then it is called again, it doesn't bomb
2552 out or cause any harm, but just ensures that everything is
2553 the way it ought to be. If the first call failed, or
2554 aborted half way through for some reason, the second call
2555 should merely do the things that were left undone the first
2556 time, if any, and exit with a success status if everything
2560 This is so that if an error occurs, the user interrupts
2561 <prgn>dpkg</prgn> or some other unforeseen circumstance
2562 happens you don't leave the user with a badly-broken
2563 package when <prgn>dpkg</prgn> attempts to repeat the
2571 <heading>Controlling terminal for maintainer scripts</heading>
2574 The maintainer scripts are guaranteed to run with a
2575 controlling terminal and can interact with the user.
2576 If they need to prompt for passwords, do full-screen
2577 interaction or something similar you should do these
2578 things to and from <tt>/dev/tty</tt>, since
2579 <prgn>dpkg</prgn> will at some point redirect scripts'
2580 standard input and output so that it can log the
2581 installation process. Likewise, because these scripts
2582 may be executed with standard output redirected into a
2583 pipe for logging purposes, Perl scripts should set
2584 unbuffered output by setting <tt>$|=1</tt> so that the
2585 output is printed immediately rather than being
2590 Each script should return a zero exit status for
2591 success, or a nonzero one for failure.
2595 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2600 <list compact="compact">
2602 <p><var>new-preinst</var> <tt>install</tt></p>
2605 <p><var>new-preinst</var> <tt>install</tt>
2606 <var>old-version</var></p>
2609 <p><var>new-preinst</var> <tt>upgrade</tt>
2610 <var>old-version</var></p>
2613 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2614 <var>new-version</var>
2620 <list compact="compact">
2622 <p><var>postinst</var> <tt>configure</tt>
2623 <var>most-recently-configured-version</var></p>
2626 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2627 <var>new-version</var></p>
2630 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2631 <tt>in-favour</tt> <var>package</var>
2632 <var>new-version</var></p>
2636 <var>deconfigured's-postinst</var>
2637 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2638 <var>failed-install-package</var> <var>version</var>
2639 <tt>removing</tt> <var>conflicting-package</var>
2646 <list compact="compact">
2648 <p><var>prerm</var> <tt>remove</tt></p>
2651 <p><var>old-prerm</var> <tt>upgrade</tt>
2652 <var>new-version</var></p>
2655 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2656 <var>old-version</var></p>
2659 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2660 <tt>in-favour</tt> <var>package</var>
2661 <var>new-version</var></p>
2665 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2666 <tt>in-favour</tt> <var>package-being-installed</var>
2667 <var>version</var> <tt>removing</tt>
2668 <var>conflicting-package</var>
2675 <list compact="compact">
2677 <p><var>postrm</var> <tt>remove</tt></p>
2680 <p><var>postrm</var> <tt>purge</tt></p>
2684 <var>old-postrm</var> <tt>upgrade</tt>
2685 <var>new-version</var></p>
2688 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2689 <var>old-version</var></p>
2692 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2695 <p><var>new-postrm</var> <tt>abort-install</tt>
2696 <var>old-version</var></p>
2699 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2700 <var>old-version</var></p>
2704 <var>disappearer's-postrm</var> <tt>disappear</tt>
2705 <var>overwriter</var>
2706 <var>overwriter-version</var></p></item>
2711 <sect id="unpackphase"><heading>Details of unpack phase of
2712 installation or upgrade
2716 The procedure on installation/upgrade/overwrite/disappear
2717 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2718 stage of <tt>dpkg --install</tt>) is as follows. In each
2719 case, if a major error occurs (unless listed below) the
2720 actions are, in general, run backwards - this means that the
2721 maintainer scripts are run with different arguments in
2722 reverse order. These are the `error unwind' calls listed
2730 <p>If a version of the package is already
2733 <var>old-prerm</var> upgrade <var>new-version</var>
2738 If the script runs but exits with a non-zero
2739 exit status, <prgn>dpkg</prgn> will attempt:
2741 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2743 Error unwind, for both the above cases:
2745 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2753 <p>If a `conflicting' package is being removed at the same time:
2757 If any packages depended on that conflicting
2758 package and <tt>--auto-deconfigure</tt> is
2759 specified, call, for each such package:
2761 <var>deconfigured's-prerm</var> deconfigure \
2762 in-favour <var>package-being-installed</var> <var>version</var> \
2763 removing <var>conflicting-package</var> <var>version</var>
2767 <var>deconfigured's-postinst</var> abort-deconfigure \
2768 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2769 removing <var>conflicting-package</var> <var>version</var>
2771 The deconfigured packages are marked as
2772 requiring configuration, so that if
2773 <tt>--install</tt> is used they will be
2774 configured again if possible.</p>
2777 <p>To prepare for removal of the conflicting package, call:
2779 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2783 <var>conflictor's-postinst</var> abort-remove \
2784 in-favour <var>package</var> <var>new-version</var>
2795 <p>If the package is being upgraded, call:
2797 <var>new-preinst</var> upgrade <var>old-version</var>
2802 Otherwise, if the package had some configuration
2803 files from a previous version installed (i.e., it
2804 is in the `configuration files only' state):
2806 <var>new-preinst</var> install <var>old-version</var>
2810 <p>Otherwise (i.e., the package was completely purged):
2812 <var>new-preinst</var> install
2814 Error unwind actions, respectively:
2816 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2817 <var>new-postrm</var> abort-install <var>old-version</var>
2818 <var>new-postrm</var> abort-install
2828 The new package's files are unpacked, overwriting any
2829 that may be on the system already, for example any
2830 from the old version of the same package or from
2831 another package. Backups of the old files are kept
2832 temporarily, and if anything goes wrong the package
2833 management system will attempt to put them back as
2834 part of the error unwind.
2838 It is an error for a package to contains files which
2839 are on the system in another package, unless
2840 <tt>Replaces</tt> is used (see <ref id="replaces">).
2842 The following paragraph is not currently the case:
2843 Currently the <tt>- - force-overwrite</tt> flag is
2844 enabled, downgrading it to a warning, but this may not
2850 It is a more serious error for a package to contain a
2851 plain file or other kind of non-directory where another
2852 package has a directory (again, unless
2853 <tt>Replaces</tt> is used). This error can be
2854 overridden if desired using
2855 <tt>--force-overwrite-dir</tt>, but this is not
2860 Packages which overwrite each other's files produce
2861 behavior which, though deterministic, is hard for the
2862 system administrator to understand. It can easily
2863 lead to `missing' programs if, for example, a package
2864 is installed which overwrites a file from another
2865 package, and is then removed again.
2868 Part of the problem is due to what is arguably a
2869 bug in <prgn>dpkg</prgn>.
2875 A directory will never be replaced by a symbolic link
2876 to a directory or vice versa; instead, the existing
2877 state (symlink or not) will be left alone and
2878 <prgn>dpkg</prgn> will follow the symlink if there is
2886 <p>If the package is being upgraded, call
2888 <var>old-postrm</var> upgrade <var>new-version</var>
2892 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2894 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2896 Error unwind, for both cases:
2898 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2904 This is the point of no return - if
2905 <prgn>dpkg</prgn> gets this far, it won't back off
2906 past this point if an error occurs. This will
2907 leave the package in a fairly bad state, which
2908 will require a successful re-installation to clear
2909 up, but it's when <prgn>dpkg</prgn> starts doing
2910 things that are irreversible.
2915 Any files which were in the old version of the package
2916 but not in the new are removed.</p>
2919 <p>The new file list replaces the old.</p>
2922 <p>The new maintainer scripts replace the old.</p>
2926 <p>Any packages all of whose files have been overwritten during the
2927 installation, and which aren't required for
2928 dependencies, are considered to have been removed.
2929 For each such package
2932 <p><prgn>dpkg</prgn> calls:
2934 <var>disappearer's-postrm</var> disappear \
2935 <var>overwriter</var> <var>overwriter-version</var>
2940 <p>The package's maintainer scripts are removed.
2945 It is noted in the status database as being in a
2946 sane state, namely not installed (any conffiles
2947 it may have are ignored, rather than being
2948 removed by <prgn>dpkg</prgn>). Note that
2949 disappearing packages do not have their prerm
2950 called, because <prgn>dpkg</prgn> doesn't know
2951 in advance that the package is going to
2960 Any files in the package we're unpacking that are also
2961 listed in the file lists of other packages are removed
2962 from those lists. (This will lobotomize the file list
2963 of the `conflicting' package if there is one.)
2968 The backup files made during installation, above, are
2975 The new package's status is now sane, and recorded as
2980 Here is another point of no return - if the
2981 conflicting package's removal fails we do not unwind
2982 the rest of the installation; the conflicting package
2983 is left in a half-removed limbo.
2989 If there was a conflicting package we go and do the
2990 removal actions (described below), starting with the
2991 removal of the conflicting package's files (any that
2992 are also in the package being installed have already
2993 been removed from the conflicting package's file list,
2994 and so do not get removed now).
3001 <sect><heading>Details of configuration</heading>
3004 When we configure a package (this happens with <tt>dpkg
3005 --install</tt>, or with <tt>--configure</tt>), we first
3006 update any <tt>conffile</tt>s and then call:
3008 <var>postinst</var> configure <var>most-recently-configured-version</var>
3013 No attempt is made to unwind after errors during
3018 If there is no most recently configured version
3019 <prgn>dpkg</prgn> will pass a null argument; older versions
3020 of dpkg may pass <tt><unknown></tt> (including the
3021 angle brackets) in this case. Even older ones do not pass a
3022 second argument at all, under any circumstances.
3026 <sect><heading>Details of removal and/or configuration purging
3034 <var>prerm</var> remove
3040 The package's files are removed (except <tt>conffile</tt>s).
3045 <var>postrm</var> remove
3050 All the maintainer scripts except the <tt>postrm</tt>
3055 If we aren't purging the package we stop here. Note
3056 that packages which have no <tt>postrm</tt> and no
3057 <tt>conffile</tt>s are automatically purged when
3058 removed, as there is no difference except for the
3059 <prgn>dpkg</prgn> status.</p>
3063 The conffiles and any backup files (<tt>~</tt>-files,
3064 <tt>#*#</tt> files, <tt>%</tt>-files,
3065 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3069 <var>postrm</var> purge
3073 <p>The package's file list is removed.</p>
3076 No attempt is made to unwind after errors during
3083 <chapt id="relationships"><heading>Declaring relationships between
3087 Packages can declare in their control file that they have
3088 certain relationships to other packages - for example, that
3089 they may not be installed at the same time as certain other
3090 packages, and/or that they depend on the presence of others,
3091 or that they should overwrite files in certain other packages
3096 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3097 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3098 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3102 Source packages may declare relationships to binary packages,
3103 saying that they require certain binary packages to be
3104 installed or absent at the time of building the package.
3108 This is done using the <tt>Build-Depends</tt>,
3109 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3110 <tt>Build-Conflicts-Indep</tt> control file fields.
3113 <sect id="depsyntax"><heading>Syntax of relationship fields
3117 These fields all have a uniform syntax. They are a list of
3118 package names separated by commas.
3122 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3123 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3124 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3125 control file fields of the package, which declare
3126 dependencies on other packages, the package names listed may
3127 also include lists of alternative package names, separated
3128 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3129 a case, the presence of any one of the alternative packages
3130 is installed, that part of the dependency is considered to
3135 All the fields except <tt>Provides</tt> may restrict their
3136 applicability to particular versions of each named package.
3137 This is done in parentheses after each individual package
3138 name; the parentheses should contain a relation from the
3139 list below followed by a version number, in the format
3140 described in <ref id="versions">.
3144 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3145 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3146 strictly earlier, earlier or equal, exactly equal, later or
3147 equal and strictly later, respectively. The forms
3148 <tt><</tt> and <tt>></tt> were used to mean
3149 earlier/later or equal, rather than strictly earlier/later,
3150 so they should not appear in new packages (though
3151 <prgn>dpkg</prgn> still supports them).
3155 Whitespace may appear at any point in the version
3156 specification, and must appear where it's necessary to
3157 disambiguate; it is not otherwise significant. For
3158 consistency and in case of future changes to
3159 <prgn>dpkg</prgn> it is recommended that a single space be
3160 used after a version relationship and before a version
3161 number; it is usual also to put a single space after each
3162 comma, on either side of each vertical bar, and before each
3171 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3176 All fields that specify build-time relationships
3177 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3178 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3179 may be restricted to a certain set of architectures. This
3180 is done in brackets after each individual package name and
3181 the optional version specification. The brackets enclose a
3182 list of Debian architecture names separated by whitespace.
3183 Exclamation marks may be prepended to each of the names.
3184 (It is not permitted for some names to be prepended with
3185 exclamation marks and others not.) If the current Debian
3186 host architecture is not in this list and there are no
3187 exclamation marks in the list, or it is in the list with a
3188 prepended exclamation mark, the package name and the
3189 associated version specification are ignored completely for
3190 the purposes of defining the relationships.
3197 Build-Depends-Indep: texinfo
3198 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3199 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3205 <heading>Binary Dependencies - <tt>Depends</tt>,
3206 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3207 <tt>Pre-Depends</tt>
3211 These five fields are used to declare a dependency
3212 relationship by one package on another. They appear in the
3213 depending package's control file.
3217 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3218 (discussed below) take effect <em>only</em> when a package
3219 is to be configured. They do not prevent a package being on
3220 the system in an unconfigured state while its dependencies
3221 are unsatisfied, and it is possible to replace a package
3222 whose dependencies are satisfied and which is properly
3223 installed with a different version whose dependencies are
3224 not and cannot be satisfied; when this is done the depending
3225 package will be left unconfigured (since attempts to
3226 configure it will give errors) and will not function
3231 For this reason packages in an installation run are usually
3232 all unpacked first and all configured later; this gives
3233 later versions of packages with dependencies on later
3234 versions of other packages the opportunity to have their
3235 dependencies satisfied.
3239 Thus <tt>Depends</tt> allows package maintainers to impose
3240 an order in which packages should be configured.
3242 <tag><tt>Depends</tt></tag>
3245 <p>This declares an absolute dependency.
3249 The <tt>Depends</tt> field should be used if the
3250 depended-on package is required for the depending
3251 package to provide a significant amount of
3255 <tag><tt>Recommends</tt></tag>
3257 <p>This declares a strong, but not absolute, dependency.
3261 The <tt>Recommends</tt> field should list packages
3262 that would be found together with this one in all but
3263 unusual installations.</p>
3266 <tag><tt>Suggests</tt></tag>
3270 This is used to declare that one package may be more
3271 useful with one or more others. Using this field
3272 tells the packaging system and the user that the
3273 listed packages are related to this one and can
3274 perhaps enhance its usefulness, but that installing
3275 this one without them is perfectly reasonable.
3279 <tag><tt>Enhances</tt></tag>
3282 This field is similar to Suggests but works in the
3283 opposite direction. It is used to declare that a
3284 package can enhance the functionality of another
3289 <tag><tt>Pre-Depends</tt></tag>
3293 This field is like <tt>Depends</tt>, except that it
3294 also forces <prgn>dpkg</prgn> to complete installation
3295 of the packages named before even starting the
3296 installation of the package which declares the
3301 <tt>Pre-Depends</tt> should be used sparingly,
3302 preferably only by packages whose premature upgrade or
3303 installation would hamper the ability of the system to
3304 continue with any upgrade that might be in progress.
3308 When the package declaring it is being configured, a
3309 <tt>Pre-Dependency</tt> will be considered satisfied
3310 only if the depending package has been correctly
3311 configured, just as if an ordinary <tt>Depends</tt>
3316 However, when a package declaring a Pre-dependency is
3317 being unpacked the predependency can be satisfied even
3318 if the depended-on package(s) are only unpacked or
3319 half-configured, provided that they have been
3320 configured correctly at some point in the past (and
3321 not removed or partially removed since). In this case
3322 both the previously-configured and currently unpacked
3323 or half-configured versions must satisfy any version
3324 clause in the <tt>Pre-Depends</tt> field.
3330 When selecting which level of dependency to use you should
3331 consider how important the depended-on package is to the
3332 functionality of the one declaring the dependency. Some
3333 packages are composed of components of varying degrees of
3334 importance. Such a package should list using
3335 <tt>Depends</tt> the package(s) which are required by the
3336 more important components. The other components'
3337 requirements may be mentioned as Suggestions or
3338 Recommendations, as appropriate to the components' relative
3343 <sect id="conflicts"><heading>Alternative binary packages -
3344 <tt>Conflicts</tt> and <tt>Replaces</tt>
3348 When one binary package declares a conflict with another
3349 <prgn>dpkg</prgn> will refuse to allow them to be installed
3350 on the system at the same time.
3354 If one package is to be installed, the other must be removed
3355 first - if the package being installed is marked as
3356 replacing (<ref id="replaces">) the one on the system, or
3357 the one on the system is marked as deselected, or both
3358 packages are marked <tt>Essential</tt>, then
3359 <prgn>dpkg</prgn> will automatically remove the package
3360 which is causing the conflict, otherwise it will halt the
3361 installation of the new package with an error. This
3362 mechanism specifically doesn't work when the installed
3363 package is <tt>Essential</tt>, but the new package is not.
3368 A package will not cause a conflict merely because its
3369 configuration files are still installed; it must be at least
3374 A special exception is made for packages which declare a
3375 conflict with their own package name, or with a virtual
3376 package which they provide (see below): this does not
3377 prevent their installation, and allows a package to conflict
3378 with others providing a replacement for it. You use this
3379 feature when you want the package in question to be the only
3380 package providing something.
3384 A <tt>Conflicts</tt> entry should almost never have an
3385 `earlier than' version clause. This would prevent
3386 <prgn>dpkg</prgn> from upgrading or installing the package
3387 which declared such a conflict until the upgrade or removal
3388 of the conflicted-with package had been completed.
3392 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3396 As well as the names of actual (`concrete') packages, the
3397 package relationship fields <tt>Depends</tt>,
3398 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3399 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3400 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3401 mention virtual packages.
3405 A virtual package is one which appears in the
3406 <tt>Provides</tt> control file field of another package.
3407 The effect is as if the package(s) which provide a
3408 particular virtual package name had been listed by name
3409 everywhere the virtual package name appears.
3413 If there are both a real and a virtual package of the same
3414 name then the dependency may be satisfied (or the conflict
3415 caused) by either the real package or any of the virtual
3416 packages which provide it. This is so that, for example,
3422 and someone else releases an xemacs package they can say
3426 </example> and all will work in the interim (until a purely
3427 virtual package name is decided on and the <tt>emacs</tt>
3428 and <tt>vm</tt> packages are changed to use it).
3432 If a dependency or a conflict has a version number attached
3433 then only real packages will be considered to see whether
3434 the relationship is satisfied (or the prohibition violated,
3435 for a conflict) - it is assumed that a real package which
3436 provides the virtual package is not of the `right' version.
3437 So, a <tt>Provides</tt> field may not contain version
3438 numbers, and the version number of the concrete package
3439 which provides a particular virtual package will not be
3440 looked at when considering a dependency on or conflict with
3441 the virtual package name.
3445 It is likely that the ability will be added in a future
3446 release of <prgn>dpkg</prgn> to specify a version number for
3447 each virtual package it provides. This feature is not yet
3448 present, however, and is expected to be used only
3453 If you want to specify which of a set of real packages should be the
3454 default to satisfy a particular dependency on a virtual package, you
3455 should list the real package as an alternative before the virtual.
3460 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3461 files and replacing packages
3465 The <tt>Replaces</tt> control file field has two purposes,
3466 which come into play in different situations.
3470 Virtual packages (<ref id="virtual">) are not considered
3471 when looking at a <tt>Replaces</tt> field - the packages
3472 declared as being replaced must be mentioned by their real
3476 <sect1><heading>Overwriting files in other packages
3480 Firstly, as mentioned before, it is usually an error for a
3481 package to contain files which are on the system in
3482 another package, though currently the
3483 <tt>--force-overwrite</tt> flag is enabled by default,
3484 downgrading the error to a warning,
3488 If the overwriting package declares that it replaces the
3489 one containing the file being overwritten then
3490 <prgn>dpkg</prgn> will proceed, and replace the file from
3491 the old package with that from the new. The file will no
3492 longer be listed as `owned' by the old package.
3496 If a package is completely replaced in this way, so that
3497 <prgn>dpkg</prgn> does not know of any files it still
3498 contains, it is considered to have disappeared. It will
3499 be marked as not wanted on the system (selected for
3500 removal) and not installed. Any conffiles details noted
3501 in the package will be ignored, as they will have been
3502 taken over by the replacing package(s). The package's
3503 <prgn>postrm</prgn> script will be run to allow the
3504 package to do any final cleanup required. See <ref
3505 id="mscriptsinstact">.
3509 In the future <prgn>dpkg</prgn> will discard files which
3510 would overwrite those from an already installed package
3511 which declares that it replaces the package being
3512 installed. This is so that you can install an older
3513 version of a package without problems.
3517 This usage of <tt>Replaces</tt> only takes effect when
3518 both packages are at least partially on the system at
3519 once, so that it can only happen if they do not conflict
3520 or if the conflict has been overridden.</p>
3523 <sect1><heading>Replacing whole packages, forcing their
3528 Secondly, <tt>Replaces</tt> allows the packaging system to
3529 resolve which package should be removed when there is a
3530 conflict - see <ref id="conflicts">. This usage only
3531 takes effect when the two packages <em>do</em> conflict,
3532 so that the two effects do not interfere with each other.
3537 <sect><heading>Relationships between source and binary packages -
3538 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3539 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3543 A source package may declare a dependency or a conflict on a
3544 binary package. This is done with the control file fields
3545 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3546 <tt>Build-Conflicts</tt>, and
3547 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3548 the dependencies and conflicts they define must be satisfied
3549 (as defined earlier for binary packages), when one of the
3550 targets in <tt>debian/rules</tt> that the particular field
3551 applies to is invoked.
3554 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3557 The <tt>Build-Depends</tt> and
3558 <tt>Build-Conflicts</tt> fields apply to the targets
3559 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3560 and <tt>binary-indep</tt>.
3563 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3566 The <tt>Build-Depends-Indep</tt> and
3567 <tt>Build-Conflicts-Indep</tt> fields apply to the
3568 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3579 <chapt id="conffiles"><heading>Configuration file handling
3583 <prgn>dpkg</prgn> can do a certain amount of automatic
3584 handling of package configuration files.
3588 Whether this mechanism is appropriate depends on a number of
3589 factors, but basically there are two approaches to any
3590 particular configuration file.
3594 The easy method is to ship a best-effort configuration in the
3595 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3596 handle updates. If the user is unlikely to want to edit the
3597 file, but you need them to be able to without losing their
3598 changes, and a new package with a changed version of the file
3599 is only released infrequently, this is a good approach.
3603 The hard method is to build the configuration file from
3604 scratch in the <prgn>postinst</prgn> script, and to take the
3605 responsibility for fixing any mistakes made in earlier
3606 versions of the package automatically. This will be
3607 appropriate if the file is likely to need to be different on
3612 <chapt id="sharedlibs"><heading>Shared libraries
3616 Packages containing shared libraries must be constructed with
3617 a little care to make sure that the shared library is always
3618 available. This is especially important for packages whose
3619 shared libraries are vitally important, such as the libc.
3623 Firstly, your package should install the shared libraries
3624 under their normal names. For example, the
3625 <prgn>libgdbm1</prgn> package should install
3626 <tt>libgdbm.so.1.7.3</tt> as
3627 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3628 renamed or re-linked by any prerm or postrm scripts;
3629 <prgn>dpkg</prgn> will take care of renaming things safely
3630 without affecting running programs, and attempts to interfere
3631 with this are likely to lead to problems.
3635 Secondly, your package should include the symlink that
3636 <prgn>ldconfig</prgn> would create for the shared libraries.
3637 For example, the <prgn>libgdbm1</prgn> package should include
3638 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3639 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3640 <prgn>ld.so</prgn> can find the library in between the time
3641 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3642 in the <prgn>postinst</prgn> script. Furthermore, older
3643 versions of the package management system required the library
3644 must be placed before the symlink pointing to it in the
3645 <tt>.deb</tt> file. This is so that by the time
3646 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3647 the previous symlink pointing at an older version of the
3648 library) the new shared library is already in place.
3649 Unfortunately, this was not not always possible, since it
3650 highly depends on the behavior of the file system. Some
3651 file systems (such as reiserfs) will reorder the files so it
3652 doesn't matter in what order you create them. Starting with
3653 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3654 files itself when building a package.
3658 Thirdly, the development package should contain a symlink for
3659 the shared library without a version number. For example, the
3660 <tt>libgdbm1-dev</tt> package should include a symlink from
3661 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3662 symlink is needed by <prgn>ld</prgn> when compiling packages
3663 as it will only look for <tt>libgdm.so</tt> and
3664 <tt>libgdm.a</tt> when compiling dynamically or statically,
3669 Any package installing shared libraries in a directory that's listed
3670 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3671 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3672 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3673 script if and only if the first argument is `configure'. However, it
3674 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3675 scripts in the case where the package is being upgraded (see <ref
3676 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3677 that <prgn>dpkg</prgn> uses for the files while it is
3678 installing them and will make the shared library links point
3679 to them, just before <prgn>dpkg</prgn> continues the
3680 installation and removes the links!
3683 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3687 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3688 required when your package provides shared libraries.
3692 Each line is of the form:
3694 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3699 <var>library-name</var> is the name of the shared library,
3700 for example <tt>libc5</tt>.
3704 <var>version-or-soname</var> is the soname of the library -
3705 i.e., the thing that must exactly match for the library to be
3706 recognized by <prgn>ld.so</prgn>. Usually this is the major
3707 version number of the library.
3711 <var>dependencies</var> has the same syntax as a dependency
3712 field in a binary package control file. It should give
3713 details of which package(s) are required to satisfy a binary
3714 built against the version of the library contained in the
3715 package. See <ref id="depsyntax">.
3719 For example, if the package <tt>foo</tt> contains
3720 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3721 <tt>libfoo.so.1</tt>, and the first version of the package
3722 which contained a minor number of at least <tt>2.3</tt> was
3723 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3726 libfoo 1 foo (>= 1.2.3-1)
3731 The version-specific dependency is to avoid warnings from
3732 <prgn>ld.so</prgn> about using older shared libraries with
3736 <sect><heading>Further Technical information on
3737 <tt>shlibs</tt></heading>
3739 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3743 The <tt>debian/shlibs</tt> file provides a way of checking
3744 for shared library dependencies on packaged binaries.
3745 They are intended to be used by package maintainers to
3746 make their lives easier.
3750 Other <tt>shlibs</tt> files that exist on a Debian system are
3752 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3753 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3754 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3755 <item> <p><tt>debian/shlibs.local</tt></p></item>
3757 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3758 creating a binary package.</p>
3761 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3765 <prgn>dpkg-shlibdeps</prgn>
3766 determines the shared libraries directly
3769 It used to do this by calling <prgn>ldd</prgn>, but it
3770 now calls <prgn>objdump</prgn> to do this. This
3771 requires a couple of changes in the way that packages
3775 A binary <tt>foo</tt> directly uses a library
3776 <tt>libbar</tt> if it is linked with that
3777 library. Other libraries that are needed by
3778 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3779 and the dynamic linker will load them automatically
3780 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3781 lists all of the libraries used, both directly and
3782 indirectly; but <prgn>objdump</prgn> only lists the
3783 directly linked libraries. A package only needs to
3784 depend on the libraries it is directly linked to,
3785 since the dependencies for those libraries should
3786 automatically pull in the other libraries.
3789 This change does mean a change in the way packages are
3790 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3791 only run on binaries. But since we will now rely on the
3792 libraries depending on the libraries they themselves
3793 need, the packages containing those libraries will
3794 need to run <prgn>dpkg-shlibdeps</prgn> on the
3798 A good example where this would help us is the current
3799 mess with multiple version of the <tt>mesa</tt>
3800 library. With the <prgn>ldd</prgn>-based system, every
3801 package that uses <tt>mesa</tt> needs to add a
3802 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3803 to handle the glide <tt>mesa</tt> variant. With an
3804 <prgn>objdump</prgn>-based system this isn't necessary
3805 anymore and would have saved everyone a lot of work.
3808 Another example: we could update <tt>libimlib</tt>
3809 with a new version that supports a new graphics format
3810 called dgf. If we use the old <prgn>ldd</prgn> method,
3811 every package that uses <tt>libimlib</tt> would need
3812 to be recompiled so it would also depend on
3813 <tt>libdgf</tt> or it wouldn't run due to missing
3814 symbols. However with the new system, packages using
3815 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3816 having the dependency on <tt>libdgf</tt> and wouldn't
3820 used by the compiled binaries and libraries passed through
3821 on its command line.
3825 For each shared library linked to,
3826 <prgn>dpkg-shlibdeps</prgn> needs to know
3827 <list compact="compact">
3828 <item><p>the package containing the library, and</p></item>
3829 <item><p>the library version number,</p></item>
3831 and it scans the following files in this order:
3832 <enumlist compact="compact">
3833 <item><p><tt>debian/shlibs.local</tt></p></item>
3834 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3835 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3836 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3841 <sect1><heading><em>Who</em> maintains the various
3842 <tt>shlibs</tt> files?
3846 <list compact="compact">
3848 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3853 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3854 - the maintainer of each package</p>
3858 <tt>/etc/dpkg/shlibs.override</tt> - the local
3859 system administrator</p>
3862 <p><tt>debian/shlibs.local</tt> - the maintainer of
3867 The <tt>shlibs.default</tt> file is managed by
3868 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3869 that are provided by <prgn>dpkg</prgn> are just there to
3870 fix things until the shared library packages all have
3871 <tt>shlibs</tt> files.
3875 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3876 the <tt>shlibs</tt> files
3879 <sect2><heading>If your package doesn't provide a shared
3884 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3885 <tt>debian/rules</tt> file. If your package contains
3886 only binaries (e.g. no scripts) use:
3888 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3890 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3891 done. If it does complain you might need to create your
3892 own <tt>debian/shlibs.local</tt> file.</p>
3895 <sect2><heading>If your package provides a shared library
3899 Create a <tt>debian/shlibs</tt> file and let
3900 <tt>debian/rules</tt> install it in the control area:
3902 install -m644 debian/shlibs debian/tmp/DEBIAN
3904 If your package contains additional binaries see above.
3909 <sect1><heading><em>How</em> to write
3910 <tt>debian/shlibs.local</tt>
3914 This file is intended only as a <em>temporary</em> fix if
3915 your binaries depend on a library which doesn't provide
3916 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3920 Let's assume you are packaging a binary <tt>foo</tt>. Your
3921 output in building the package might look like this.
3924 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3925 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3926 libc.so.6 => /lib/libc.so.6 (0x40114000)
3927 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3929 And when you ran <prgn>dpkg-shlibdeps</prgn>
3931 $ dpkg-shlibdeps -O foo
3932 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3933 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3934 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3936 The <prgn>foo</prgn> binary depends on the
3937 <prgn>libbar</prgn> shared library, but no package seems
3938 to provide a <tt>*.shlibs</tt> file in
3939 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3945 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3946 bar1: /usr/X11R6/lib/libbar.so.1.0
3947 $ dpkg -s bar1 | grep Version
3950 This tells us that the <prgn>bar1</prgn> package, version
3951 1.0-1 is the one we are using. Now we can create our own
3952 <tt>debian/shlibs.local</tt> to temporarily fix the above
3953 problem. Include the following line into your
3954 <tt>debian/shlibs.local</tt> file.
3956 libbar 1 bar1 (>= 1.0-1)
3958 Now your package build should work. As soon as the
3959 maintainer of <prgn>libbar1</prgn> provides a
3960 <tt>shlibs</tt> file, you can remove your
3961 <tt>debian/shlibs.local</tt> file.
3967 <chapt><heading>The Operating System</heading>
3971 <heading>File system hierarchy</heading>
3975 <heading>Linux File system Structure</heading>
3978 The location of all installed files and directories must
3979 comply with the Linux File system Hierarchy Standard
3980 (FHS). The latest version of this document can be found
3981 alongside this manual or on
3982 <url id="http://www.pathname.com/fhs/">.
3983 Specific questions about following the standard may be
3984 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3985 Quinlan, the FHS coordinator, at
3986 <email>quinlan@pathname.com</email>.</p></sect1>
3990 <heading>Site-specific programs</heading>
3993 As mandated by the FHS, packages must not place any
3994 files in <tt>/usr/local</tt>, either by putting them in
3995 the file system archive to be unpacked by <prgn>dpkg</prgn>
3996 or by manipulating them in their maintainer scripts.</p>
3999 However, the package may create empty directories below
4000 <tt>/usr/local</tt> so that the system administrator knows
4001 where to place site-specific files. These directories
4002 should be removed on package removal if they are
4006 Note, that this applies only to directories <em>below</em>
4007 <tt>/usr/local</tt>, not <em>in</em>
4008 <tt>/usr/local</tt>. Packages must not create sub-directories
4009 in the directory <tt>/usr/local</tt> itself, except those listed in
4010 FHS, section 4.5. However, you may create directories
4011 below them as you wish. You must not remove any of the
4012 directories listed in 4.5, even if you created them.</p>
4015 Since <tt>/usr/local</tt> can be mounted read-only from a
4016 remote server, these directories must be created and
4017 removed by the <tt>postinst</tt> and <tt>prerm</tt>
4018 maintainer scripts. These scripts must not fail if either
4019 of these operations fail. (In the future, it will be
4020 possible to tell <prgn>dpkg</prgn> not to unpack files
4021 matching certain patterns, so that the directories can be
4022 included in the <tt>.deb</tt> packages and system
4023 administrators who do not wish these directories in
4024 /usr/local do not need to have them.)</p>
4027 For example, the <prgn>emacs</prgn> package will contain
4029 mkdir -p /usr/local/lib/emacs/site-lisp || true
4031 in the <tt>postinst</tt> script, and
4033 rmdir /usr/local/lib/emacs/site-lisp || true
4034 rmdir /usr/local/lib/emacs || true
4036 in the <tt>prerm</tt> script.</p>
4039 If you do create a directory in <tt>/usr/local</tt> for
4040 local additions to a package, you should ensure that
4041 settings in <tt>/usr/local</tt> take precedence over the
4042 equivalents in <tt>/usr</tt>.</p>
4045 However, because '/usr/local' and its contents are for
4046 exclusive use of the local administrator, a package must
4047 not rely on the presence or absence of files or
4048 directories in '/usr/local' for normal operation.</p>
4051 The <tt>/usr/local</tt> directory itself and all the
4052 subdirectories created by the package should (by default) have
4053 permissions 2775 (group-writable and set-group-id) and be
4054 owned by <tt>root.staff</tt>.</p>
4059 <heading>Users and groups</heading>
4062 The Debian system can be configured to use either plain or
4063 shadow passwords.</p>
4066 Some user ids (UIDs) and group ids (GIDs) are reserved
4067 globally for use by certain packages. Because some packages
4068 need to include files which are owned by these users or
4069 groups, or need the ids compiled into binaries, these ids
4070 must be used on any Debian system only for the purpose for
4071 which they are allocated. This is a serious restriction, and
4072 we should avoid getting in the way of local administration
4073 policies. In particular, many sites allocate users and/or
4074 local system groups starting at 100.</p>
4077 Apart from this we should have dynamically allocated ids,
4078 which should by default be arranged in some sensible
4079 order--but the behavior should be configurable.</p>
4082 Packages other than <tt>base-passwd</tt> must not modify
4083 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4084 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4087 The UID and GID ranges are as follows:
4092 Globally allocated by the Debian project, the
4093 same on every Debian system. These ids will appear in
4094 the <tt>passwd</tt> and <tt>group</tt> files of all
4095 Debian systems, new ids in this range being added
4096 automatically as the <tt>base-passwd</tt> package is
4100 Packages which need a single statically allocated uid
4101 or gid should use one of these; their maintainers
4102 should ask the <tt>base-passwd</tt> maintainer for
4109 Dynamically allocated system users and groups.
4110 Packages which need a user or group, but can have this
4111 user or group allocated dynamically and differently on
4112 each system, should use `<tt>adduser --system</tt>' to
4113 create the group and/or user. <prgn>adduser</prgn>
4114 will check for the existence of the user or group, and
4115 if necessary choose an unused id based on the ranges
4116 specified in <tt>adduser.conf</tt>.</p></item>
4119 <tag>1000-29999:</tag>
4122 Dynamically allocated user accounts. By default
4123 <prgn>adduser</prgn> will choose UIDs and GIDs for
4124 user accounts in this range, though
4125 <tt>adduser.conf</tt> may be used to modify this
4129 <tag>30000-59999:</tag>
4131 <p>Reserved.</p></item>
4134 <tag>60000-64999:</tag>
4137 Globally allocated by the Debian project, but only
4138 created on demand. The ids are allocated centrally and
4139 statically, but the actual accounts are only created
4140 on users' systems on demand.</p>
4143 These ids are for packages which are obscure or which
4144 require many statically-allocated ids. These packages
4145 should check for and create the accounts in
4146 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4147 <prgn>adduser</prgn> if it has this facility) if
4148 necessary. Packages which are likely to require
4149 further allocations should have a `hole' left after
4150 them in the allocation, to give them room to
4154 <tag>65000-65533:</tag>
4156 <p>Reserved.</p></item>
4161 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4162 to the group `<tt>nogroup</tt>.'</p></item>
4168 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4169 because it is the error return sentinel value.</p>
4174 <sect id="sysvinit">
4175 <heading>System run levels</heading>
4178 <sect1 id="/etc/init.d">
4179 <heading>Introduction</heading>
4182 The <tt>/etc/init.d</tt> directory contains the scripts
4183 executed by <prgn>init</prgn> at boot time and when init
4184 state (or `runlevel') is changed (see <manref name="init"
4188 There are at least two different, yet functionally
4189 equivalent, ways of handling these scripts. For the sake
4190 of simplicity, this document describes only the symbolic
4191 link method. However, it must not be assumed by maintainer
4192 scripts that this method is being used, and any automated
4193 manipulation of the various runlevel behaviours by
4194 maintainer scripts must be performed using `update-rc.d'
4195 as described below and not by manually installing or
4196 removing symlinks. For information on the
4197 implementation details of the other method, implemented in
4198 the <tt>file-rc</tt> package, please refer to the
4199 documentation of that package.</p>
4202 These scripts are referenced by symbolic links in
4203 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4204 changing runlevels, <prgn>init</prgn> looks in the
4205 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4206 it should execute, where <var>n</var> is the runlevel that
4207 is being changed to, or `S' for the boot-up scripts.</p>
4210 The names of the links all have the form
4211 <tt>S<var>mm</var><var>script</var></tt> or
4212 <tt>K<var>mm</var><var>script</var></tt> where
4213 <var>mm</var> is a two-digit number and <var>script</var>
4214 is the name of the script (this should be the same as the
4215 name of the actual script in <tt>/etc/init.d</tt>.</p>
4218 When <prgn>init</prgn> changes runlevel first the targets
4219 of the links whose names starting with a <tt>K</tt> are
4220 executed, each with the single argument <tt>stop</tt>,
4221 followed by the scripts prefixed with an <tt>S</tt>, each
4222 with the single argument <tt>start</tt>. The <tt>K</tt>
4223 links are responsible for killing services and the
4224 <tt>S</tt> link for starting services upon entering the
4228 For example, if we are changing from runlevel 2 to
4229 runlevel 3, init will first execute all of the <tt>K</tt>
4230 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4231 all of the <tt>S</tt> prefixed scripts. The links
4232 starting with <tt>K</tt> will cause the referred-to file
4233 to be executed with an argument of <tt>stop</tt>, and the
4234 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4237 The two-digit number <var>mm</var> is used to decide which
4238 order to start and stop things in--low-numbered links have
4239 their scripts run first. For example, the <tt>K20</tt>
4240 scripts will be executed before the <tt>K30</tt> scripts.
4241 This is used when a certain service must be started before
4242 another. For example, the name server <prgn>bind</prgn>
4243 might need to be started before the news server
4244 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4245 access lists. In this case, the script that starts
4246 <prgn>bind</prgn> would have a lower number than the
4247 script that starts <prgn>inn</prgn> so that it runs first:
4256 <heading>Writing the scripts</heading>
4259 Packages that include daemons for system services should
4260 place scripts in <tt>/etc/init.d</tt> to start or stop
4261 services at boot time or during a change of runlevel.
4262 These scripts should be named
4263 <tt>/etc/init.d/<var>package</var></tt>, and they should
4264 accept one argument, saying what to do:
4267 <tag><tt>start</tt></tag>
4268 <item><p>start the service,</p></item>
4270 <tag><tt>stop</tt></tag>
4271 <item><p>stop the service,</p></item>
4273 <tag><tt>restart</tt></tag>
4274 <item><p>stop and restart the service,</p></item>
4276 <tag><tt>reload</tt></tag>
4277 <item><p>cause the configuration of the service to be
4278 reloaded without actually stopping and restarting
4279 the service,</p></item>
4281 <tag><tt>force-reload</tt></tag> <item><p>cause the
4282 configuration to be reloaded if the service supports
4283 this, otherwise restart the service.</p></item>
4286 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4287 <tt>force-reload</tt> options should be supported by all
4288 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4289 option is optional.</p>
4292 The <tt>init.d</tt> scripts should ensure that they will
4293 behave sensibly if invoked with <tt>start</tt> when the
4294 service is already running, or with <tt>stop</tt> when it
4295 isn't, and that they don't kill unfortunately-named user
4296 processes. The best way to achieve this is usually to use
4297 <prgn>start-stop-daemon</prgn>.</p>
4300 If a service reloads its configuration automatically (as
4301 in the case of <prgn>cron</prgn>, for example), the
4302 <tt>reload</tt> option of the <tt>init.d</tt> script
4303 should behave as if the configuration has been reloaded
4307 These scripts should not fail obscurely when the
4308 configuration files remain but the package has been
4309 removed, as configuration files remain on the system after
4310 the package has been removed. Only when <prgn>dpkg</prgn>
4311 is executed with the <tt>--purge</tt> option will
4312 configuration files be removed. In particular, the init
4313 script itself is usually a configuration file (see
4314 <ref id="init.d notes">), and will remain on the system if
4315 the package is removed but not purged. Therefore, you
4316 should include a <tt>test</tt> statement at the top of the
4319 test -f <var>program-executed-later-in-script</var> || exit 0
4323 Often there are some values in the `<tt>init.d</tt>'
4324 scripts that a system administrator will frequently want
4325 to change. While the scripts are frequently conffiles,
4326 modifying them requires that the administrator merge in
4327 their changes each time the package is upgraded and the
4328 conffile changes. To ease the burden on the system
4329 administrator, such configurable values should not be
4330 placed directly in the script. Instead, they should be
4331 placed in a file in `<tt>/etc/default</tt>', which
4332 typically will have the same base name as the
4333 `<tt>init.d</tt>' script. This extra file can be sourced
4334 by the script when the script runs. It must contain only
4335 variable settings and comments.
4339 To ensure that vital configurable values are always
4340 available, the `<tt>init.d</tt>' script should set default
4341 values for each of the shell variables it uses before
4342 sourcing the <tt>/etc/default/</tt> file. Also, since the
4343 `<tt>/etc/default/</tt>' file is often a conffile, the
4344 `<tt>init.d</tt>' script must behave sensibly without
4345 failing if it is deleted.
4351 <heading>Managing the links</heading>
4354 The program <prgn>update-rc.d</prgn> is provided to make
4355 it easier for package maintainers to arrange for the
4356 proper creation and removal of
4357 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4358 functional equivalent if another method is being used.
4359 This may be used by maintainers in their packages'
4360 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4363 You must use this script to make changes to
4364 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4365 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4366 in the actual archive or manually create or remove the
4367 symbolic links in maintainer scripts. (The latter will
4368 fail if an alternative method of maintaining runlevel
4369 information is being used.)</p>
4372 By default <prgn>update-rc.d</prgn> will start services in
4373 each of the multi-user state runlevels (2, 3, 4, and 5)
4374 and stop them in the halt runlevel (0), the single-user
4375 runlevel (1) and the reboot runlevel (6). The system
4376 administrator will have the opportunity to customize
4377 runlevels by either running <prgn>update-rc.d</prgn>, by
4378 simply adding, moving, or removing the symbolic links in
4379 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4380 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4381 <tt>file-rc</tt> method is being used.</p>
4384 To get the default behavior for your package, put in your
4385 <tt>postinst</tt> script
4387 update-rc.d <var>package</var> defaults >/dev/null
4389 and in your <tt>postrm</tt>
4391 if [ purge = "$1" ]; then
4392 update-rc.d <var>package</var> remove >/dev/null
4397 This will use a default sequence number of 20. If it does
4398 not matter when or in which order the script is run, use
4399 this default. If it does, then you should talk to the
4400 maintainer of the <prgn>sysvinit</prgn> package or post to
4401 <tt>debian-devel</tt>, and they will help you choose a
4405 For more information about using <tt>update-rc.d</tt>,
4406 please consult its manpage <manref name="update-rc.d"
4407 section="8">.</p></sect1>
4411 <heading>Boot-time initialization</heading>
4414 There used to be another directory, <tt>/etc/rc.boot</tt>,
4415 which contained scripts which were run once per machine
4416 boot. This has been deprecated in favour of links from
4417 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4418 described in <ref id="/etc/init.d">. Packages must not
4419 place files in <tt>/etc/rc.boot</tt>.</p>
4421 <sect1 id="init.d notes">
4422 <heading>Notes</heading>
4425 <em>Do not</em> include the
4426 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4427 <tt>.deb</tt> file system archive! <em>This will cause
4428 problems!</em> You must create them with
4429 <prgn>update-rc.d</prgn>, as above.</p>
4432 <em>Do not</em> include the
4433 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4434 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4435 problems!</em> You should, however, treat the
4436 <tt>/etc/init.d</tt> scripts as configuration files,
4437 either by marking them as conffiles or managing them
4438 correctly in the maintainer scripts (see
4439 <ref id="config files">). (This is important since we want
4440 to give the local system administrator the chance to adapt
4441 the scripts to the local system--e.g., to disable a
4442 service without de-installing the package, or to specify
4443 some special command line options when starting a
4444 service--while making sure her changes aren't lost during
4445 the next package upgrade.)</p>
4449 <heading>Example</heading>
4452 The <prgn>bind</prgn> DNS (nameserver) package wants to
4453 make sure that the nameserver is running in multiuser
4454 runlevels, and is properly shut down with the system. It
4455 puts a script in <tt>/etc/init.d</tt>, naming the script
4456 appropriately <tt>bind</tt>. As you can see, the script
4457 interprets the argument <tt>reload</tt> to send the
4458 nameserver a <tt>HUP</tt> signal (causing it to reload its
4459 configuration); this way the user can say
4460 <tt>/etc/init.d/bind reload</tt> to reload the name
4461 server. The script has one configurable value, which can
4462 be used to pass parameters to the named program at
4470 # Original version by Robert Leslie
4471 # <rob@mars.org>, edited by iwj and cs
4473 test -x /usr/sbin/named || exit 0
4475 # Source defaults file.
4477 if [ -f /etc/default/bind ]; then
4484 echo -n "Starting domain name service: named"
4485 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4490 echo -n "Stopping domain name service: named"
4491 start-stop-daemon --stop --quiet \
4492 --pidfile /var/run/named.pid --exec /usr/sbin/named
4496 echo -n "Restarting domain name service: named"
4497 start-stop-daemon --stop --quiet \
4498 --pidfile /var/run/named.pid --exec /usr/sbin/named
4499 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4503 force-reload|reload)
4504 echo -n "Reloading configuration of domain name service: named"
4505 start-stop-daemon --stop --signal 1 --quiet \
4506 --pidfile /var/run/named.pid --exec /usr/sbin/named
4510 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4520 Complementing the above init script is a file
4521 '<tt>/etc/default/bind</tt>', which contains configurable
4522 parameters used by the script.
4526 # Specified parameters to pass to named. See named(8).
4527 # You may uncomment the following line, and edit to taste.
4533 Another example on which to base your <tt>/etc/init.d</tt>
4534 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4537 If this package is happy with the default setup from
4538 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4539 and having named running in all runlevels, it can say in
4540 its <tt>postinst</tt>:
4542 update-rc.d bind defaults >/dev/null
4544 And in its <tt>postrm</tt>, to remove the links when the
4547 if [ purge = "$1" ]; then
4548 update-rc.d bind remove >/dev/null
4554 <heading>Cron jobs</heading>
4557 Packages must not modify the configuration file
4558 <tt>/etc/crontab</tt>, and they must not modify the files in
4559 <tt>/var/spool/cron/crontabs</tt>.</p>
4562 If a package wants to install a job that has to be executed
4563 via cron, it should place a file with the name of the
4564 package in one of the following directories:
4570 As these directory names imply, the files within them are
4571 executed on a daily, weekly, or monthly basis,
4572 respectively. The exact times are listed in
4573 <tt>/etc/crontab</tt>.</p>
4576 All files installed in any of these directories must be
4577 scripts (shell scripts, Perl scripts, etc.) so that they can
4578 easily be modified by the local system administrator. In
4579 addition, they should be treated as configuration files.</p>
4582 If a certain job has to be executed more frequently than
4583 daily, the package should install a file
4584 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4585 the same syntax as <tt>/etc/crontab</tt> and is processed by
4586 <prgn>cron</prgn> automatically. The file must also be
4587 treated as a configuration file. (Note, that entries in the
4588 <tt>/etc/cron.d</tt> directory are not handled by
4589 <prgn>anacron</prgn>. Thus, you should only use this
4590 directory for jobs which may be skipped if the system is not
4594 The scripts or crontab entries in these directories should
4595 check if all necessary programs are installed before they
4596 try to execute them. Otherwise, problems will arise when a
4597 package was removed but not purged since configuration files
4598 are kept on the system in this situation.</p>
4602 <heading>Console messages</heading>
4605 This section describes different formats for messages
4606 written to standard output by the <tt>/etc/init.d</tt>
4607 scripts. The intent is to improve the consistency of
4608 Debian's startup and shutdown look and feel.</p>
4611 Please look very careful at the details. We want to get the
4612 messages to look exactly the same way concerning spaces,
4613 punctuation, and case of letters.</p>
4616 Here is a list of overall rules that you should use when you
4617 create output messages. They can be useful if you have a
4618 non-standard message that isn't covered in the sections
4625 Every message should cover one line, start with a
4626 capital letter and end with a period `.'.</p></item>
4631 If you want to express that the computer is working on
4632 something (performing a specific task, not starting or
4633 stopping a program), we use an ``ellipsis'', namely
4634 three dots `...'. Note that we don't insert spaces in
4635 front of or behind the dots. If the task has been
4636 completed we write `done.' and a line feed.</p></item>
4641 Design your messages as if the computer is telling you
4642 what he is doing (let him be polite :-) but don't
4643 mention ``him'' directly. For example, if you think
4646 I'm starting network daemons: nfsd mountd.
4650 Starting network daemons: nfsd mountd.
4651 </example></p></item>
4655 The following formats should be used</p>
4660 <p>when daemons get started.</p>
4663 Use this format if your script starts one or more
4664 daemons. The output should look like this (a single
4665 line, no leading spaces):
4667 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4669 The <description> should describe the subsystem
4670 the daemon or set of daemons are part of, while
4671 <daemon-1> up to <daemon-n> denote each
4672 daemon's name (typically the file name of the
4676 For example, the output of /etc/init.d/lpd would look like:
4678 Starting printer spooler: lpd.
4682 This can be achieved by saying
4684 echo -n "Starting printer spooler: lpd"
4685 start-stop-daemon --start --quiet lpd
4688 in the script. If you have more than one daemon to
4689 start, you should do the following:
4691 echo -n "Starting remote file system services:"
4692 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4693 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4694 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4697 This makes it possible for the user to see what takes
4698 so long and when the final daemon has been
4699 started. You should be careful where to put spaces: In the
4700 example above the system administrator can easily
4701 comment out a line if he don't wants to start a
4702 specific daemon, while the displayed message still
4703 looks good.</p></item>
4707 <p>when something needs to be configured.</p>
4710 If you have to set up different parameters of the
4711 system upon boot up, you should use this format:
4713 Setting <parameter> to `<value>'.
4717 You can use the following echo statement to get the quotes right:
4719 echo "Setting DNS domainname to \`"value"'."
4723 Note that the left quotation mark (`) is different
4724 from the right (').</p></item>
4727 <p>when a daemon is stopped.</p>
4730 When you stop a daemon you should issue a message
4731 similar to the startup message, except that `Starting'
4732 is replaced with `Stopping'.</p>
4735 So stopping the printer daemon will like like this:
4737 Stopping printer spooler: lpd.
4738 </example></p></item>
4741 <p>when something is executed.</p>
4744 There are several examples where you have to run a
4745 program at system startup or shutdown to perform a
4746 specific task. For example, setting the system's clock
4747 via `netdate' or killing all processes when the system
4748 comes down. Your message should like this:
4750 Doing something very useful...done.
4752 You should print the `done.' right after the job has been completed,
4753 so that the user gets informed why he has to wait. You can get this
4756 echo -n "Doing something very useful..."
4760 in your script.</p></item>
4763 <p>when the configuration is reloaded.</p>
4766 When a daemon is forced to reload its configuration
4767 files you should use the following format:
4769 Reloading <daemon's-name> configuration...done.
4770 </example></p></item>
4773 <p>when none of the above rules apply.</p>
4776 If you have to print a message that doesn't fit into
4777 the styles described above, you can use something
4778 appropriate, but please have a look at the overall
4779 rules listed above.</p></item>
4784 <heading>Menus</heading>
4787 Menu entries should follow the current menu policy as
4788 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4789 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4790 or your local mirror. In addition, it is included in the
4791 <tt>debian-policy</tt> package.
4795 The Debian <tt>menu</tt> packages provides a unique
4796 interface between packages providing applications and
4797 documents, and <em>menu programs</em> (either X window
4798 managers or text-based menu programs as
4799 <prgn>pdmenu</prgn>).</p>
4802 All packages that provide applications that need not be
4803 passed any special command line arguments for normal
4804 operation should register a menu entry for those
4805 applications, so that users of the <tt>menu</tt> package
4806 will automatically get menu entries in their window
4807 managers, as well in shells like <tt>pdmenu</tt>.</p>
4810 Please refer to the <em>Debian Menu System</em> document
4811 that comes with the <tt>menu</tt> package for information
4812 about how to register your applications and web
4818 <heading>Multimedia handlers</heading>
4821 Packages which provide the ability to view/show/play,
4822 compose, edit or print MIME types should register themselves
4823 as such following the current MIME support policy as defined
4824 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4825 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4826 or your local mirror. In addition, it is included in the
4827 <tt>debian-policy</tt> package.
4831 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4832 mechanism for encoding files and data streams and providing
4833 meta-information about them, in particular their type (e.g.
4834 audio or video) and format (e.g. PNG, HTML, MP3).
4838 Registration of MIME type handlers allows programs like mail
4839 user agents and web browsers to to invoke these handlers to
4840 view, edit or display MIME types they don't support
4846 <heading>Keyboard configuration</heading>
4849 To achieve a consistent keyboard configuration (i.e., all
4850 applications interpret a keyboard event the same way) all
4851 programs in the Debian distribution must be configured to
4852 comply with the following guidelines.</p>
4855 Here is a list that contains certain keys and their interpretation:
4858 <tag><tt><--</tt></tag>
4859 <item><p>delete the character to the left of the cursor</p></item>
4861 <tag><tt>Delete</tt></tag>
4862 <item><p>delete the character to the right of the cursor</p></item>
4864 <tag><tt>Control+H</tt></tag>
4865 <item><p>emacs: the help prefix</p></item>
4868 The interpretation of any keyboard events should be independent
4869 of the terminal that's used, be it a virtual console, an X
4870 terminal emulator, an rlogin/telnet session, etc.</p>
4873 The following list explains how the different programs
4874 should be set up to achieve this:</p>
4877 <list compact="compact">
4878 <item><p>`<tt><--</tt>' generates KB_Backspace in
4881 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4885 X translations are set up to make KB_Backspace
4886 generate ASCII DEL, and to make KB_Delete generate
4887 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4888 the `delete character' key). This must be done by
4889 loading the resources using xrdb on all local X
4890 displays, not using the application defaults, so that
4891 the translation resources used correspond to the
4892 xmodmap settings.</p></item>
4896 The Linux console is configured to make
4897 `<tt><--</tt>' generate DEL, and `Delete' generate
4898 <tt>ESC [ 3 ~</tt> (this is the case at the
4902 X applications are configured so that Backspace
4903 deletes left, and Delete deletes right. Motif
4904 applications already work like this.</p></item>
4906 <item><p>stty erase <tt>^?</tt> .</p></item>
4909 The `xterm' terminfo entry should have <tt>ESC [ 3
4910 ~</tt> for kdch1, just like TERM=linux and
4911 TERM=vt220.</p></item>
4914 Emacs is programmed to map KB_Backspace or the `stty
4915 erase' character to delete-backward-char, and
4916 KB_Delete or kdch1 to delete-forward-char, and
4917 <tt>^H</tt> to help as always.</p></item>
4920 Other applications use the `stty erase' character and
4921 kdch1 for the two delete keys, with ASCII DEL being
4922 `delete previous character' and kdch1 being `delete
4923 character under cursor'.</p></item>
4927 This will solve the problem except for:</p>
4930 <list compact="compact">
4932 Some terminals have a <tt><--</tt> key that cannot
4933 be made to produce anything except <tt>^H</tt>. On
4934 these terminals Emacs help will be unavailable on
4935 <tt>^H</tt> (assuming that the `stty erase' character
4936 takes precedence in Emacs, and has been set
4937 correctly). M-x help or F1 (if available) can be used
4941 Some operating systems use <tt>^H</tt> for stty erase.
4942 However, modern telnet versions and all rlogin
4943 versions propagate stty settings, and almost all UNIX
4944 versions honour stty erase. Where the stty settings
4945 are not propagated correctly things can be made to
4946 work by using stty manually.</p></item>
4949 Some systems (including previous Debian versions) use
4950 xmodmap to arrange for both <tt><--</tt> and Delete
4951 to generate KB_Delete. We can change the behavior
4952 of their X clients via the same X resources that we
4953 use to do it for our own, or have our clients be
4954 configured via their resources when things are the
4955 other way around. On displays configured like this
4956 Delete will not work, but <tt><--</tt>
4960 Some operating systems have different kdch1 settings
4961 in their terminfo for xterm and others. On these
4962 systems the Delete key will not work correctly when
4963 you log in from a system conforming to our policy, but
4964 <tt><--</tt> will.</p></item>
4971 <heading>Environment variables</heading>
4974 A program must not depend on environment variables to get
4975 reasonable defaults. (That's because these environment
4976 variables would have to be set in a system-wide
4977 configuration file like /etc/profile, which is not supported
4981 If a program usually depends on environment variables for its
4982 configuration, the program should be changed to fall back to
4983 a reasonable default configuration if these environment
4984 variables are not present. If this cannot be done easily
4985 (e.g., if the source code of a non-free program is not
4986 available), the program must be replaced by a small
4987 `wrapper' shell script which sets the environment variables
4988 if they are not already defined, and calls the original program.</p>
4991 Here is an example of a wrapper script for this purpose:
4995 BAR=${BAR:-/var/lib/fubar}
4997 exec /usr/lib/foo/foo "$@"
5001 Furthermore, as <tt>/etc/profile</tt> is a configuration
5002 file of the <prgn>base-files</prgn> package, other packages must not
5003 put any environment variables or other commands into that
5008 <heading>Files</heading>
5012 <heading>Binaries</heading>
5015 Two different packages must not install programs with
5016 different functionality but with the same filenames. (The
5017 case of two programs having the same functionality but
5018 different implementations is handled via `alternatives.')
5019 If this case happens, one of the programs must be
5020 renamed. The maintainers should report this to the
5021 developers' mailing and try to find a consensus about
5022 which package will have to be renamed. If a consensus can
5023 not be reached, <em>both</em> programs must be
5027 Generally the following compilation parameters should be used:
5030 CFLAGS = -O2 -Wall # sane warning options vary between programs
5032 install -s # (or use strip on the files in debian/tmp)
5036 Note that by default all installed binaries should be stripped,
5037 either by using the <tt>-s</tt> flag to
5038 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5039 the binaries after they have been copied into
5040 <tt>debian/tmp</tt> but before the tree is made into a
5044 The <tt>-N</tt> flag should not be used. On a.out systems
5045 it may have been useful for some very small binaries, but
5046 for ELF it has no good effect.</p>
5049 Debugging symbols are useful for error diagnosis,
5050 investigation of core dumps (which may be submitted by users
5051 in bug reports), or testing and developing the
5052 software. Therefore it is recommended to support building
5053 the package with debugging information through the following
5054 interface: If the environment variable
5055 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5056 <tt>debug</tt>, compile the software with debugging
5057 information (usually this involves adding the <tt>-g</tt>
5058 flag to <tt>CFLAGS</tt>). This allows the generation of a
5059 build tree with debugging information. If the environment
5060 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5061 <tt>nostrip</tt>, do not strip the files at installation
5062 time. This allows one to generate a package with debugging
5063 information included. The following makefile snippet is only
5064 an example of how one may test for either condition:
5067 Rationale: Building by default with -g causes more
5068 wasted CPU cycles since the information is stripped away
5069 anyway. The package can by default build without -g if
5070 it also provides a mechanism to easily be rebuilt with
5071 debugging information. This can be done by providing a
5072 "build-debug" make target, or allowing the user to
5073 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5074 compiling that package.
5076 <p>Now this has several added benefits:
5080 It is actually easier to build debugging bins and
5081 libraries this way (no more editing debian/rules
5082 or similar) since it provides a documented way of
5083 getting this type of build.</p>
5087 There will be much less wasted CPU time for the
5088 autobuilders since not having debugging
5089 information (and hence also not having to strip
5090 it) will increase the speed of compiles. This
5091 skips an entire pass of the compiler.
5102 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5103 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5104 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5105 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5107 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5110 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5111 INSTALL_PROGRAM += -s
5115 Please note that the above example is merely informative,
5116 and is not a policy mandate. You may have to massage this
5117 example in order to make it work for your package.
5122 It is up to the package maintainer to decide what
5123 compilation options are best for the package. Certain
5124 binaries (such as computationally-intensive programs) will
5125 function better with certain flags (<tt>-O3</tt>, for
5126 example); feel free to use them. Please use good judgment
5127 here. Don't use flags for the sake of it; only use them
5128 if there is good reason to do so. Feel free to override
5129 the upstream author's ideas about which compilation
5130 options are best--they are often inappropriate for our
5131 environment.</p></sect>
5135 <heading>Libraries</heading>
5138 All libraries must have a shared version in the lib
5139 package and a static version in the lib-dev package. The
5140 shared version must be compiled with <tt>-fPIC</tt>, and
5141 the static version must not be. In other words, each
5142 <tt>*.c</tt> file will need to be compiled twice.</p>
5145 You must specify the gcc option <tt>-D_REENTRANT</tt>
5146 when building a library (either static or shared) to make
5147 the library compatible with LinuxThreads.</p>
5150 Note that all installed shared libraries should be
5153 strip --strip-unneeded <your-lib>
5155 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5156 only the symbols which aren't needed for relocation
5157 processing.) Shared libraries can function perfectly well
5158 when stripped, since the symbols for dynamic linking are
5159 in a separate part of the ELF object file.</p>
5162 Note that under some circumstances it may be useful to
5163 install a shared library unstripped, for example when
5164 building a separate package to support debugging.
5168 An ever increasing number of packages are using libtool to
5169 do their linking. The latest GNU libtools (>= 1.3a) can take
5170 advantage of the metadata in the installed libtool archive
5171 files (`*.la'). The main advantage of libtool's .la files is
5172 that it allows libtool to store and subsequently access
5173 metadata with respect to the libraries it builds. libtool
5174 will search for those files, which contain a lot of useful
5175 information about a library (e.g. dependency libraries for
5176 static linking). Also, they're <em>essential</em> for
5177 programs using libltdl.
5181 Certainly libtool is fully capable of linking against shared
5182 libraries which don't have .la files, but being a mere shell
5183 script it can add considerably to the build time of a
5184 libtool using package if that shell-script has to derive all
5185 this information from first principles for each library every
5186 time it is linked. With the advent of libtool-1.4 (and to a
5187 lesser extent libtool-1.3), the .la files will also store
5188 information about inter-library dependencies which cannot
5189 necessarily be derived after the .la file is deleted.
5193 Packages that use libtool to create shared libraries should
5194 include the <em>.la</em> files in the <em>-dev</em>
5195 packages, with the exception that if the package relies on
5196 libtool's <em>libltdl</em> library, in which case the .la
5197 files must go in the run-time library package. This is a
5198 good idea in general, and especially for static linking
5203 You must make sure that you use only released versions of
5204 shared libraries to build your packages; otherwise other
5205 users will not be able to run your binaries
5206 properly. Producing source packages that depend on
5207 unreleased compilers is also usually a bad
5214 <heading>Shared libraries</heading>
5217 Packages involving shared libraries should be split up
5218 into several binary packages.</p>
5221 For a straightforward library which has a development
5222 environment and a runtime kit including just shared
5223 libraries you need to create two packages:
5224 <tt><var>libraryname</var><var>soname</var></tt>
5225 (<var>soname</var> is the shared object name of the shared
5226 library--it's the thing that has to match exactly between
5227 building an executable and running it for the dynamic
5228 linker to be able run the program; usually the
5229 <var>soname</var> is the major number of the library) and
5230 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5233 If you prefer only to support one development version at a
5234 time you may name the development package
5235 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5236 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5237 ensure that the user only installs one development version
5238 at a time (after all, different development versions are
5239 likely to have the same header files in them, causing a
5240 filename clash if both are installed). Typically the
5241 development version should also have an exact version
5242 dependency on the runtime library, to make sure that
5243 compilation and linking happens correctly.</p>
5246 Packages which use the shared library should have a
5247 dependency on the name of the shared library package,
5248 <tt><var>libraryname</var><var>soname</var></tt>. When
5249 the <var>soname</var> changes you can have both versions
5250 of the library installed while moving from the old library
5254 If your package has some run-time support programs which
5255 use the shared library you must not put them in
5256 the shared library package. If you do that then you won't
5257 be able to install several versions of the shared library
5258 without getting filename clashes. Instead, either create
5259 a third package for the runtime binaries (this package
5260 might typically be named
5261 <tt><var>libraryname</var>-runtime</tt>--note the absence
5262 of the <var>soname</var> in the package name) or if the
5263 development package is small include them in there.</p>
5266 If you have several shared libraries built from the same
5267 source tree you may lump them all together into a single
5268 shared library package, provided that you change all their
5269 <var>soname</var>s at once (so that you don't get filename
5270 clashes if you try to install different versions of the
5271 combined shared libraries package).</p>
5274 You should follow the directions in the <em>Debian Packaging
5275 Manual</em> for putting the shared library in its package,
5276 and you must include a <tt>shlibs</tt> control area
5277 file with details of the dependencies for packages which
5278 use the library.</p>
5281 Shared libraries should not be installed
5282 executable, since <prgn>ld.so</prgn> does not require this
5283 and trying to execute a shared library results in a core
5288 <heading>Scripts</heading>
5291 All command scripts, including the package maintainer
5292 scripts inside the package and used by <prgn>dpkg</prgn>,
5293 should have a <tt>#!</tt> line naming the shell to be used
5294 to interpret them.</p>
5297 In the case of Perl scripts this should be
5298 <tt>#!/usr/bin/perl</tt>.</p>
5301 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5302 should almost certainly start with <tt>set -e</tt> so that
5303 errors are detected. Every script should use
5304 <tt>set -e</tt> or check the exit status of <em>every</em>
5308 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5309 symbolic link to any POSIX compatible shell, if <tt>echo
5310 -n</tt> does not generate a newline.
5313 Debian policy specifies POSIX behavior for /bin/sh, but
5314 echo -n has widespread use in the Linux community
5315 (including especially debian policy, the linux kernel
5316 source, many debian scripts, etc.). This echo -n
5317 mechanism is valid but not required under POSIX, hence
5318 this explicit addition. Also, rumour has it that this
5319 shall be mandated under the LSB anyway.
5323 specifying `<tt>/bin/sh</tt>' as interpreter should only
5324 use POSIX features. If a script requires non-POSIX
5325 features from the shell interpreter, the appropriate shell
5326 must be specified in the first line of the script (e.g.,
5327 `<tt>#!/bin/bash</tt>') and the package must depend on the
5328 package providing the shell (unless the shell package is
5329 marked `Essential', e.g., in the case of
5334 You may wish to restrict your script to POSIX features when possible so
5335 that it may use <tt>/bin/sh</tt> as its interpreter. If
5336 your script works with <prgn>ash</prgn>, it's probably
5337 POSIX compliant, but if you are in doubt, use
5338 <tt>/bin/bash</tt>.</p>
5341 Perl scripts should check for errors when making any
5342 system calls, including <tt>open</tt>, <tt>print</tt>,
5343 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5346 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5347 as scripting languages. See <em>Csh Programming
5348 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5349 FAQs. It can be found on
5350 <url id="http://language.perl.com/versus/csh.whynot">, or
5351 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5352 or even on <ftpsite>ftp.cpan.org</ftpsite>
5353 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5354 If an upstream package comes with <prgn>csh</prgn> scripts
5355 then you must make sure that they start with
5356 <tt>#!/bin/csh</tt> and make your package depend on the
5357 <prgn>c-shell</prgn> virtual package.</p>
5360 Any scripts which create files in world-writeable
5361 directories (e.g., in <tt>/tmp</tt>) must use a
5362 mechanism which will fail if a file with the same name
5366 The Debian base distribution provides the
5367 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5368 for use by scripts for this purpose.</p></sect>
5372 <heading>Symbolic links</heading>
5375 In general, symbolic links within a top-level directory
5376 should be relative, and symbolic links pointing from one
5377 top-level directory into another should be absolute. (A
5378 top-level directory is a sub-directory of the root
5382 In addition, symbolic links should be specified as short
5383 as possible, i.e., link targets like `foo/../bar' are
5387 Note that when creating a relative link using
5388 <prgn>ln</prgn> it is not necessary for the target of the
5389 link to exist relative to the working directory you're
5390 running <prgn>ln</prgn> from; nor is it necessary to
5391 change directory to the directory where the link is to be
5392 made. Simply include the string that should appear as the
5393 target of the link (this will be a pathname relative to
5394 the directory in which the link resides) as the first
5395 argument to <prgn>ln</prgn>.</p>
5398 For example, in your <prgn>Makefile</prgn> or
5399 <tt>debian/rules</tt>, do things like:
5401 ln -fs gcc $(prefix)/bin/cc
5402 ln -fs gcc debian/tmp/usr/bin/cc
5403 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5404 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5408 A symbolic link pointing to a compressed file should
5409 always have the same file extension as the referenced
5410 file. (For example, if a file `<tt>foo.gz</tt>' is
5411 referenced by a symbolic link, the filename of the link
5412 has to end with `<tt>.gz</tt>' too, as in
5413 `bar.gz.')</p></sect>
5417 <heading>Device files</heading>
5420 Packages must not include device files in the package file
5424 If a package needs any special device files that are not
5425 included in the base system, it must call
5426 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5427 after asking the user for permission to do so.</p>
5430 Packages must not remove any device files in the
5431 <tt>postrm</tt> or any other script. This is left to the
5432 system administrator.</p>
5435 Debian uses the serial devices
5436 <tt>/dev/ttyS*</tt>. Programs using the old
5437 <tt>/dev/cu*</tt> devices should be changed to use
5438 <tt>/dev/ttyS*</tt>.</p>
5441 <sect id="config files">
5442 <heading>Configuration files</heading>
5444 <heading>Definitions</heading>
5447 <tag>configuration file</tag>
5449 A file that affects the operation of program, or
5450 provides site- or host-specific information, or
5451 otherwise customizes the behavior of program.
5452 Typically, configuration files are intended to be
5453 modified by the system administrator (if needed or
5454 desired) to conform to local policy or provide more
5455 useful site-specific behavior.</p>
5458 <tag><tt>conffile</tt></tag>
5460 A file listed in a package's <tt>conffiles</tt>
5461 file, and is treated specially by <prgn>dpkg</prgn>
5462 (see the <em>Debian Packaging Manual</em>).</p>
5468 The distinction between these two is important; they are
5469 not interchangeable concepts. Almost all
5470 <tt>conffiles</tt> are configuration files, but many
5471 configuration files are not <tt>conffiles</tt>.</p>
5474 Note that a script that embeds configuration information
5475 (such as most of the files in <tt>/etc/init.d</tt> and
5476 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5477 configuration file and should be treated as such.</p>
5481 <heading>Location</heading>
5483 Any configuration files created or used by your package
5484 must reside in <tt>/etc</tt>. If there are several you
5485 should consider creating a subdirectory of <tt>/etc</tt>
5486 named after your package.</p>
5489 If your package creates or uses configuration files
5490 outside of <tt>/etc</tt>, and it is not feasible to modify
5491 the package to use the <tt>/etc</tt>, you should still put
5492 the files in <tt>/etc</tt> and create symbolic links to
5493 those files from the location that the package
5498 <heading>Behavior</heading>
5500 Configuration file handling must conform to the following
5504 <p>local changes must be preserved during a package
5508 <p>configuration files must be preserved when the
5509 package is removed, and only deleted when the
5510 package is purged.</p>
5515 The easy way to achieve this behavior is to make the
5516 configuration file a <tt>conffile</tt>. This is
5517 appropriate only if it is possible to distribute a default
5518 version that will work for most installations, although
5519 some system administrators may choose to modify it. This
5520 implies that the default version will be part of the
5521 package distribution, and must not be modified by the
5522 maintainer scripts during installation (or at any other
5527 In order to ensure that local changes are preserved
5528 correctly, no package may contain or make hard links to
5532 Rationale: There are two problems with hard links.
5533 The first is that some editors break the link while
5534 editing one of the files, so that the two files may
5535 unwittingly become different. The second is that
5536 <prgn>dpkg</prgn> might break the hard link while
5537 upgrading <tt>conffile</tt>s.
5543 The other way to do it is via the maintainer scripts.
5544 In this case, the configuration file must not be listed as
5545 a <tt>conffile</tt> and must not be part of the package
5546 distribution. If the existence of a file is required for
5547 the package to be sensibly configured it is the
5548 responsibility of the package maintainer to write scripts
5549 which correctly create, update, maintain and
5550 remove-on-purge the file. These scripts must be idempotent
5551 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5552 re-run them due to errors during installation or removal),
5553 must cope with all the variety of ways <prgn>dpkg</prgn>
5554 can call maintainer scripts, must not overwrite or
5555 otherwise mangle the user's configuration without asking,
5556 must not ask unnecessary questions (particularly during
5557 upgrades), and otherwise be good citizens.</p>
5560 The scripts are not required to configure every possible option for
5561 the package, but only those necessary to get the package
5562 running on a given system. Ideally the sysadmin should not
5563 have to do any configuration other than that done
5564 (semi-)automatically by the <tt>postinst</tt> script.</p>
5567 A common practice is to create a script called
5568 <tt><var>package</var>-configure</tt> and have the
5569 package's <tt>postinst</tt> call it if and only if the
5570 configuration file does not already exist. In certain
5571 cases it is useful for there to be an example or template
5572 file which the maintainer scripts use. Such files should
5573 be in <tt>/usr/share/<package></tt> or
5574 <tt>/usr/lib/<package></tt> with a symbolic link
5575 from <tt>/usr/share/doc/<package>/examples</tt>
5576 if they are examples, and should be
5577 perfectly ordinary <prgn>dpkg</prgn>-handled files
5578 (<em>not</em> <tt>conffiles</tt>).
5582 These two styles of configuration file handling must
5583 not be mixed, for that way lies madness:
5584 <prgn>dpkg</prgn> will ask about overwriting the file
5585 every time the package is upgraded.</p>
5590 <heading>Sharing configuration files</heading>
5592 Packages which specify the same file as
5593 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5598 The maintainer scripts must not alter the conffile of
5599 <em>any</em> package, including the one the scripts belong
5603 If two or more packages use the same configuration file
5604 and it is reasonable for both to be installed at the same
5605 time, one of these packages must be defined as
5606 <em>owner</em> of the configuration file, i.e., it will be
5607 the package to list that distributes the file and lists it
5608 as a <tt>conffile</tt>. Other packages that use the
5609 configuration file must depend on the owning package if
5610 they require the configuration file to operate. If the
5611 other package will use the configuration file if present,
5612 but is capable of operating without it, no dependency need
5616 If it is desirable for two or more related packages to
5617 share a configuration file <em>and</em> for all of the
5618 related packages to be able to modify that configuration
5619 file, then the following should be done:
5623 have one of the related packages (the "core"
5624 package) manage the configuration file with
5625 maintainer scripts as described in the previous
5629 the core package should also provide a program that
5630 the other packages may use to modify the
5631 configuration file.</p>
5635 the related packages must use the provided program
5636 to make any modifications to the configuration file.
5637 They should either depend on the core package to
5638 guarantee that the configuration modifier program is
5639 available or accept gracefully that they cannot
5640 modify the configuration file if it is not.</p>
5645 Sometimes it's appropriate to create a new package which
5646 provides the basic infrastructure for the other packages
5647 and which manages the shared configuration files. (Check
5648 out the <tt>sgml-base</tt> package as an example.)</p>
5652 <heading>User configuration files ("dotfiles")</heading>
5655 Files in <tt>/etc/skel</tt> will automatically be copied
5656 into new user accounts by <prgn>adduser</prgn>. They
5657 should not be referenced there by any program.</p>
5660 Therefore, if a program needs a dotfile to exist in
5661 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5662 should be installed in <tt>/etc/skel</tt> (and listed in
5663 conffiles, if it is not generated and modified dynamically
5664 by the package's installation scripts).</p>
5667 However, programs that require dotfiles in order to
5668 operate sensibly (dotfiles that they do not create
5669 themselves automatically, that is) are a bad thing, and
5670 programs should be configured by the Debian default
5671 installation as close to normal as possible.</p>
5674 Therefore, if a program in a Debian package needs to be
5675 configured in some way in order to operate sensibly that
5676 configuration should be done in a site-wide global
5677 configuration file elsewhere in <tt>/etc</tt>. Only if the
5678 program doesn't support a site-wide default configuration
5679 and the package maintainer doesn't have time to add it
5680 may a default per-user file be placed in
5681 <tt>/etc/skel</tt>.</p>
5684 <tt>/etc/skel</tt> should be as empty as we can make it.
5685 This is particularly true because there is no easy
5686 mechanism for ensuring that the appropriate dotfiles are
5687 copied into the accounts of existing users when a package
5693 <heading>Log files</heading>
5695 The traditional approach to log files has been to set up ad
5696 hoc log rotation schemes using simple shell scripts and
5697 cron. While this approach is highly customizable, it
5698 requires quite a lot of sysadmin work. Even though the
5699 original Debian system helped a little by automatically
5700 installing a system which can be used as a template, this
5701 was deemed not enough.
5705 A better scheme is to use logrotate, a GPL'd program
5706 developed by Red Hat, which centralizes log management. It
5707 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5708 and a directory where packages can drop logrotation info
5709 (<tt>/etc/logrotate.d</tt>).
5713 Log files should usually be named
5714 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5715 log files, or need a separate directory for permissions
5716 reasons (<tt>/var/log</tt> is writable only by
5717 <tt>root</tt>), you should usually create a directory named
5718 <tt>/var/log/<var>package</var></tt>.</p>
5721 Log files must be rotated occasionally so
5722 that they don't grow indefinitely; the best way to do this
5723 is to drop a script into the directory
5724 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5725 logrotate. Here is a good example for a logrotate config
5726 file (for more information see <manref name="logrotate"
5734 /etc/init.d/foo force-reload
5738 Which rotates all files under `/var/log/foo', saves 12
5739 compressed generations, and sends a HUP signal at the end of
5745 Log files should be removed when the package is
5746 purged (but not when it is only removed), by checking the
5747 argument to the <tt>postrm</tt> script (see the <em>Debian
5748 Packaging Manual</em> for details).</p>
5753 <heading>Permissions and owners</heading>
5756 The rules in this section are guidelines for general use.
5757 If necessary you may deviate from the details below.
5758 However, if you do so you must make sure that what is done
5759 is secure and you should try to be as consistent as possible
5760 with the rest of the system. You should probably also
5761 discuss it on <prgn>debian-devel</prgn> first.</p>
5764 Files should be owned by <tt>root.root</tt>, and made
5765 writable only by the owner and universally readable (and
5766 executable, if appropriate).</p>
5769 Directories should be mode 755 or (for group-writability)
5770 mode 2775. The ownership of the directory should be
5771 consistent with its mode--if a directory is mode 2775, it
5772 should be owned by the group that needs write access to
5776 Setuid and setgid executables should be mode 4755 or 2755
5777 respectively, and owned by the appropriate user or group.
5778 They should not be made unreadable (modes like 4711 or
5779 2711 or even 4111); doing so achieves no extra security,
5780 because anyone can find the binary in the freely available
5781 Debian package--it is merely inconvenient. For the same
5782 reason you should not restrict read or execute permissions
5783 on non-set-id executables.</p>
5786 Some setuid programs need to be restricted to particular
5787 sets of users, using file permissions. In this case they
5788 should be owned by the uid to which they are set-id, and
5789 by the group which should be allowed to execute them.
5790 They should have mode 4754; there is no point in making
5791 them unreadable to those users who must not be allowed to
5795 You must not arrange that the system administrator can only
5796 reconfigure the package to correspond to their local
5797 security policy by changing the permissions on a binary.
5798 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5799 to conffiles and other similar objects) have their
5800 permissions reset to the distributed permissions when the
5801 package is reinstalled. Instead you should consider (for
5802 example) creating a group for people allowed to use the
5803 program(s) and making any setuid executables executable
5804 only by that group.</p>
5807 If you need to create a new user or group for your package
5808 there are two possibilities. Firstly, you may need to
5809 make some files in the binary package be owned by this
5810 user or group, or you may need to compile the user or
5811 group id (rather than just the name) into the binary
5812 (though this latter should be avoided if possible, as in
5813 this case you need a statically allocated id).</p>
5816 If you need a statically allocated id, you must ask for a
5817 user or group id from the base system
5818 maintainer, and must not release the package until you
5819 have been allocated one. Once you have been allocated one
5820 you must make the package depend on a version of the base
5821 system with the id present in <tt>/etc/passwd</tt> or
5822 <tt>/etc/group</tt>, or alternatively arrange for your
5823 package to create the user or group itself with the
5824 correct id (using <tt>adduser</tt>) in its pre- or
5825 post-installation script (the latter is to be preferred if
5826 it is possible).</p>
5829 On the other hand, the program might be able to determine the
5830 uid or gid from the group name at runtime, so that a
5831 dynamic id can be used. In this case you should choose an
5832 appropriate user or group name, discussing this on
5833 <prgn>debian-devel</prgn> and checking with the base
5834 system maintainer that it is unique and that they do not
5835 wish you to use a statically allocated id instead. When
5836 this has been checked you must arrange for your package to
5837 create the user or group if necessary using
5838 <prgn>adduser</prgn> in the pre- or post-installation
5839 script (again, the latter is to be preferred if it is
5843 Note that changing the numeric value of an id associated with a name
5844 is very difficult, and involves searching the file system for all
5845 appropriate files. You need to think carefully whether a static or
5846 dynamic id is required, since changing your mind later will cause
5852 <heading>Customized programs</heading>
5854 <sect id="arch-spec">
5855 <heading>Architecture specification strings</heading>
5858 If a program needs to specify an <em>architecture specification
5859 string</em> in some place, the following format should be used:
5861 <arch>-<os>
5863 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5864 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5865 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5866 operating system.</p>
5868 Note, that we don't want to use `<arch>-debian-linux'
5869 to apply to the rule `architecture-vendor-os' since this
5870 would make our programs incompatible to other Linux
5871 distributions. Also note, that we don't use
5872 `<arch>-unknown-linux', since the `unknown' does not
5873 look very good.</p></sect>
5877 <heading>Daemons</heading>
5880 The configuration files <tt>/etc/services</tt>,
5881 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5882 by the <prgn>netbase</prgn> package and may not be modified
5883 by other packages.</p>
5886 If a package requires a new entry in one of these files, the
5887 maintainer should get in contact with the
5888 <prgn>netbase</prgn> maintainer, who will add the entries
5889 and release a new version of the <prgn>netbase</prgn>
5893 The configuration file <tt>/etc/inetd.conf</tt> must not be
5894 modified by the package's scripts except via the
5895 <prgn>update-inetd</prgn> script or the
5896 <prgn>DebianNet.pm</prgn> Perl module.</p>
5899 If a package wants to install an example entry into
5900 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5901 exactly one hash character (<tt>#</tt>). Such lines are
5902 treated as `commented out by user' by the
5903 <prgn>update-inetd</prgn> script and are not changed or
5904 activated during a package updates.</p></sect>
5908 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5911 Some programs need to create pseudo-ttys. This should be done
5912 using Unix98 ptys if the C library supports it. The resulting
5913 program must not be installed setuid root, unless that
5914 is required for other functionality.
5918 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5919 <tt>/var/log/lastlog</tt> must be installed writeable by
5920 group utmp. Programs who need to modify those files must
5921 be installed setgid utmp.
5926 <heading>Editors and pagers</heading>
5929 Some programs have the ability to launch an editor or pager
5930 program to edit or display a text document. Since there are
5931 lots of different editors and pagers available in the Debian
5932 distribution, the system administrator and each user should
5933 have the possibility to choose his/her preferred editor and
5937 In addition, every program should choose a good default
5938 editor/pager if none is selected by the user or system
5942 Thus, every program that launches an editor or pager must
5943 use the EDITOR or PAGER environment variables to determine
5944 the editor/pager the user wants to get started. If these
5945 variables are not set, the programs <tt>/usr/bin/editor</tt>
5946 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5949 These two files are managed through `alternatives.' That is,
5950 every package providing an editor or pager must call the
5951 <prgn>update-alternatives</prgn> script to register these
5955 If it is very hard to adapt a program to make us of the
5956 EDITOR and PAGER variables, that program may be configured
5957 to use <tt>/usr/bin/sensible-editor</tt> and
5958 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5959 respectively. These are two scripts provided in the Debian
5960 base system that check the EDITOR and PAGER variables and
5961 launch the appropriate program or fall back to
5962 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5966 A program may also use the VISUAL environment variable to
5967 determine the user's choice of editor. If it exists, it
5968 should take precedence over EDITOR. This is in fact what
5969 <tt>/usr/bin/sensible-editor</tt> does.</p>
5972 It is not required for a package to depend on
5973 `editor' and `pager', nor is it required for a package to
5974 provide such virtual packages.
5977 The Debian base system already provides an editor and
5986 <sect id="web-appl">
5987 <heading>Web servers and applications</heading>
5990 This section describes the locations and URLs that should
5991 be used by all web servers and web application in the Debian
5997 <p>Cgi-bin executable files are installed in the
6000 /usr/lib/cgi-bin/<cgi-bin-name>
6002 and should be referred to as
6004 http://localhost/cgi-bin/<cgi-bin-name>
6005 </example></p></item>
6008 <item><p>Access to html documents</p>
6011 Html documents for a package are stored in
6012 <tt>/usr/share/doc/<var>package</var></tt> but should
6013 be accessed via symlinks as
6014 <tt>/usr/doc/<var>package</var></tt><footnote> for
6015 backward compatibility, see <ref id="usrdoc"></footnote>
6016 and can be referred to as
6018 http://localhost/doc/<package>/<filename>
6019 </example></p></item>
6022 <item><p>Web Document Root</p>
6025 Web Applications should try to avoid storing files in
6026 the Web Document Root. Instead they should use the
6027 /usr/share/doc/<package> directory for documents and
6028 register the Web Application via the menu package. If
6029 access to the web-root is unavoidable then use
6033 as the Document Root. This might be just a
6034 symbolic link to the location where the sysadmin has
6035 put the real document root.</p>
6038 </enumlist></p></sect>
6042 <heading>Mail transport, delivery and user agents</heading>
6045 Debian packages which process electronic mail, whether
6046 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6047 must make sure that they are compatible with the
6048 configuration decisions below. Failure to do this may
6049 result in lost mail, broken <tt>From:</tt> lines, and other
6050 serious brain damage!</p>
6053 The mail spool is <tt>/var/spool/mail</tt> and the interface
6054 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6055 per the FHS). The mail spool is part of the base system
6056 and not part of the MTA package.</p>
6059 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6060 programs (like IMAP daemons) must lock the mailbox in an
6061 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6062 be combined with dot locking. To avoid deadlocks, a
6063 program should use <tt>fcntl()</tt> first and dot locking
6064 after this or alternatively implement the two locking
6065 methods in a non blocking way<footnote>
6067 If it is not possible to establish both locks, the
6068 system shouldn't wait for the second lock to be
6069 established, but remove the first lock, wait a (random)
6070 time, and start over locking again.</p>
6071 </footnote>. Using the functions <tt>maillock</tt> and
6072 <tt>mailunlock</tt> provided by the
6073 <tt>liblockfile*</tt><footnote>
6075 <tt>liblockfile</tt> version >>1.01</p>
6076 </footnote> packages is the recommended way to realize this.
6080 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6081 unless the user has chosen otherwise. A MUA may remove a
6082 mailbox (unless it has nonstandard permissions) in which
6083 case the MTA or another MUA must recreate it if needed.
6084 Mailboxes must be writable by group mail.</p>
6087 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6088 be setgid mail to do the locking mentioned above (and
6089 must obviously avoid accessing other users' mailboxes
6090 using this privilege).</p>
6093 <tt>/etc/aliases</tt> is the source file for the system mail
6094 aliases (e.g., postmaster, usenet, etc.)--it is the one
6095 which the sysadmin and <tt>postinst</tt> scripts may edit.
6096 After <tt>/etc/aliases</tt> is edited the program or human
6097 editing it must call <prgn>newaliases</prgn>. All MTA
6098 packages must come with a <prgn>newaliases</prgn> program,
6099 even if it does nothing, but older MTA packages do not do
6100 this so programs should not fail if <prgn>newaliases</prgn>
6101 cannot be found.</p>
6104 The convention of writing <tt>forward to
6105 <var>address</var></tt> in the mailbox itself is not
6106 supported. Use a <tt>.forward</tt> file instead.</p>
6109 The <prgn>rmail</prgn> program used by UUCP
6110 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6111 Likewise, <prgn>rsmtp</prgn>, for receiving
6112 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6116 If you need to know what name to use (for example) on
6117 outgoing news and mail messages which are generated locally,
6118 you should use the file <tt>/etc/mailname</tt>. It will
6119 contain the portion after the username and <tt>@</tt> (at)
6120 sign for email addresses of users on the machine (followed
6124 A package should check for the existence of this file. If
6125 it exists it should use it without comment. (An MTA's
6126 prompting configuration script may wish to prompt the user
6127 even if it finds this file exists.) If it does not exist it
6128 should prompt the user for the value and store it in
6129 <tt>/etc/mailname</tt> as well as using it in the package's
6130 configuration. The prompt should make it clear that the
6131 name will not just be used by that package. For example, in
6132 this situation the INN package says:
6134 Please enter the `mail name' of your system. This is the
6135 hostname portion of the address to be shown on outgoing
6136 news and mail messages. The default is
6137 <var>syshostname</var>, your system's host name. Mail
6138 name [`<var>syshostname</var>']:
6140 where <var>syshostname</var> is the output of <tt>hostname
6141 --fqdn</tt>.</p></sect>
6145 <heading>News system configuration</heading>
6148 All the configuration files related to the NNTP (news)
6149 servers and clients should be located under
6150 <tt>/etc/news</tt>.</p>
6153 There are some configuration issues that apply to a number
6154 of news clients and server packages on the machine. These
6158 <tag>/etc/news/organization</tag>
6159 <item><p>A string which should appear as the
6160 organization header for all messages posted
6161 by NNTP clients on the machine</p></item>
6163 <tag>/etc/news/server</tag>
6164 <item><p>Contains the FQDN of the upstream NNTP
6165 server, or localhost if the local machine is
6166 an NNTP server.</p></item>
6169 Other global files may be added as required for cross-package news
6170 configuration.</p></sect>
6174 <heading>Programs for the X Window System</heading>
6177 <em>Programs that may be configured with support for the X Window
6178 System</em> must be configured to do so and must declare any
6179 package dependencies necessary to satisfy their runtime
6180 requirements when using the X Window System, unless the package
6181 in question is of standard or higher priority, in which case
6182 X-specific binaries may be split into a separate package, or
6183 alternative versions of the package with X support may be
6189 <em>Packages which provide an X server</em> that, directly or
6190 indirectly, communicates with real input and display hardware
6191 should declare in their control data that they provide the
6192 virtual package <tt>xserver</tt>.
6195 This implements current practice, and provides an actual
6196 policy for usage of the "xserver" virtual package which
6197 appears in the virtual packages list. In a nutshell, X
6198 servers that interface directly with the display and input
6199 hardware or via another subsystem (e.g., GGI) should provide
6200 xserver. Things like Xvfb, Xnest, and Xprt should not.
6206 <em>Packages that provide a terminal emulator</em> for the X
6207 Window System which support a terminal type with a terminfo
6208 description provided in the <tt>ncurses-base</tt> package
6209 should declare in their control data that they provide the
6210 virtual package <tt>x-terminal-emulator</tt>. They should
6211 also register themselves as an alternative for
6212 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6217 <em>Packages that provide window managers</em> should declare in
6218 their control data that they provide the virtual package
6219 <tt>x-window-manager</tt>. They should also register themselves as an
6220 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6221 calculated as follows:
6223 <item>Start with a priority of 20.</item>
6224 <item>If the window manager supports the Debian menu system,
6225 add 20 points if this support is available in the
6226 package's default configuration (i.e., no
6227 configuration files belonging to the system or user
6228 have to be edited to activate the feature); if
6229 configuration files must be modified, add only 10
6231 <item>If the window manager permits the X session to be
6232 restarted using a <em>different</em> window manager
6233 (without killing the X server) in its default
6234 configuration, add 10 points; otherwise add
6240 <em>Packages that provide fonts for the X Window System</em>
6241 must do a number of things to ensure that they are both
6242 available without modification of the X or font server
6243 configuration, and that they do not corrupt files used by
6244 other font packages to register information about themselves.
6247 Fonts of any type supported by the X Window System
6248 should be be in a separate binary package from any
6249 executables, libraries, or documentation (except that
6250 specific to the fonts shipped); if a program or
6251 library is <em>unusable</em> without one or more
6252 specific fonts, the package containing the program or
6253 library should declare a dependency on the package(s)
6254 containing the font(s) it requires.
6257 BDF fonts should be converted to PCF fonts with the
6258 <tt>bdftopcf</tt> utility (available in the
6259 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6260 placed in a directory that corresponds to their
6264 100 dpi fonts should be placed in
6265 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6268 75 dpi fonts should be placed in
6269 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6272 Character-cell fonts, cursor fonts, and other
6273 low-resolution fonts should be placed in
6274 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6279 Speedo fonts should be placed in
6280 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6283 Type 1 fonts should be placed in
6284 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6285 metric files are available, they may be placed here as
6289 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6290 other than those listed above should be neither created nor
6291 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6292 excepted for historical reasons, but installation of files into
6293 these directories remains discouraged.)
6296 Font packages may, instead of placing files directly in
6297 the X font directories listed above, provide symbolic links in
6298 the font directory which point to the files' actual location
6299 in the filesystem. Such a location should comply with the
6303 Font packages should not contain both 75dpi and 100dpi
6304 versions of a font. If both are available, they should be
6305 provided in separate binary packages with "-75dpi" or "-100dpi"
6306 appended to the names of the packages containing the
6307 corresponding fonts.
6310 Fonts destined for the <tt>misc</tt> subdirectory should
6311 not be included in the same package as 75dpi or 100dpi fonts;
6312 instead, they should be provided in a separate package with
6313 "-misc" appended to its name.
6316 Font packages <em>must not</em> provide the files
6317 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6318 <tt>fonts.scale</tt> in a font directory.
6321 <tt>fonts.dir</tt> files must not be provided at
6325 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6326 files, if needed, should be provided in the
6328 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6329 where <em>fontdir</em> is the name of the
6331 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6332 package's corresponding fonts are stored (e.g.,
6333 <tt>75dpi</tt> or <tt>misc</tt>),
6334 <em>package</em> is the name of the package that
6335 provides these fonts, and <em>extension</em> is
6336 either <tt>scale</tt> or <tt>alias</tt>,
6337 whichever corresponds to the file
6343 Font packages must declare a dependency on
6344 <tt>xutils</tt> and, in the package
6345 post-installation and post-removal scripts, invoke the
6346 <tt>mkfontdir</tt> command on each directory into
6347 which they installed fonts.
6350 Font packages that provide one or more
6351 <tt>fonts.scale</tt> files as described above must declare a
6352 versioned dependency on <tt>xutils (>=
6353 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6354 directory into which they installed fonts
6355 <em>before</em> invoking <tt>mkfontdir</tt> on that
6356 directory. This invocation must occur in both the
6357 post-installation and post-removal scripts.
6360 Font packages that provide one or more
6361 <tt>fonts.alias</tt> files as described above must
6362 declare a versioned dependency on <tt>xutils
6363 (>= 4.0.2)</tt> and, in the package
6364 post-installation and post-removal scripts, invoke
6365 <tt>update-fonts-alias</tt> on each directory into
6366 which they installed fonts.
6369 Font packages must not provide alias names for the
6370 fonts they include which collide with alias names already in
6371 use by fonts already packaged.
6374 Font packages must not provide fonts with the same XLFD
6375 registry name as another font already packaged.
6381 <em>Application defaults</em> files must be installed in the
6382 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6383 localized subdirectory of <tt>/etc/X11/</tt> as described in
6384 the <em>X Toolkit Intrinsics - C Language Interface</em>
6385 manual is also permitted). They must be registered as
6386 <em>conffile</em>s or handled as configuration files. For
6387 programs that are not linked against the X Toolkit (Xt)
6388 library, customization of programs' X resources may also be
6389 supported with the provision of a file with the same name as
6390 that of the package placed in the
6391 <tt>/etc/X11/Xresources/</tt> directory, which must
6392 registered as a <em>conffile</em> or handled as a
6393 configuration file. <em>Important:</em> packages that
6394 install files into the <tt>/etc/X11/Xresources/</tt>
6395 directory <em>must</em> declare a conflict with <tt>xbase
6396 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6397 possible for the installing package to destroy a
6398 previously-existing <tt>/etc/X11/Xresources</tt> file which
6399 had been customized by the system administrator.
6403 <em>Packages using the X Window System should abide by the FHS
6404 standard whenever possible</em>; they should install binaries,
6405 libraries, manual pages, and other files in FHS-mandated
6406 locations wherever possible. This means that files must
6407 not be installed into <tt>/usr/X11R6/bin/</tt>,
6408 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6409 this is necessary for the package to operate properly.
6410 Configuration files for window managers and display managers
6411 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6412 corresponding to the package name due to these programs'
6413 tight integration with the mechanisms of the X Window
6414 System. Application-level programs should use the
6415 <tt>/etc/</tt> directory unless otherwise mandated by
6416 policy. The installation of files into subdirectories of
6417 <tt>/usr/X11R6/include/X11/</tt> and
6418 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6419 package maintainers should determine if subdirectories of
6420 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6421 instead (symlinks from the X11R6 directories to
6422 FHS-compliant locations is encouraged if the program is not
6423 easily configured to look elsewhere for its files).
6424 Packages must not provide -- or install files into -- the
6425 directories <tt>/usr/bin/X11/</tt>,
6426 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6427 Files within a package should, however, make reference to
6428 these directories, rather than their X11R6-named
6429 counterparts <tt>/usr/X11R6/bin/</tt>,
6430 <tt>/usr/X11R6/include/X11/</tt>, and
6431 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6432 referred to have not been moved to FHS-compliant locations.
6436 <em>Programs that require the non-DFSG-compliant OSF/Motif
6437 library</em> should be compiled against and tested with
6438 LessTif (a free re-implementation of Motif) instead. If the
6439 maintainer judges that the program or programs do not work
6440 sufficiently well with LessTif to be distributed and
6441 supported, but do so when compiled against Motif, then two
6442 versions of the package should be created; one linked
6443 statically against Motif and with <tt>-smotif</tt> appended
6444 to the package name, and one linked dynamically against
6445 Motif and with <tt>-dmotif</tt> appended to the package
6446 name. Both Motif-linked versions are dependent upon
6447 non-DFSG-compliant software and thus cannot be uploaded to
6448 the main distribution; if the software is itself
6449 DFSG-compliant it may be uploaded to the contrib
6450 distribution. While known existing versions of OSF/Motif
6451 permit unlimited redistribution of binaries linked against
6452 the library (whether statically or dynamically), it is the
6453 package maintainer's responsibility to determine whether
6454 this is permitted by the license of the copy of OSF/Motif in
6455 his or her possession.
6461 <heading>Emacs lisp programs</heading>
6464 Please refer to the `Debian Emacs Policy' (documented in
6465 <tt>debian-emacs-policy.gz</tt> of the
6466 <prgn>emacsen-common</prgn> package) for details of how to
6467 package emacs lisp programs.</p></sect>
6471 <heading>Games</heading>
6474 The permissions on /var/games are 755
6475 <tt>root.root</tt>.</p>
6478 Each game decides on its own security policy.</p>
6481 Games which require protected, privileged access to
6482 high-score files, savegames, etc., may be made
6483 set-<em>group</em>-id (mode 2755) and owned by
6484 <tt>root.games</tt>, and use files and directories with
6485 appropriate permissions (770 <tt>root.games</tt>, for
6486 example). They must not be made
6487 set-<em>user</em>-id, as this causes security problems. (If
6488 an attacker can subvert any set-user-id game they can
6489 overwrite the executable of any other, causing other players
6490 of these games to run a Trojan horse program. With a
6491 set-group-id game the attacker only gets access to less
6492 important game data, and if they can get at the other
6493 players' accounts at all it will take considerably more
6497 Some packages, for example some fortune cookie programs, are
6498 configured by the upstream authors to install with their
6499 data files or other static information made unreadable so
6500 that they can only be accessed through set-id programs
6501 provided. You should not do this in a Debian package: anyone can
6502 download the <tt>.deb</tt> file and read the data from it,
6503 so there is no point making the files unreadable. Not
6504 making the files unreadable also means that you don't have
6505 to make so many programs set-id, which reduces the risk of a
6509 As described in the FHS, binaries of games should be
6510 installed in the directory <tt>/usr/games</tt>. This also
6511 applies to games that use the X Window System. Manual pages
6512 for games (X and non-X games) should be installed in
6513 <tt>/usr/share/man/man6</tt>.</p>
6517 <chapt><heading>Documentation</heading>
6521 <heading>Manual pages</heading>
6524 You should install manual pages in <prgn>nroff</prgn> source
6525 form, in appropriate places under <tt>/usr/share/man</tt>. You
6526 should only use sections 1 to 9 (see the FHS for more
6527 details). You must not install a preformatted `cat
6531 Each program, utility, and function should have an
6532 associated manpage included in the same package. It is
6533 suggested that all configuration files also have a manual
6534 page included as well.
6538 If no manual page is available for a particular program,
6539 utility, function or configuration file and this is reported as a bug on
6540 debian-bugs, a symbolic link from the requested manual page
6541 to the <manref name="undocumented" section="7"> manual page
6542 may be provided. This symbolic link can be created from
6543 <tt>debian/rules</tt> like this:
6545 ln -s ../man7/undocumented.7.gz \
6546 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6548 This manpage claims that the lack of a manpage has been
6549 reported as a bug, so you may only do this if it really has
6550 (you can report it yourself, if you like). Do not close the
6551 bug report until a proper manpage is available.</p>
6554 You may forward a complaint about a missing manpage to the
6555 upstream authors, and mark the bug as forwarded in the
6556 Debian bug tracking system. Even though the GNU Project do
6557 not in general consider the lack of a manpage to be a bug,
6558 we do--if they tell you that they don't consider it a bug
6559 you should leave the bug in our bug tracking system open
6563 Manual pages should be installed compressed using <tt>gzip
6567 If one manpage needs to be accessible via several names it
6568 is better to use a symbolic link than the <tt>.so</tt>
6569 feature, but there is no need to fiddle with the relevant
6570 parts of the upstream source to change from <tt>.so</tt> to
6571 symlinks--don't do it unless it's easy. You should not create hard
6572 links in the manual page directories, nor put
6573 absolute filenames in <tt>.so</tt> directives. The filename
6574 in a <tt>.so</tt> in a manpage should be relative to the
6575 base of the manpage tree (usually
6576 <tt>/usr/share/man</tt>).</p></sect>
6580 <heading>Info documents</heading>
6583 Info documents should be installed in <tt>/usr/share/info</tt>.
6584 They should be compressed with <tt>gzip -9</tt>.</p>
6587 Your package should call <prgn>install-info</prgn> to update the Info
6589 file, in its post-installation script:
6591 install-info --quiet --section Development Development \
6592 /usr/share/info/foobar.info
6596 It is a good idea to specify a section for the location of
6597 your program; this is done with the <tt>--section</tt>
6598 switch. To determine which section to use, you should look
6599 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6600 relevant (or create a new section if none of the current
6601 sections are relevant). Note that the <tt>--section</tt>
6602 flag takes two arguments; the first is a regular expression
6603 to match (case-insensitively) against an existing section,
6604 the second is used when creating a new one.</p>
6607 You should remove the entries in the pre-removal script:
6609 install-info --quiet --remove /usr/share/info/foobar.info
6613 If <prgn>install-info</prgn> cannot find a description entry
6614 in the Info file you must supply one. See <manref
6615 name="install-info" section="8"> for details.</p>
6619 <heading>Additional documentation</heading>
6622 Any additional documentation that comes with the package may
6623 be installed at the discretion of the package maintainer.
6624 Text documentation should be installed in a directory
6625 <tt>/usr/share/doc/<var>package</var></tt>, where
6626 <var>package</var> is the name of the package, and
6627 compressed with <tt>gzip -9</tt> unless it is small.</p>
6630 If a package comes with large amounts of documentation which
6631 many users of the package will not require you should create
6632 a separate binary package to contain it, so that it does not
6633 take up disk space on the machines of users who do not need
6634 or want it installed.</p>
6637 It is often a good idea to put text information files
6638 (<tt>README</tt>s, changelogs, and so forth) that come with
6639 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6640 in the binary package. However, you don't need to install
6641 the instructions for building and installing the package, of
6645 Files in <tt>/usr/share/doc</tt> should not be referenced by
6646 any program, and the system administrator should be able to
6647 delete them without causing any programs to break. Any files
6648 that are referenced by programs but are also useful as
6649 standalone documentation should be installed under
6650 <tt>/usr/share/<package>/</tt> and symlinked in
6651 <tt>/usr/share/doc/<package>/</tt>.
6657 <heading>Accessing the documentation</heading>
6660 Former Debian releases placed all additional documentation
6661 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6663 <tt>/usr/share/doc/<var>package</var></tt>, each package
6664 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6665 that points to the new location of its documentation in
6666 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6667 symlinks will be removed in the future, but they have to be
6668 there for compatibility reasons until all packages have
6669 moved and the policy is changed accordingly.</footnote>.
6670 The symlink must be created when the package is installed;
6671 it cannot be contained in the package itself due to problems
6672 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6673 this is to put the following in the package's
6674 <prgn>postinst</prgn>:
6676 if [ "$1" = "configure" ]; then
6677 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6678 -a -d /usr/share/doc/#PACKAGE# ]; then
6679 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6683 And the following in the package's <prgn>prerm</prgn>:
6685 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6686 -a -L /usr/doc/#PACKAGE# ]; then
6687 rm -f /usr/doc/#PACKAGE#
6694 <heading>Preferred documentation formats</heading>
6697 The unification of Debian documentation is being carried out
6701 If your package comes with extensive documentation in a
6702 mark up format that can be converted to various other formats
6703 you should if possible ship HTML versions in a binary
6704 package, in the directory
6705 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6708 <p>The rationale: The important thing here is that HTML
6709 docs should be available in <em>some</em> package, not
6710 necessarily in the main binary package, though. </p>
6715 Other formats such as PostScript may be provided at your
6719 <sect id="copyrightfile">
6720 <heading>Copyright information</heading>
6723 Every package must be accompanied by a verbatim copy of its
6724 copyright and distribution license in the file
6725 /usr/share/doc/<package-name>/copyright. This file must
6726 neither be compressed nor be a symbolic link.</p>
6729 In addition, the copyright file must say where the upstream
6730 sources (if any) were obtained, and should explain briefly what
6731 modifications were made in the Debian version of the package
6732 compared to the upstream one. It should name the original
6733 authors of the package and the Debian maintainer(s) who were
6734 involved with its creation.</p>
6737 A copy of the file which will be installed in
6738 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6739 in <tt>debian/copyright</tt>.</p>
6743 /usr/share/doc/<package-name> may be a symbolic link to a
6744 directory in /usr/share/doc only if two packages both come from
6745 the same source and the first package has a "Depends"
6746 relationship on the second. These rules are important
6747 because copyrights must be extractable by mechanical
6751 Packages distributed under the UCB BSD license, the Artistic
6752 license, the GNU GPL, and the GNU LGPL should refer to the
6753 files /usr/share/common-licenses/BSD,
6754 /usr/share/common-licenses/Artistic,
6755 /usr/share/common-licenses/GPL, and
6756 /usr/share/common-licenses/LGPL.
6759 Why "licenses" and not "copyright"? Because
6760 <tt>/usr/doc/copyright</tt> used to contain all the
6761 copyright files, plus the four common licenses GPL,
6762 LGPL, Artistic and BSD. Now individual copyright files
6763 for packages are no longer in a common directory. Once
6764 <tt>/usr/doc/copyright</tt> is almost empty it makes
6765 sense to rename "copyright" to "licenses"
6768 Why "common-licenses" and not "licenses"? Because if I
6769 put just "licenses" I'm sure I will receive a bug report
6770 saying "license foo is not included in the licenses
6771 directory. They are not all the licenses, just a few
6772 common ones. I could use /usr/share/doc/common-licenses
6773 but I think this is too long, and, after all, the GPL
6774 does not "document" anything, it is merely a license.
6780 You should not use the copyright file as a general <tt>README</tt>
6781 file. If your package has such a file it should be
6782 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6783 <tt>README.Debian</tt> or some other appropriate place.</p>
6787 <heading>Examples</heading>
6790 Any examples (configurations, source files, whatever),
6791 should be installed in a directory
6792 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6793 files should not be referenced by any program--they're there
6794 for the benefit of the system administrator and users, as
6795 documentation only. Architecture-specific example files
6796 should be installed in a directory
6797 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6798 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6799 to files in it. Or the latter directory may be a symlink to
6803 <sect id="instchangelog">
6804 <heading>Changelog files</heading>
6807 Packages that are not Debian-native must contain a copy of
6808 <tt>debian/changelog</tt> file from the Debian source tree
6809 in <tt>/usr/share/doc/<var>package</var></tt> as
6810 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6811 available, it should be accessible as
6812 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6813 plain text. If the upstream changelog is distributed in
6814 HTML, it should be made available in that form as
6815 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6816 and the <tt>changelog.gz</tt> should be generated using, eg,
6817 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6818 do not already conform to this naming convention, then this
6819 may be achieved either by renaming the files, or adding a
6820 symbolic link, at the maintainer's discretion.
6823 Rationale: People should not have to look into two
6824 places for upstream changelogs merely because they are
6832 All these files should be installed compressed using <tt>gzip -9</tt>,
6833 as they will become large with time even if they start out
6838 If the package has only one changelog which is used both as
6839 the Debian changelog and the upstream one because there is
6840 no separate upstream maintainer then that changelog should
6841 usually be installed as
6842 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6843 there is a separate upstream maintainer, but no upstream
6844 changelog, then the Debian changelog should still be called
6845 <tt>changelog.Debian.gz</tt>.</p>