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8 Debian GNU/Linux Policy Manual.
9 Copyright (C)1996,1997,1998 Ian Jackson and Christian Schwarz;
10 released under the terms of the GNU
11 General Public License, version 2 or (at your option) any later.
12 Initial version 1996, Ian Jackson, ijackson@gnu.ai.mit.edu
13 Revised November 27, 1996, David A. Morris, bweaver@debian.org
14 New sections March 15, 1997, Christian Schwarz, schwarz@debian.org
15 Reworked/Restructured April-July 1997, Christian Schwarz, schwarz@debian.org
16 Maintainer since 1997, Christian Schwarz, schwarz@debian.org
17 Christoph Lameter contributed the "Web Standard"
18 The debian-policy mailing list has taken responsibility for the
19 contents of this document since September 1998, with the package
20 maintainers responsible for packaging administrivia only.
25 <title>Debian Policy Manual</title>
27 <name>Ian Jackson </name>
28 <email>ijackson@gnu.ai.mit.edu</email>
31 <name>Christian Schwarz</name>
32 <email>schwarz@debian.org</email>
35 <name>revised: David A. Morris</name>
36 <email>bweaver@debian.org</email>
39 <name>The Debian Policy mailing List</name>
40 <email>debian-policy@lists.debian.org</email>
42 <version>version &version;, &date;</version>
45 This manual describes the policy requirements for the Debian
46 GNU/Linux distribution. This includes the structure and
47 contents of the Debian archive and several design issues of the
48 operating system, as well as technical requirements that each
49 package must satisfy to be included in the distribution. The
50 policy package itself is maintained by a group of maintainers
51 that have no editorial powers. At the moment, the list of
55 <p>Julian Gilbey <email>jdg@debian.org</email></p>
58 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
66 Copyright ©1996,1997,1998 Ian Jackson
67 and Christian Schwarz.
70 This manual is free software; you may redistribute it and/or
71 modify it under the terms of the GNU General Public License
72 as published by the Free Software Foundation; either version
73 2, or (at your option) any later version.
77 This is distributed in the hope that it will be useful, but
78 <em>without any warranty</em>; without even the implied
79 warranty of merchantability or fitness for a particular
80 purpose. See the GNU General Public License for more
85 A copy of the GNU General Public License is available as
86 <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
87 distribution or on the World Wide Web at
88 <url id="http://www.gnu.org/copyleft/gpl.html"
89 name="The GNU General Public Licence">. You can also
90 obtain it by writing to the Free Software Foundation, Inc.,
91 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
99 <heading>About this manual</heading>
101 <heading>Scope</heading>
103 This manual describes the policy requirements for the Debian
104 GNU/Linux distribution. This includes the structure and
105 contents of the Debian archive and several design issues of the
106 operating system, as well as technical requirements that
107 each package must satisfy to be included in the
113 This manual also describes Debian policy as it relates to
114 creating Debian packages. It is not a tutorial on how to build
115 packages, nor is it exhaustive where it comes to describing
116 the behavior of the packaging system. Instead, this manual
117 attempts to define the interface to the package management
118 system that the developers have to be conversant with.
121 Informally, the criteria used for inclusion is that the
122 material meet one of the following requirements:
124 <tag>Standard interfaces</tag>
127 The material presented represents an interface to
128 the packaging system that is mandated for use, and
129 is used by, a significant number of packages, and
130 therefore should not be changed without peer
131 review. Package maintainers can then rely on this
132 interfaces not changing, and the package
133 management software authors need to ensure
134 compatibility with these interface
135 definitions. (Control file and 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>
4057 <heading>The system-wide mail directory</heading>
4059 The system-wide mail directory is <tt>/var/mail</tt>. This
4060 directory is part of the base system and should not owned
4061 by any particular mail agents. The use of the old
4062 location <tt>/var/spool/mail</tt> is deprecated, even
4063 though the spool may still be physically located there.
4064 To maintain partial upgrade compatibility for systems
4065 which have <tt>/var/spool/mail</tt> as their physical mail
4066 spool, packages using <tt>/var/mail</tt> must depend on
4067 either <package>libc6</package> (>= 2.1.3-13), or on
4068 <package>base-files</package> (>= 2.2.0), or on later
4069 versions of either one of these packages.
4078 <heading>Users and groups</heading>
4081 The Debian system can be configured to use either plain or
4082 shadow passwords.</p>
4085 Some user ids (UIDs) and group ids (GIDs) are reserved
4086 globally for use by certain packages. Because some packages
4087 need to include files which are owned by these users or
4088 groups, or need the ids compiled into binaries, these ids
4089 must be used on any Debian system only for the purpose for
4090 which they are allocated. This is a serious restriction, and
4091 we should avoid getting in the way of local administration
4092 policies. In particular, many sites allocate users and/or
4093 local system groups starting at 100.</p>
4096 Apart from this we should have dynamically allocated ids,
4097 which should by default be arranged in some sensible
4098 order--but the behavior should be configurable.</p>
4101 Packages other than <tt>base-passwd</tt> must not modify
4102 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4103 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4106 The UID and GID ranges are as follows:
4111 Globally allocated by the Debian project, the
4112 same on every Debian system. These ids will appear in
4113 the <tt>passwd</tt> and <tt>group</tt> files of all
4114 Debian systems, new ids in this range being added
4115 automatically as the <tt>base-passwd</tt> package is
4119 Packages which need a single statically allocated uid
4120 or gid should use one of these; their maintainers
4121 should ask the <tt>base-passwd</tt> maintainer for
4128 Dynamically allocated system users and groups.
4129 Packages which need a user or group, but can have this
4130 user or group allocated dynamically and differently on
4131 each system, should use `<tt>adduser --system</tt>' to
4132 create the group and/or user. <prgn>adduser</prgn>
4133 will check for the existence of the user or group, and
4134 if necessary choose an unused id based on the ranges
4135 specified in <tt>adduser.conf</tt>.</p></item>
4138 <tag>1000-29999:</tag>
4141 Dynamically allocated user accounts. By default
4142 <prgn>adduser</prgn> will choose UIDs and GIDs for
4143 user accounts in this range, though
4144 <tt>adduser.conf</tt> may be used to modify this
4148 <tag>30000-59999:</tag>
4150 <p>Reserved.</p></item>
4153 <tag>60000-64999:</tag>
4156 Globally allocated by the Debian project, but only
4157 created on demand. The ids are allocated centrally and
4158 statically, but the actual accounts are only created
4159 on users' systems on demand.</p>
4162 These ids are for packages which are obscure or which
4163 require many statically-allocated ids. These packages
4164 should check for and create the accounts in
4165 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4166 <prgn>adduser</prgn> if it has this facility) if
4167 necessary. Packages which are likely to require
4168 further allocations should have a `hole' left after
4169 them in the allocation, to give them room to
4173 <tag>65000-65533:</tag>
4175 <p>Reserved.</p></item>
4180 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4181 to the group `<tt>nogroup</tt>.'</p></item>
4187 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4188 because it is the error return sentinel value.</p>
4193 <sect id="sysvinit">
4194 <heading>System run levels</heading>
4197 <sect1 id="/etc/init.d">
4198 <heading>Introduction</heading>
4201 The <tt>/etc/init.d</tt> directory contains the scripts
4202 executed by <prgn>init</prgn> at boot time and when init
4203 state (or `runlevel') is changed (see <manref name="init"
4207 There are at least two different, yet functionally
4208 equivalent, ways of handling these scripts. For the sake
4209 of simplicity, this document describes only the symbolic
4210 link method. However, it must not be assumed by maintainer
4211 scripts that this method is being used, and any automated
4212 manipulation of the various runlevel behaviours by
4213 maintainer scripts must be performed using `update-rc.d'
4214 as described below and not by manually installing or
4215 removing symlinks. For information on the
4216 implementation details of the other method, implemented in
4217 the <tt>file-rc</tt> package, please refer to the
4218 documentation of that package.</p>
4221 These scripts are referenced by symbolic links in
4222 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4223 changing runlevels, <prgn>init</prgn> looks in the
4224 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4225 it should execute, where <var>n</var> is the runlevel that
4226 is being changed to, or `S' for the boot-up scripts.</p>
4229 The names of the links all have the form
4230 <tt>S<var>mm</var><var>script</var></tt> or
4231 <tt>K<var>mm</var><var>script</var></tt> where
4232 <var>mm</var> is a two-digit number and <var>script</var>
4233 is the name of the script (this should be the same as the
4234 name of the actual script in <tt>/etc/init.d</tt>.</p>
4237 When <prgn>init</prgn> changes runlevel first the targets
4238 of the links whose names starting with a <tt>K</tt> are
4239 executed, each with the single argument <tt>stop</tt>,
4240 followed by the scripts prefixed with an <tt>S</tt>, each
4241 with the single argument <tt>start</tt>. The <tt>K</tt>
4242 links are responsible for killing services and the
4243 <tt>S</tt> link for starting services upon entering the
4247 For example, if we are changing from runlevel 2 to
4248 runlevel 3, init will first execute all of the <tt>K</tt>
4249 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4250 all of the <tt>S</tt> prefixed scripts. The links
4251 starting with <tt>K</tt> will cause the referred-to file
4252 to be executed with an argument of <tt>stop</tt>, and the
4253 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4256 The two-digit number <var>mm</var> is used to decide which
4257 order to start and stop things in--low-numbered links have
4258 their scripts run first. For example, the <tt>K20</tt>
4259 scripts will be executed before the <tt>K30</tt> scripts.
4260 This is used when a certain service must be started before
4261 another. For example, the name server <prgn>bind</prgn>
4262 might need to be started before the news server
4263 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4264 access lists. In this case, the script that starts
4265 <prgn>bind</prgn> would have a lower number than the
4266 script that starts <prgn>inn</prgn> so that it runs first:
4275 <heading>Writing the scripts</heading>
4278 Packages that include daemons for system services should
4279 place scripts in <tt>/etc/init.d</tt> to start or stop
4280 services at boot time or during a change of runlevel.
4281 These scripts should be named
4282 <tt>/etc/init.d/<var>package</var></tt>, and they should
4283 accept one argument, saying what to do:
4286 <tag><tt>start</tt></tag>
4287 <item><p>start the service,</p></item>
4289 <tag><tt>stop</tt></tag>
4290 <item><p>stop the service,</p></item>
4292 <tag><tt>restart</tt></tag>
4293 <item><p>stop and restart the service,</p></item>
4295 <tag><tt>reload</tt></tag>
4296 <item><p>cause the configuration of the service to be
4297 reloaded without actually stopping and restarting
4298 the service,</p></item>
4300 <tag><tt>force-reload</tt></tag> <item><p>cause the
4301 configuration to be reloaded if the service supports
4302 this, otherwise restart the service.</p></item>
4305 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4306 <tt>force-reload</tt> options should be supported by all
4307 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4308 option is optional.</p>
4311 The <tt>init.d</tt> scripts should ensure that they will
4312 behave sensibly if invoked with <tt>start</tt> when the
4313 service is already running, or with <tt>stop</tt> when it
4314 isn't, and that they don't kill unfortunately-named user
4315 processes. The best way to achieve this is usually to use
4316 <prgn>start-stop-daemon</prgn>.</p>
4319 If a service reloads its configuration automatically (as
4320 in the case of <prgn>cron</prgn>, for example), the
4321 <tt>reload</tt> option of the <tt>init.d</tt> script
4322 should behave as if the configuration has been reloaded
4326 These scripts should not fail obscurely when the
4327 configuration files remain but the package has been
4328 removed, as configuration files remain on the system after
4329 the package has been removed. Only when <prgn>dpkg</prgn>
4330 is executed with the <tt>--purge</tt> option will
4331 configuration files be removed. In particular, the init
4332 script itself is usually a configuration file (see
4333 <ref id="init.d notes">), and will remain on the system if
4334 the package is removed but not purged. Therefore, you
4335 should include a <tt>test</tt> statement at the top of the
4338 test -f <var>program-executed-later-in-script</var> || exit 0
4342 Often there are some values in the `<tt>init.d</tt>'
4343 scripts that a system administrator will frequently want
4344 to change. While the scripts are frequently conffiles,
4345 modifying them requires that the administrator merge in
4346 their changes each time the package is upgraded and the
4347 conffile changes. To ease the burden on the system
4348 administrator, such configurable values should not be
4349 placed directly in the script. Instead, they should be
4350 placed in a file in `<tt>/etc/default</tt>', which
4351 typically will have the same base name as the
4352 `<tt>init.d</tt>' script. This extra file can be sourced
4353 by the script when the script runs. It must contain only
4354 variable settings and comments.
4358 To ensure that vital configurable values are always
4359 available, the `<tt>init.d</tt>' script should set default
4360 values for each of the shell variables it uses before
4361 sourcing the <tt>/etc/default/</tt> file. Also, since the
4362 `<tt>/etc/default/</tt>' file is often a conffile, the
4363 `<tt>init.d</tt>' script must behave sensibly without
4364 failing if it is deleted.
4370 <heading>Managing the links</heading>
4373 The program <prgn>update-rc.d</prgn> is provided to make
4374 it easier for package maintainers to arrange for the
4375 proper creation and removal of
4376 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4377 functional equivalent if another method is being used.
4378 This may be used by maintainers in their packages'
4379 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4382 You must use this script to make changes to
4383 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4384 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4385 in the actual archive or manually create or remove the
4386 symbolic links in maintainer scripts. (The latter will
4387 fail if an alternative method of maintaining runlevel
4388 information is being used.)</p>
4391 By default <prgn>update-rc.d</prgn> will start services in
4392 each of the multi-user state runlevels (2, 3, 4, and 5)
4393 and stop them in the halt runlevel (0), the single-user
4394 runlevel (1) and the reboot runlevel (6). The system
4395 administrator will have the opportunity to customize
4396 runlevels by either running <prgn>update-rc.d</prgn>, by
4397 simply adding, moving, or removing the symbolic links in
4398 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4399 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4400 <tt>file-rc</tt> method is being used.</p>
4403 To get the default behavior for your package, put in your
4404 <tt>postinst</tt> script
4406 update-rc.d <var>package</var> defaults >/dev/null
4408 and in your <tt>postrm</tt>
4410 if [ purge = "$1" ]; then
4411 update-rc.d <var>package</var> remove >/dev/null
4416 This will use a default sequence number of 20. If it does
4417 not matter when or in which order the script is run, use
4418 this default. If it does, then you should talk to the
4419 maintainer of the <prgn>sysvinit</prgn> package or post to
4420 <tt>debian-devel</tt>, and they will help you choose a
4424 For more information about using <tt>update-rc.d</tt>,
4425 please consult its manpage <manref name="update-rc.d"
4426 section="8">.</p></sect1>
4430 <heading>Boot-time initialization</heading>
4433 There used to be another directory, <tt>/etc/rc.boot</tt>,
4434 which contained scripts which were run once per machine
4435 boot. This has been deprecated in favour of links from
4436 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4437 described in <ref id="/etc/init.d">. Packages must not
4438 place files in <tt>/etc/rc.boot</tt>.</p>
4440 <sect1 id="init.d notes">
4441 <heading>Notes</heading>
4444 <em>Do not</em> include the
4445 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4446 <tt>.deb</tt> file system archive! <em>This will cause
4447 problems!</em> You must create them with
4448 <prgn>update-rc.d</prgn>, as above.</p>
4451 <em>Do not</em> include the
4452 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4453 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4454 problems!</em> You should, however, treat the
4455 <tt>/etc/init.d</tt> scripts as configuration files,
4456 either by marking them as conffiles or managing them
4457 correctly in the maintainer scripts (see
4458 <ref id="config files">). (This is important since we want
4459 to give the local system administrator the chance to adapt
4460 the scripts to the local system--e.g., to disable a
4461 service without de-installing the package, or to specify
4462 some special command line options when starting a
4463 service--while making sure her changes aren't lost during
4464 the next package upgrade.)</p>
4468 <heading>Example</heading>
4471 The <prgn>bind</prgn> DNS (nameserver) package wants to
4472 make sure that the nameserver is running in multiuser
4473 runlevels, and is properly shut down with the system. It
4474 puts a script in <tt>/etc/init.d</tt>, naming the script
4475 appropriately <tt>bind</tt>. As you can see, the script
4476 interprets the argument <tt>reload</tt> to send the
4477 nameserver a <tt>HUP</tt> signal (causing it to reload its
4478 configuration); this way the user can say
4479 <tt>/etc/init.d/bind reload</tt> to reload the name
4480 server. The script has one configurable value, which can
4481 be used to pass parameters to the named program at
4489 # Original version by Robert Leslie
4490 # <rob@mars.org>, edited by iwj and cs
4492 test -x /usr/sbin/named || exit 0
4494 # Source defaults file.
4496 if [ -f /etc/default/bind ]; then
4503 echo -n "Starting domain name service: named"
4504 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4509 echo -n "Stopping domain name service: named"
4510 start-stop-daemon --stop --quiet \
4511 --pidfile /var/run/named.pid --exec /usr/sbin/named
4515 echo -n "Restarting domain name service: named"
4516 start-stop-daemon --stop --quiet \
4517 --pidfile /var/run/named.pid --exec /usr/sbin/named
4518 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4522 force-reload|reload)
4523 echo -n "Reloading configuration of domain name service: named"
4524 start-stop-daemon --stop --signal 1 --quiet \
4525 --pidfile /var/run/named.pid --exec /usr/sbin/named
4529 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4539 Complementing the above init script is a file
4540 '<tt>/etc/default/bind</tt>', which contains configurable
4541 parameters used by the script.
4545 # Specified parameters to pass to named. See named(8).
4546 # You may uncomment the following line, and edit to taste.
4552 Another example on which to base your <tt>/etc/init.d</tt>
4553 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4556 If this package is happy with the default setup from
4557 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4558 and having named running in all runlevels, it can say in
4559 its <tt>postinst</tt>:
4561 update-rc.d bind defaults >/dev/null
4563 And in its <tt>postrm</tt>, to remove the links when the
4566 if [ purge = "$1" ]; then
4567 update-rc.d bind remove >/dev/null
4573 <heading>Cron jobs</heading>
4576 Packages must not modify the configuration file
4577 <tt>/etc/crontab</tt>, and they must not modify the files in
4578 <tt>/var/spool/cron/crontabs</tt>.</p>
4581 If a package wants to install a job that has to be executed
4582 via cron, it should place a file with the name of the
4583 package in one of the following directories:
4589 As these directory names imply, the files within them are
4590 executed on a daily, weekly, or monthly basis,
4591 respectively. The exact times are listed in
4592 <tt>/etc/crontab</tt>.</p>
4595 All files installed in any of these directories must be
4596 scripts (shell scripts, Perl scripts, etc.) so that they can
4597 easily be modified by the local system administrator. In
4598 addition, they should be treated as configuration files.</p>
4601 If a certain job has to be executed more frequently than
4602 daily, the package should install a file
4603 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4604 the same syntax as <tt>/etc/crontab</tt> and is processed by
4605 <prgn>cron</prgn> automatically. The file must also be
4606 treated as a configuration file. (Note, that entries in the
4607 <tt>/etc/cron.d</tt> directory are not handled by
4608 <prgn>anacron</prgn>. Thus, you should only use this
4609 directory for jobs which may be skipped if the system is not
4613 The scripts or crontab entries in these directories should
4614 check if all necessary programs are installed before they
4615 try to execute them. Otherwise, problems will arise when a
4616 package was removed but not purged since configuration files
4617 are kept on the system in this situation.</p>
4621 <heading>Console messages</heading>
4624 This section describes different formats for messages
4625 written to standard output by the <tt>/etc/init.d</tt>
4626 scripts. The intent is to improve the consistency of
4627 Debian's startup and shutdown look and feel.</p>
4630 Please look very careful at the details. We want to get the
4631 messages to look exactly the same way concerning spaces,
4632 punctuation, and case of letters.</p>
4635 Here is a list of overall rules that you should use when you
4636 create output messages. They can be useful if you have a
4637 non-standard message that isn't covered in the sections
4644 Every message should cover one line, start with a
4645 capital letter and end with a period `.'.</p></item>
4650 If you want to express that the computer is working on
4651 something (performing a specific task, not starting or
4652 stopping a program), we use an ``ellipsis'', namely
4653 three dots `...'. Note that we don't insert spaces in
4654 front of or behind the dots. If the task has been
4655 completed we write `done.' and a line feed.</p></item>
4660 Design your messages as if the computer is telling you
4661 what he is doing (let him be polite :-) but don't
4662 mention ``him'' directly. For example, if you think
4665 I'm starting network daemons: nfsd mountd.
4669 Starting network daemons: nfsd mountd.
4670 </example></p></item>
4674 The following formats should be used</p>
4679 <p>when daemons get started.</p>
4682 Use this format if your script starts one or more
4683 daemons. The output should look like this (a single
4684 line, no leading spaces):
4686 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4688 The <description> should describe the subsystem
4689 the daemon or set of daemons are part of, while
4690 <daemon-1> up to <daemon-n> denote each
4691 daemon's name (typically the file name of the
4695 For example, the output of /etc/init.d/lpd would look like:
4697 Starting printer spooler: lpd.
4701 This can be achieved by saying
4703 echo -n "Starting printer spooler: lpd"
4704 start-stop-daemon --start --quiet lpd
4707 in the script. If you have more than one daemon to
4708 start, you should do the following:
4710 echo -n "Starting remote file system services:"
4711 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4712 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4713 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4716 This makes it possible for the user to see what takes
4717 so long and when the final daemon has been
4718 started. You should be careful where to put spaces: In the
4719 example above the system administrator can easily
4720 comment out a line if he don't wants to start a
4721 specific daemon, while the displayed message still
4722 looks good.</p></item>
4726 <p>when something needs to be configured.</p>
4729 If you have to set up different parameters of the
4730 system upon boot up, you should use this format:
4732 Setting <parameter> to `<value>'.
4736 You can use the following echo statement to get the quotes right:
4738 echo "Setting DNS domainname to \`"value"'."
4742 Note that the left quotation mark (`) is different
4743 from the right (').</p></item>
4746 <p>when a daemon is stopped.</p>
4749 When you stop a daemon you should issue a message
4750 similar to the startup message, except that `Starting'
4751 is replaced with `Stopping'.</p>
4754 So stopping the printer daemon will like like this:
4756 Stopping printer spooler: lpd.
4757 </example></p></item>
4760 <p>when something is executed.</p>
4763 There are several examples where you have to run a
4764 program at system startup or shutdown to perform a
4765 specific task. For example, setting the system's clock
4766 via `netdate' or killing all processes when the system
4767 comes down. Your message should like this:
4769 Doing something very useful...done.
4771 You should print the `done.' right after the job has been completed,
4772 so that the user gets informed why he has to wait. You can get this
4775 echo -n "Doing something very useful..."
4779 in your script.</p></item>
4782 <p>when the configuration is reloaded.</p>
4785 When a daemon is forced to reload its configuration
4786 files you should use the following format:
4788 Reloading <daemon's-name> configuration...done.
4789 </example></p></item>
4792 <p>when none of the above rules apply.</p>
4795 If you have to print a message that doesn't fit into
4796 the styles described above, you can use something
4797 appropriate, but please have a look at the overall
4798 rules listed above.</p></item>
4803 <heading>Menus</heading>
4806 Menu entries should follow the current menu policy as
4807 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4808 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4809 or your local mirror. In addition, it is included in the
4810 <tt>debian-policy</tt> package.
4814 The Debian <tt>menu</tt> packages provides a unique
4815 interface between packages providing applications and
4816 documents, and <em>menu programs</em> (either X window
4817 managers or text-based menu programs as
4818 <prgn>pdmenu</prgn>).</p>
4821 All packages that provide applications that need not be
4822 passed any special command line arguments for normal
4823 operation should register a menu entry for those
4824 applications, so that users of the <tt>menu</tt> package
4825 will automatically get menu entries in their window
4826 managers, as well in shells like <tt>pdmenu</tt>.</p>
4829 Please refer to the <em>Debian Menu System</em> document
4830 that comes with the <tt>menu</tt> package for information
4831 about how to register your applications and web
4837 <heading>Multimedia handlers</heading>
4840 Packages which provide the ability to view/show/play,
4841 compose, edit or print MIME types should register themselves
4842 as such following the current MIME support policy as defined
4843 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4844 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4845 or your local mirror. In addition, it is included in the
4846 <tt>debian-policy</tt> package.
4850 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4851 mechanism for encoding files and data streams and providing
4852 meta-information about them, in particular their type (e.g.
4853 audio or video) and format (e.g. PNG, HTML, MP3).
4857 Registration of MIME type handlers allows programs like mail
4858 user agents and web browsers to to invoke these handlers to
4859 view, edit or display MIME types they don't support
4865 <heading>Keyboard configuration</heading>
4868 To achieve a consistent keyboard configuration (i.e., all
4869 applications interpret a keyboard event the same way) all
4870 programs in the Debian distribution must be configured to
4871 comply with the following guidelines.</p>
4874 Here is a list that contains certain keys and their interpretation:
4877 <tag><tt><--</tt></tag>
4878 <item><p>delete the character to the left of the cursor</p></item>
4880 <tag><tt>Delete</tt></tag>
4881 <item><p>delete the character to the right of the cursor</p></item>
4883 <tag><tt>Control+H</tt></tag>
4884 <item><p>emacs: the help prefix</p></item>
4887 The interpretation of any keyboard events should be independent
4888 of the terminal that's used, be it a virtual console, an X
4889 terminal emulator, an rlogin/telnet session, etc.</p>
4892 The following list explains how the different programs
4893 should be set up to achieve this:</p>
4896 <list compact="compact">
4897 <item><p>`<tt><--</tt>' generates KB_Backspace in
4900 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4904 X translations are set up to make KB_Backspace
4905 generate ASCII DEL, and to make KB_Delete generate
4906 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4907 the `delete character' key). This must be done by
4908 loading the resources using xrdb on all local X
4909 displays, not using the application defaults, so that
4910 the translation resources used correspond to the
4911 xmodmap settings.</p></item>
4915 The Linux console is configured to make
4916 `<tt><--</tt>' generate DEL, and `Delete' generate
4917 <tt>ESC [ 3 ~</tt> (this is the case at the
4921 X applications are configured so that Backspace
4922 deletes left, and Delete deletes right. Motif
4923 applications already work like this.</p></item>
4925 <item><p>stty erase <tt>^?</tt> .</p></item>
4928 The `xterm' terminfo entry should have <tt>ESC [ 3
4929 ~</tt> for kdch1, just like TERM=linux and
4930 TERM=vt220.</p></item>
4933 Emacs is programmed to map KB_Backspace or the `stty
4934 erase' character to delete-backward-char, and
4935 KB_Delete or kdch1 to delete-forward-char, and
4936 <tt>^H</tt> to help as always.</p></item>
4939 Other applications use the `stty erase' character and
4940 kdch1 for the two delete keys, with ASCII DEL being
4941 `delete previous character' and kdch1 being `delete
4942 character under cursor'.</p></item>
4946 This will solve the problem except for:</p>
4949 <list compact="compact">
4951 Some terminals have a <tt><--</tt> key that cannot
4952 be made to produce anything except <tt>^H</tt>. On
4953 these terminals Emacs help will be unavailable on
4954 <tt>^H</tt> (assuming that the `stty erase' character
4955 takes precedence in Emacs, and has been set
4956 correctly). M-x help or F1 (if available) can be used
4960 Some operating systems use <tt>^H</tt> for stty erase.
4961 However, modern telnet versions and all rlogin
4962 versions propagate stty settings, and almost all UNIX
4963 versions honour stty erase. Where the stty settings
4964 are not propagated correctly things can be made to
4965 work by using stty manually.</p></item>
4968 Some systems (including previous Debian versions) use
4969 xmodmap to arrange for both <tt><--</tt> and Delete
4970 to generate KB_Delete. We can change the behavior
4971 of their X clients via the same X resources that we
4972 use to do it for our own, or have our clients be
4973 configured via their resources when things are the
4974 other way around. On displays configured like this
4975 Delete will not work, but <tt><--</tt>
4979 Some operating systems have different kdch1 settings
4980 in their terminfo for xterm and others. On these
4981 systems the Delete key will not work correctly when
4982 you log in from a system conforming to our policy, but
4983 <tt><--</tt> will.</p></item>
4990 <heading>Environment variables</heading>
4993 A program must not depend on environment variables to get
4994 reasonable defaults. (That's because these environment
4995 variables would have to be set in a system-wide
4996 configuration file like /etc/profile, which is not supported
5000 If a program usually depends on environment variables for its
5001 configuration, the program should be changed to fall back to
5002 a reasonable default configuration if these environment
5003 variables are not present. If this cannot be done easily
5004 (e.g., if the source code of a non-free program is not
5005 available), the program must be replaced by a small
5006 `wrapper' shell script which sets the environment variables
5007 if they are not already defined, and calls the original program.</p>
5010 Here is an example of a wrapper script for this purpose:
5014 BAR=${BAR:-/var/lib/fubar}
5016 exec /usr/lib/foo/foo "$@"
5020 Furthermore, as <tt>/etc/profile</tt> is a configuration
5021 file of the <prgn>base-files</prgn> package, other packages must not
5022 put any environment variables or other commands into that
5027 <heading>Files</heading>
5031 <heading>Binaries</heading>
5034 Two different packages must not install programs with
5035 different functionality but with the same filenames. (The
5036 case of two programs having the same functionality but
5037 different implementations is handled via `alternatives.')
5038 If this case happens, one of the programs must be
5039 renamed. The maintainers should report this to the
5040 developers' mailing and try to find a consensus about
5041 which package will have to be renamed. If a consensus can
5042 not be reached, <em>both</em> programs must be
5046 Generally the following compilation parameters should be used:
5049 CFLAGS = -O2 -Wall # sane warning options vary between programs
5051 install -s # (or use strip on the files in debian/tmp)
5055 Note that by default all installed binaries should be stripped,
5056 either by using the <tt>-s</tt> flag to
5057 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5058 the binaries after they have been copied into
5059 <tt>debian/tmp</tt> but before the tree is made into a
5063 The <tt>-N</tt> flag should not be used. On a.out systems
5064 it may have been useful for some very small binaries, but
5065 for ELF it has no good effect.</p>
5068 Debugging symbols are useful for error diagnosis,
5069 investigation of core dumps (which may be submitted by users
5070 in bug reports), or testing and developing the
5071 software. Therefore it is recommended to support building
5072 the package with debugging information through the following
5073 interface: If the environment variable
5074 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5075 <tt>debug</tt>, compile the software with debugging
5076 information (usually this involves adding the <tt>-g</tt>
5077 flag to <tt>CFLAGS</tt>). This allows the generation of a
5078 build tree with debugging information. If the environment
5079 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5080 <tt>nostrip</tt>, do not strip the files at installation
5081 time. This allows one to generate a package with debugging
5082 information included. The following makefile snippet is only
5083 an example of how one may test for either condition:
5086 Rationale: Building by default with -g causes more
5087 wasted CPU cycles since the information is stripped away
5088 anyway. The package can by default build without -g if
5089 it also provides a mechanism to easily be rebuilt with
5090 debugging information. This can be done by providing a
5091 "build-debug" make target, or allowing the user to
5092 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5093 compiling that package.
5095 <p>Now this has several added benefits:
5099 It is actually easier to build debugging bins and
5100 libraries this way (no more editing debian/rules
5101 or similar) since it provides a documented way of
5102 getting this type of build.</p>
5106 There will be much less wasted CPU time for the
5107 autobuilders since not having debugging
5108 information (and hence also not having to strip
5109 it) will increase the speed of compiles. This
5110 skips an entire pass of the compiler.
5121 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5122 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5123 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5124 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5126 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5129 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5130 INSTALL_PROGRAM += -s
5134 Please note that the above example is merely informative,
5135 and is not a policy mandate. You may have to massage this
5136 example in order to make it work for your package.
5141 It is up to the package maintainer to decide what
5142 compilation options are best for the package. Certain
5143 binaries (such as computationally-intensive programs) will
5144 function better with certain flags (<tt>-O3</tt>, for
5145 example); feel free to use them. Please use good judgment
5146 here. Don't use flags for the sake of it; only use them
5147 if there is good reason to do so. Feel free to override
5148 the upstream author's ideas about which compilation
5149 options are best--they are often inappropriate for our
5150 environment.</p></sect>
5154 <heading>Libraries</heading>
5157 All libraries must have a shared version in the lib
5158 package and a static version in the lib-dev package. The
5159 shared version must be compiled with <tt>-fPIC</tt>, and
5160 the static version must not be. In other words, each
5161 <tt>*.c</tt> file will need to be compiled twice.</p>
5164 You must specify the gcc option <tt>-D_REENTRANT</tt>
5165 when building a library (either static or shared) to make
5166 the library compatible with LinuxThreads.</p>
5169 Note that all installed shared libraries should be
5172 strip --strip-unneeded <your-lib>
5174 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5175 only the symbols which aren't needed for relocation
5176 processing.) Shared libraries can function perfectly well
5177 when stripped, since the symbols for dynamic linking are
5178 in a separate part of the ELF object file.</p>
5181 Note that under some circumstances it may be useful to
5182 install a shared library unstripped, for example when
5183 building a separate package to support debugging.
5187 An ever increasing number of packages are using libtool to
5188 do their linking. The latest GNU libtools (>= 1.3a) can take
5189 advantage of the metadata in the installed libtool archive
5190 files (`*.la'). The main advantage of libtool's .la files is
5191 that it allows libtool to store and subsequently access
5192 metadata with respect to the libraries it builds. libtool
5193 will search for those files, which contain a lot of useful
5194 information about a library (e.g. dependency libraries for
5195 static linking). Also, they're <em>essential</em> for
5196 programs using libltdl.
5200 Certainly libtool is fully capable of linking against shared
5201 libraries which don't have .la files, but being a mere shell
5202 script it can add considerably to the build time of a
5203 libtool using package if that shell-script has to derive all
5204 this information from first principles for each library every
5205 time it is linked. With the advent of libtool-1.4 (and to a
5206 lesser extent libtool-1.3), the .la files will also store
5207 information about inter-library dependencies which cannot
5208 necessarily be derived after the .la file is deleted.
5212 Packages that use libtool to create shared libraries should
5213 include the <em>.la</em> files in the <em>-dev</em>
5214 packages, with the exception that if the package relies on
5215 libtool's <em>libltdl</em> library, in which case the .la
5216 files must go in the run-time library package. This is a
5217 good idea in general, and especially for static linking
5222 You must make sure that you use only released versions of
5223 shared libraries to build your packages; otherwise other
5224 users will not be able to run your binaries
5225 properly. Producing source packages that depend on
5226 unreleased compilers is also usually a bad
5233 <heading>Shared libraries</heading>
5236 Packages involving shared libraries should be split up
5237 into several binary packages.</p>
5240 For a straightforward library which has a development
5241 environment and a runtime kit including just shared
5242 libraries you need to create two packages:
5243 <tt><var>libraryname</var><var>soname</var></tt>
5244 (<var>soname</var> is the shared object name of the shared
5245 library--it's the thing that has to match exactly between
5246 building an executable and running it for the dynamic
5247 linker to be able run the program; usually the
5248 <var>soname</var> is the major number of the library) and
5249 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5252 If you prefer only to support one development version at a
5253 time you may name the development package
5254 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5255 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5256 ensure that the user only installs one development version
5257 at a time (after all, different development versions are
5258 likely to have the same header files in them, causing a
5259 filename clash if both are installed). Typically the
5260 development version should also have an exact version
5261 dependency on the runtime library, to make sure that
5262 compilation and linking happens correctly.</p>
5265 Packages which use the shared library should have a
5266 dependency on the name of the shared library package,
5267 <tt><var>libraryname</var><var>soname</var></tt>. When
5268 the <var>soname</var> changes you can have both versions
5269 of the library installed while moving from the old library
5273 If your package has some run-time support programs which
5274 use the shared library you must not put them in
5275 the shared library package. If you do that then you won't
5276 be able to install several versions of the shared library
5277 without getting filename clashes. Instead, either create
5278 a third package for the runtime binaries (this package
5279 might typically be named
5280 <tt><var>libraryname</var>-runtime</tt>--note the absence
5281 of the <var>soname</var> in the package name) or if the
5282 development package is small include them in there.</p>
5285 If you have several shared libraries built from the same
5286 source tree you may lump them all together into a single
5287 shared library package, provided that you change all their
5288 <var>soname</var>s at once (so that you don't get filename
5289 clashes if you try to install different versions of the
5290 combined shared libraries package).</p>
5293 You should follow the directions in the <em>Debian Packaging
5294 Manual</em> (or other documentation of the Debian
5295 packaging tools) for putting the shared library in its
5296 package, and you must include a <tt>shlibs</tt> control area
5297 file with details of the dependencies for packages which use
5301 Shared libraries should not be installed
5302 executable, since <prgn>ld.so</prgn> does not require this
5303 and trying to execute a shared library results in a core
5308 <heading>Scripts</heading>
5311 All command scripts, including the package maintainer
5312 scripts inside the package and used by <prgn>dpkg</prgn>,
5313 should have a <tt>#!</tt> line naming the shell to be used
5314 to interpret them.</p>
5317 In the case of Perl scripts this should be
5318 <tt>#!/usr/bin/perl</tt>.</p>
5321 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5322 should almost certainly start with <tt>set -e</tt> so that
5323 errors are detected. Every script should use
5324 <tt>set -e</tt> or check the exit status of <em>every</em>
5328 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5329 symbolic link to any POSIX compatible shell, if <tt>echo
5330 -n</tt> does not generate a newline.
5333 Debian policy specifies POSIX behavior for /bin/sh, but
5334 echo -n has widespread use in the Linux community
5335 (including especially debian policy, the linux kernel
5336 source, many debian scripts, etc.). This echo -n
5337 mechanism is valid but not required under POSIX, hence
5338 this explicit addition. Also, rumour has it that this
5339 shall be mandated under the LSB anyway.
5343 specifying `<tt>/bin/sh</tt>' as interpreter should only
5344 use POSIX features. If a script requires non-POSIX
5345 features from the shell interpreter, the appropriate shell
5346 must be specified in the first line of the script (e.g.,
5347 `<tt>#!/bin/bash</tt>') and the package must depend on the
5348 package providing the shell (unless the shell package is
5349 marked `Essential', e.g., in the case of
5354 You may wish to restrict your script to POSIX features when possible so
5355 that it may use <tt>/bin/sh</tt> as its interpreter. If
5356 your script works with <prgn>ash</prgn>, it's probably
5357 POSIX compliant, but if you are in doubt, use
5358 <tt>/bin/bash</tt>.</p>
5361 Perl scripts should check for errors when making any
5362 system calls, including <tt>open</tt>, <tt>print</tt>,
5363 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5366 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5367 as scripting languages. See <em>Csh Programming
5368 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5369 FAQs. It can be found on
5370 <url id="http://language.perl.com/versus/csh.whynot">, or
5371 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5372 or even on <ftpsite>ftp.cpan.org</ftpsite>
5373 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5374 If an upstream package comes with <prgn>csh</prgn> scripts
5375 then you must make sure that they start with
5376 <tt>#!/bin/csh</tt> and make your package depend on the
5377 <prgn>c-shell</prgn> virtual package.</p>
5380 Any scripts which create files in world-writeable
5381 directories (e.g., in <tt>/tmp</tt>) must use a
5382 mechanism which will fail if a file with the same name
5386 The Debian base distribution provides the
5387 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5388 for use by scripts for this purpose.</p></sect>
5392 <heading>Symbolic links</heading>
5395 In general, symbolic links within a top-level directory
5396 should be relative, and symbolic links pointing from one
5397 top-level directory into another should be absolute. (A
5398 top-level directory is a sub-directory of the root
5402 In addition, symbolic links should be specified as short
5403 as possible, i.e., link targets like `foo/../bar' are
5407 Note that when creating a relative link using
5408 <prgn>ln</prgn> it is not necessary for the target of the
5409 link to exist relative to the working directory you're
5410 running <prgn>ln</prgn> from; nor is it necessary to
5411 change directory to the directory where the link is to be
5412 made. Simply include the string that should appear as the
5413 target of the link (this will be a pathname relative to
5414 the directory in which the link resides) as the first
5415 argument to <prgn>ln</prgn>.</p>
5418 For example, in your <prgn>Makefile</prgn> or
5419 <tt>debian/rules</tt>, do things like:
5421 ln -fs gcc $(prefix)/bin/cc
5422 ln -fs gcc debian/tmp/usr/bin/cc
5423 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5424 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5428 A symbolic link pointing to a compressed file should
5429 always have the same file extension as the referenced
5430 file. (For example, if a file `<tt>foo.gz</tt>' is
5431 referenced by a symbolic link, the filename of the link
5432 has to end with `<tt>.gz</tt>' too, as in
5433 `bar.gz.')</p></sect>
5437 <heading>Device files</heading>
5440 Packages must not include device files in the package file
5444 If a package needs any special device files that are not
5445 included in the base system, it must call
5446 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5447 after asking the user for permission to do so.</p>
5450 Packages must not remove any device files in the
5451 <tt>postrm</tt> or any other script. This is left to the
5452 system administrator.</p>
5455 Debian uses the serial devices
5456 <tt>/dev/ttyS*</tt>. Programs using the old
5457 <tt>/dev/cu*</tt> devices should be changed to use
5458 <tt>/dev/ttyS*</tt>.</p>
5461 <sect id="config files">
5462 <heading>Configuration files</heading>
5464 <heading>Definitions</heading>
5467 <tag>configuration file</tag>
5469 A file that affects the operation of program, or
5470 provides site- or host-specific information, or
5471 otherwise customizes the behavior of program.
5472 Typically, configuration files are intended to be
5473 modified by the system administrator (if needed or
5474 desired) to conform to local policy or provide more
5475 useful site-specific behavior.</p>
5478 <tag><tt>conffile</tt></tag>
5480 A file listed in a package's <tt>conffiles</tt>
5481 file, and is treated specially by <prgn>dpkg</prgn>
5482 (see the <em>Debian Packaging Manual</em>).</p>
5488 The distinction between these two is important; they are
5489 not interchangeable concepts. Almost all
5490 <tt>conffiles</tt> are configuration files, but many
5491 configuration files are not <tt>conffiles</tt>.</p>
5494 Note that a script that embeds configuration information
5495 (such as most of the files in <tt>/etc/init.d</tt> and
5496 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5497 configuration file and should be treated as such.</p>
5501 <heading>Location</heading>
5503 Any configuration files created or used by your package
5504 must reside in <tt>/etc</tt>. If there are several you
5505 should consider creating a subdirectory of <tt>/etc</tt>
5506 named after your package.</p>
5509 If your package creates or uses configuration files
5510 outside of <tt>/etc</tt>, and it is not feasible to modify
5511 the package to use the <tt>/etc</tt>, you should still put
5512 the files in <tt>/etc</tt> and create symbolic links to
5513 those files from the location that the package
5518 <heading>Behavior</heading>
5520 Configuration file handling must conform to the following
5524 <p>local changes must be preserved during a package
5528 <p>configuration files must be preserved when the
5529 package is removed, and only deleted when the
5530 package is purged.</p>
5535 The easy way to achieve this behavior is to make the
5536 configuration file a <tt>conffile</tt>. This is
5537 appropriate only if it is possible to distribute a default
5538 version that will work for most installations, although
5539 some system administrators may choose to modify it. This
5540 implies that the default version will be part of the
5541 package distribution, and must not be modified by the
5542 maintainer scripts during installation (or at any other
5547 In order to ensure that local changes are preserved
5548 correctly, no package may contain or make hard links to
5552 Rationale: There are two problems with hard links.
5553 The first is that some editors break the link while
5554 editing one of the files, so that the two files may
5555 unwittingly become different. The second is that
5556 <prgn>dpkg</prgn> might break the hard link while
5557 upgrading <tt>conffile</tt>s.
5563 The other way to do it is via the maintainer scripts.
5564 In this case, the configuration file must not be listed as
5565 a <tt>conffile</tt> and must not be part of the package
5566 distribution. If the existence of a file is required for
5567 the package to be sensibly configured it is the
5568 responsibility of the package maintainer to write scripts
5569 which correctly create, update, maintain and
5570 remove-on-purge the file. These scripts must be idempotent
5571 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5572 re-run them due to errors during installation or removal),
5573 must cope with all the variety of ways <prgn>dpkg</prgn>
5574 can call maintainer scripts, must not overwrite or
5575 otherwise mangle the user's configuration without asking,
5576 must not ask unnecessary questions (particularly during
5577 upgrades), and otherwise be good citizens.</p>
5580 The scripts are not required to configure every possible option for
5581 the package, but only those necessary to get the package
5582 running on a given system. Ideally the sysadmin should not
5583 have to do any configuration other than that done
5584 (semi-)automatically by the <tt>postinst</tt> script.</p>
5587 A common practice is to create a script called
5588 <tt><var>package</var>-configure</tt> and have the
5589 package's <tt>postinst</tt> call it if and only if the
5590 configuration file does not already exist. In certain
5591 cases it is useful for there to be an example or template
5592 file which the maintainer scripts use. Such files should
5593 be in <tt>/usr/share/<package></tt> or
5594 <tt>/usr/lib/<package></tt> with a symbolic link
5595 from <tt>/usr/share/doc/<package>/examples</tt>
5596 if they are examples, and should be
5597 perfectly ordinary <prgn>dpkg</prgn>-handled files
5598 (<em>not</em> <tt>conffiles</tt>).
5602 These two styles of configuration file handling must
5603 not be mixed, for that way lies madness:
5604 <prgn>dpkg</prgn> will ask about overwriting the file
5605 every time the package is upgraded.</p>
5610 <heading>Sharing configuration files</heading>
5612 Packages which specify the same file as
5613 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5618 The maintainer scripts must not alter the conffile of
5619 <em>any</em> package, including the one the scripts belong
5623 If two or more packages use the same configuration file
5624 and it is reasonable for both to be installed at the same
5625 time, one of these packages must be defined as
5626 <em>owner</em> of the configuration file, i.e., it will be
5627 the package to list that distributes the file and lists it
5628 as a <tt>conffile</tt>. Other packages that use the
5629 configuration file must depend on the owning package if
5630 they require the configuration file to operate. If the
5631 other package will use the configuration file if present,
5632 but is capable of operating without it, no dependency need
5636 If it is desirable for two or more related packages to
5637 share a configuration file <em>and</em> for all of the
5638 related packages to be able to modify that configuration
5639 file, then the following should be done:
5643 have one of the related packages (the "core"
5644 package) manage the configuration file with
5645 maintainer scripts as described in the previous
5649 the core package should also provide a program that
5650 the other packages may use to modify the
5651 configuration file.</p>
5655 the related packages must use the provided program
5656 to make any modifications to the configuration file.
5657 They should either depend on the core package to
5658 guarantee that the configuration modifier program is
5659 available or accept gracefully that they cannot
5660 modify the configuration file if it is not.</p>
5665 Sometimes it's appropriate to create a new package which
5666 provides the basic infrastructure for the other packages
5667 and which manages the shared configuration files. (Check
5668 out the <tt>sgml-base</tt> package as an example.)</p>
5672 <heading>User configuration files ("dotfiles")</heading>
5675 Files in <tt>/etc/skel</tt> will automatically be copied
5676 into new user accounts by <prgn>adduser</prgn>. They
5677 should not be referenced there by any program.</p>
5680 Therefore, if a program needs a dotfile to exist in
5681 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5682 should be installed in <tt>/etc/skel</tt> (and listed in
5683 conffiles, if it is not generated and modified dynamically
5684 by the package's installation scripts).</p>
5687 However, programs that require dotfiles in order to
5688 operate sensibly (dotfiles that they do not create
5689 themselves automatically, that is) are a bad thing, and
5690 programs should be configured by the Debian default
5691 installation as close to normal as possible.</p>
5694 Therefore, if a program in a Debian package needs to be
5695 configured in some way in order to operate sensibly that
5696 configuration should be done in a site-wide global
5697 configuration file elsewhere in <tt>/etc</tt>. Only if the
5698 program doesn't support a site-wide default configuration
5699 and the package maintainer doesn't have time to add it
5700 may a default per-user file be placed in
5701 <tt>/etc/skel</tt>.</p>
5704 <tt>/etc/skel</tt> should be as empty as we can make it.
5705 This is particularly true because there is no easy
5706 mechanism for ensuring that the appropriate dotfiles are
5707 copied into the accounts of existing users when a package
5713 <heading>Log files</heading>
5715 The traditional approach to log files has been to set up ad
5716 hoc log rotation schemes using simple shell scripts and
5717 cron. While this approach is highly customizable, it
5718 requires quite a lot of sysadmin work. Even though the
5719 original Debian system helped a little by automatically
5720 installing a system which can be used as a template, this
5721 was deemed not enough.
5725 A better scheme is to use logrotate, a GPL'd program
5726 developed by Red Hat, which centralizes log management. It
5727 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5728 and a directory where packages can drop logrotation info
5729 (<tt>/etc/logrotate.d</tt>).
5733 Log files should usually be named
5734 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5735 log files, or need a separate directory for permissions
5736 reasons (<tt>/var/log</tt> is writable only by
5737 <tt>root</tt>), you should usually create a directory named
5738 <tt>/var/log/<var>package</var></tt>.</p>
5741 Log files must be rotated occasionally so
5742 that they don't grow indefinitely; the best way to do this
5743 is to drop a script into the directory
5744 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5745 logrotate. Here is a good example for a logrotate config
5746 file (for more information see <manref name="logrotate"
5754 /etc/init.d/foo force-reload
5758 Which rotates all files under `/var/log/foo', saves 12
5759 compressed generations, and sends a HUP signal at the end of
5765 Log files should be removed when the package is
5766 purged (but not when it is only removed), by checking the
5767 argument to the <tt>postrm</tt> script (see the <em>Debian
5768 Packaging Manual</em> for details).</p>
5773 <heading>Permissions and owners</heading>
5776 The rules in this section are guidelines for general use.
5777 If necessary you may deviate from the details below.
5778 However, if you do so you must make sure that what is done
5779 is secure and you should try to be as consistent as possible
5780 with the rest of the system. You should probably also
5781 discuss it on <prgn>debian-devel</prgn> first.</p>
5784 Files should be owned by <tt>root.root</tt>, and made
5785 writable only by the owner and universally readable (and
5786 executable, if appropriate).</p>
5789 Directories should be mode 755 or (for group-writability)
5790 mode 2775. The ownership of the directory should be
5791 consistent with its mode--if a directory is mode 2775, it
5792 should be owned by the group that needs write access to
5796 Setuid and setgid executables should be mode 4755 or 2755
5797 respectively, and owned by the appropriate user or group.
5798 They should not be made unreadable (modes like 4711 or
5799 2711 or even 4111); doing so achieves no extra security,
5800 because anyone can find the binary in the freely available
5801 Debian package--it is merely inconvenient. For the same
5802 reason you should not restrict read or execute permissions
5803 on non-set-id executables.</p>
5806 Some setuid programs need to be restricted to particular
5807 sets of users, using file permissions. In this case they
5808 should be owned by the uid to which they are set-id, and
5809 by the group which should be allowed to execute them.
5810 They should have mode 4754; there is no point in making
5811 them unreadable to those users who must not be allowed to
5815 You must not arrange that the system administrator can only
5816 reconfigure the package to correspond to their local
5817 security policy by changing the permissions on a binary.
5818 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5819 to conffiles and other similar objects) have their
5820 permissions reset to the distributed permissions when the
5821 package is reinstalled. Instead you should consider (for
5822 example) creating a group for people allowed to use the
5823 program(s) and making any setuid executables executable
5824 only by that group.</p>
5827 If you need to create a new user or group for your package
5828 there are two possibilities. Firstly, you may need to
5829 make some files in the binary package be owned by this
5830 user or group, or you may need to compile the user or
5831 group id (rather than just the name) into the binary
5832 (though this latter should be avoided if possible, as in
5833 this case you need a statically allocated id).</p>
5836 If you need a statically allocated id, you must ask for a
5837 user or group id from the base system
5838 maintainer, and must not release the package until you
5839 have been allocated one. Once you have been allocated one
5840 you must make the package depend on a version of the base
5841 system with the id present in <tt>/etc/passwd</tt> or
5842 <tt>/etc/group</tt>, or alternatively arrange for your
5843 package to create the user or group itself with the
5844 correct id (using <tt>adduser</tt>) in its pre- or
5845 post-installation script (the latter is to be preferred if
5846 it is possible).</p>
5849 On the other hand, the program might be able to determine the
5850 uid or gid from the group name at runtime, so that a
5851 dynamic id can be used. In this case you should choose an
5852 appropriate user or group name, discussing this on
5853 <prgn>debian-devel</prgn> and checking with the base
5854 system maintainer that it is unique and that they do not
5855 wish you to use a statically allocated id instead. When
5856 this has been checked you must arrange for your package to
5857 create the user or group if necessary using
5858 <prgn>adduser</prgn> in the pre- or post-installation
5859 script (again, the latter is to be preferred if it is
5863 Note that changing the numeric value of an id associated with a name
5864 is very difficult, and involves searching the file system for all
5865 appropriate files. You need to think carefully whether a static or
5866 dynamic id is required, since changing your mind later will cause
5871 <chapt id="customized-programs">
5872 <heading>Customized programs</heading>
5874 <sect id="arch-spec">
5875 <heading>Architecture specification strings</heading>
5878 If a program needs to specify an <em>architecture specification
5879 string</em> in some place, the following format should be used:
5881 <arch>-<os>
5883 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5884 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5885 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5886 operating system.</p>
5888 Note, that we don't want to use `<arch>-debian-linux'
5889 to apply to the rule `architecture-vendor-os' since this
5890 would make our programs incompatible to other Linux
5891 distributions. Also note, that we don't use
5892 `<arch>-unknown-linux', since the `unknown' does not
5893 look very good.</p></sect>
5897 <heading>Daemons</heading>
5900 The configuration files <tt>/etc/services</tt>,
5901 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5902 by the <prgn>netbase</prgn> package and may not be modified
5903 by other packages.</p>
5906 If a package requires a new entry in one of these files, the
5907 maintainer should get in contact with the
5908 <prgn>netbase</prgn> maintainer, who will add the entries
5909 and release a new version of the <prgn>netbase</prgn>
5913 The configuration file <tt>/etc/inetd.conf</tt> must not be
5914 modified by the package's scripts except via the
5915 <prgn>update-inetd</prgn> script or the
5916 <prgn>DebianNet.pm</prgn> Perl module.</p>
5919 If a package wants to install an example entry into
5920 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5921 exactly one hash character (<tt>#</tt>). Such lines are
5922 treated as `commented out by user' by the
5923 <prgn>update-inetd</prgn> script and are not changed or
5924 activated during a package updates.</p></sect>
5928 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5931 Some programs need to create pseudo-ttys. This should be done
5932 using Unix98 ptys if the C library supports it. The resulting
5933 program must not be installed setuid root, unless that
5934 is required for other functionality.
5938 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5939 <tt>/var/log/lastlog</tt> must be installed writeable by
5940 group utmp. Programs who need to modify those files must
5941 be installed setgid utmp.
5946 <heading>Editors and pagers</heading>
5949 Some programs have the ability to launch an editor or pager
5950 program to edit or display a text document. Since there are
5951 lots of different editors and pagers available in the Debian
5952 distribution, the system administrator and each user should
5953 have the possibility to choose his/her preferred editor and
5957 In addition, every program should choose a good default
5958 editor/pager if none is selected by the user or system
5962 Thus, every program that launches an editor or pager must
5963 use the EDITOR or PAGER environment variables to determine
5964 the editor/pager the user wants to get started. If these
5965 variables are not set, the programs <tt>/usr/bin/editor</tt>
5966 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5969 These two files are managed through `alternatives.' That is,
5970 every package providing an editor or pager must call the
5971 <prgn>update-alternatives</prgn> script to register these
5975 If it is very hard to adapt a program to make us of the
5976 EDITOR and PAGER variables, that program may be configured
5977 to use <tt>/usr/bin/sensible-editor</tt> and
5978 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5979 respectively. These are two scripts provided in the Debian
5980 base system that check the EDITOR and PAGER variables and
5981 launch the appropriate program or fall back to
5982 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5986 A program may also use the VISUAL environment variable to
5987 determine the user's choice of editor. If it exists, it
5988 should take precedence over EDITOR. This is in fact what
5989 <tt>/usr/bin/sensible-editor</tt> does.</p>
5992 It is not required for a package to depend on
5993 `editor' and `pager', nor is it required for a package to
5994 provide such virtual packages.
5997 The Debian base system already provides an editor and
6006 <sect id="web-appl">
6007 <heading>Web servers and applications</heading>
6010 This section describes the locations and URLs that should
6011 be used by all web servers and web application in the Debian
6017 <p>Cgi-bin executable files are installed in the
6020 /usr/lib/cgi-bin/<cgi-bin-name>
6022 and should be referred to as
6024 http://localhost/cgi-bin/<cgi-bin-name>
6025 </example></p></item>
6028 <item><p>Access to html documents</p>
6031 Html documents for a package are stored in
6032 <tt>/usr/share/doc/<var>package</var></tt> but should
6033 be accessed via symlinks as
6034 <tt>/usr/doc/<var>package</var></tt><footnote> for
6035 backward compatibility, see <ref id="usrdoc"></footnote>
6036 and can be referred to as
6038 http://localhost/doc/<package>/<filename>
6039 </example></p></item>
6042 <item><p>Web Document Root</p>
6045 Web Applications should try to avoid storing files in
6046 the Web Document Root. Instead they should use the
6047 /usr/share/doc/<package> directory for documents and
6048 register the Web Application via the menu package. If
6049 access to the web-root is unavoidable then use
6053 as the Document Root. This might be just a
6054 symbolic link to the location where the sysadmin has
6055 put the real document root.</p>
6058 </enumlist></p></sect>
6061 <sect id="mail-transport-agents">
6062 <heading>Mail transport, delivery and user agents</heading>
6065 Debian packages which process electronic mail, whether
6066 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6067 must make sure that they are compatible with the
6068 configuration decisions below. Failure to do this may
6069 result in lost mail, broken <tt>From:</tt> lines, and other
6070 serious brain damage!</p>
6073 The mail spool is <tt>/var/mail</tt> and the interface
6074 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6075 per the FHS). On older systems, the mail spool may be
6076 physically located in /var/spool/mail, but all access to the
6077 mail spool should be via the /var/mail symlink. The mail
6078 spool is part of the base system and not part of the MTA
6083 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6084 programs (like IMAP daemons) must lock the mailbox in an
6085 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6086 be combined with dot locking. To avoid deadlocks, a
6087 program should use <tt>fcntl()</tt> first and dot locking
6088 after this or alternatively implement the two locking
6089 methods in a non blocking way<footnote>
6091 If it is not possible to establish both locks, the
6092 system shouldn't wait for the second lock to be
6093 established, but remove the first lock, wait a (random)
6094 time, and start over locking again.</p>
6095 </footnote>. Using the functions <tt>maillock</tt> and
6096 <tt>mailunlock</tt> provided by the
6097 <tt>liblockfile*</tt><footnote>
6099 <tt>liblockfile</tt> version >>1.01</p>
6100 </footnote> packages is the recommended way to realize this.
6104 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6105 unless the user has chosen otherwise. A MUA may remove a
6106 mailbox (unless it has nonstandard permissions) in which
6107 case the MTA or another MUA must recreate it if needed.
6108 Mailboxes must be writable by group mail.</p>
6111 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6112 be setgid mail to do the locking mentioned above (and
6113 must obviously avoid accessing other users' mailboxes
6114 using this privilege).</p>
6117 <tt>/etc/aliases</tt> is the source file for the system mail
6118 aliases (e.g., postmaster, usenet, etc.)--it is the one
6119 which the sysadmin and <tt>postinst</tt> scripts may edit.
6120 After <tt>/etc/aliases</tt> is edited the program or human
6121 editing it must call <prgn>newaliases</prgn>. All MTA
6122 packages must come with a <prgn>newaliases</prgn> program,
6123 even if it does nothing, but older MTA packages do not do
6124 this so programs should not fail if <prgn>newaliases</prgn>
6125 cannot be found.</p>
6128 The convention of writing <tt>forward to
6129 <var>address</var></tt> in the mailbox itself is not
6130 supported. Use a <tt>.forward</tt> file instead.</p>
6133 The <prgn>rmail</prgn> program used by UUCP
6134 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6135 Likewise, <prgn>rsmtp</prgn>, for receiving
6136 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6140 If you need to know what name to use (for example) on
6141 outgoing news and mail messages which are generated locally,
6142 you should use the file <tt>/etc/mailname</tt>. It will
6143 contain the portion after the username and <tt>@</tt> (at)
6144 sign for email addresses of users on the machine (followed
6148 A package should check for the existence of this file. If
6149 it exists it should use it without comment. (An MTA's
6150 prompting configuration script may wish to prompt the user
6151 even if it finds this file exists.) If it does not exist it
6152 should prompt the user for the value and store it in
6153 <tt>/etc/mailname</tt> as well as using it in the package's
6154 configuration. The prompt should make it clear that the
6155 name will not just be used by that package. For example, in
6156 this situation the INN package says:
6158 Please enter the `mail name' of your system. This is the
6159 hostname portion of the address to be shown on outgoing
6160 news and mail messages. The default is
6161 <var>syshostname</var>, your system's host name. Mail
6162 name [`<var>syshostname</var>']:
6164 where <var>syshostname</var> is the output of <tt>hostname
6165 --fqdn</tt>.</p></sect>
6169 <heading>News system configuration</heading>
6172 All the configuration files related to the NNTP (news)
6173 servers and clients should be located under
6174 <tt>/etc/news</tt>.</p>
6177 There are some configuration issues that apply to a number
6178 of news clients and server packages on the machine. These
6182 <tag>/etc/news/organization</tag>
6183 <item><p>A string which should appear as the
6184 organization header for all messages posted
6185 by NNTP clients on the machine</p></item>
6187 <tag>/etc/news/server</tag>
6188 <item><p>Contains the FQDN of the upstream NNTP
6189 server, or localhost if the local machine is
6190 an NNTP server.</p></item>
6193 Other global files may be added as required for cross-package news
6194 configuration.</p></sect>
6198 <heading>Programs for the X Window System</heading>
6201 <em>Programs that may be configured with support for the X Window
6202 System</em> must be configured to do so and must declare any
6203 package dependencies necessary to satisfy their runtime
6204 requirements when using the X Window System, unless the package
6205 in question is of standard or higher priority, in which case
6206 X-specific binaries may be split into a separate package, or
6207 alternative versions of the package with X support may be
6213 <em>Packages which provide an X server</em> that, directly or
6214 indirectly, communicates with real input and display hardware
6215 should declare in their control data that they provide the
6216 virtual package <tt>xserver</tt>.
6219 This implements current practice, and provides an actual
6220 policy for usage of the "xserver" virtual package which
6221 appears in the virtual packages list. In a nutshell, X
6222 servers that interface directly with the display and input
6223 hardware or via another subsystem (e.g., GGI) should provide
6224 xserver. Things like Xvfb, Xnest, and Xprt should not.
6230 <em>Packages that provide a terminal emulator</em> for the X
6231 Window System which support a terminal type with a terminfo
6232 description provided in the <tt>ncurses-base</tt> package
6233 should declare in their control data that they provide the
6234 virtual package <tt>x-terminal-emulator</tt>. They should
6235 also register themselves as an alternative for
6236 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6241 <em>Packages that provide window managers</em> should declare in
6242 their control data that they provide the virtual package
6243 <tt>x-window-manager</tt>. They should also register themselves as an
6244 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6245 calculated as follows:
6247 <item>Start with a priority of 20.</item>
6248 <item>If the window manager supports the Debian menu system,
6249 add 20 points if this support is available in the
6250 package's default configuration (i.e., no
6251 configuration files belonging to the system or user
6252 have to be edited to activate the feature); if
6253 configuration files must be modified, add only 10
6255 <item>If the window manager permits the X session to be
6256 restarted using a <em>different</em> window manager
6257 (without killing the X server) in its default
6258 configuration, add 10 points; otherwise add
6264 <em>Packages that provide fonts for the X Window System</em>
6265 must do a number of things to ensure that they are both
6266 available without modification of the X or font server
6267 configuration, and that they do not corrupt files used by
6268 other font packages to register information about themselves.
6271 Fonts of any type supported by the X Window System
6272 should be be in a separate binary package from any
6273 executables, libraries, or documentation (except that
6274 specific to the fonts shipped); if a program or
6275 library is <em>unusable</em> without one or more
6276 specific fonts, the package containing the program or
6277 library should declare a dependency on the package(s)
6278 containing the font(s) it requires.
6281 BDF fonts should be converted to PCF fonts with the
6282 <tt>bdftopcf</tt> utility (available in the
6283 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6284 placed in a directory that corresponds to their
6288 100 dpi fonts should be placed in
6289 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6292 75 dpi fonts should be placed in
6293 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6296 Character-cell fonts, cursor fonts, and other
6297 low-resolution fonts should be placed in
6298 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6303 Speedo fonts should be placed in
6304 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6307 Type 1 fonts should be placed in
6308 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6309 metric files are available, they may be placed here as
6313 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6314 other than those listed above should be neither created nor
6315 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6316 excepted for historical reasons, but installation of files into
6317 these directories remains discouraged.)
6320 Font packages may, instead of placing files directly in
6321 the X font directories listed above, provide symbolic links in
6322 the font directory which point to the files' actual location
6323 in the filesystem. Such a location should comply with the
6327 Font packages should not contain both 75dpi and 100dpi
6328 versions of a font. If both are available, they should be
6329 provided in separate binary packages with "-75dpi" or "-100dpi"
6330 appended to the names of the packages containing the
6331 corresponding fonts.
6334 Fonts destined for the <tt>misc</tt> subdirectory should
6335 not be included in the same package as 75dpi or 100dpi fonts;
6336 instead, they should be provided in a separate package with
6337 "-misc" appended to its name.
6340 Font packages <em>must not</em> provide the files
6341 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6342 <tt>fonts.scale</tt> in a font directory.
6345 <tt>fonts.dir</tt> files must not be provided at
6349 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6350 files, if needed, should be provided in the
6352 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6353 where <em>fontdir</em> is the name of the
6355 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6356 package's corresponding fonts are stored (e.g.,
6357 <tt>75dpi</tt> or <tt>misc</tt>),
6358 <em>package</em> is the name of the package that
6359 provides these fonts, and <em>extension</em> is
6360 either <tt>scale</tt> or <tt>alias</tt>,
6361 whichever corresponds to the file
6367 Font packages must declare a dependency on
6368 <tt>xutils</tt> and, in the package
6369 post-installation and post-removal scripts, invoke the
6370 <tt>mkfontdir</tt> command on each directory into
6371 which they installed fonts.
6374 Font packages that provide one or more
6375 <tt>fonts.scale</tt> files as described above must declare a
6376 versioned dependency on <tt>xutils (>=
6377 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6378 directory into which they installed fonts
6379 <em>before</em> invoking <tt>mkfontdir</tt> on that
6380 directory. This invocation must occur in both the
6381 post-installation and post-removal scripts.
6384 Font packages that provide one or more
6385 <tt>fonts.alias</tt> files as described above must
6386 declare a versioned dependency on <tt>xutils
6387 (>= 4.0.2)</tt> and, in the package
6388 post-installation and post-removal scripts, invoke
6389 <tt>update-fonts-alias</tt> on each directory into
6390 which they installed fonts.
6393 Font packages must not provide alias names for the
6394 fonts they include which collide with alias names already in
6395 use by fonts already packaged.
6398 Font packages must not provide fonts with the same XLFD
6399 registry name as another font already packaged.
6405 <em>Application defaults</em> files must be installed in the
6406 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6407 localized subdirectory of <tt>/etc/X11/</tt> as described in
6408 the <em>X Toolkit Intrinsics - C Language Interface</em>
6409 manual is also permitted). They must be registered as
6410 <em>conffile</em>s or handled as configuration files. For
6411 programs that are not linked against the X Toolkit (Xt)
6412 library, customization of programs' X resources may also be
6413 supported with the provision of a file with the same name as
6414 that of the package placed in the
6415 <tt>/etc/X11/Xresources/</tt> directory, which must
6416 registered as a <em>conffile</em> or handled as a
6417 configuration file. <em>Important:</em> packages that
6418 install files into the <tt>/etc/X11/Xresources/</tt>
6419 directory <em>must</em> declare a conflict with <tt>xbase
6420 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6421 possible for the installing package to destroy a
6422 previously-existing <tt>/etc/X11/Xresources</tt> file which
6423 had been customized by the system administrator.
6427 <em>Packages using the X Window System should abide by the FHS
6428 standard whenever possible</em>; they should install binaries,
6429 libraries, manual pages, and other files in FHS-mandated
6430 locations wherever possible. This means that files must
6431 not be installed into <tt>/usr/X11R6/bin/</tt>,
6432 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6433 this is necessary for the package to operate properly.
6434 Configuration files for window managers and display managers
6435 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6436 corresponding to the package name due to these programs'
6437 tight integration with the mechanisms of the X Window
6438 System. Application-level programs should use the
6439 <tt>/etc/</tt> directory unless otherwise mandated by
6440 policy. The installation of files into subdirectories of
6441 <tt>/usr/X11R6/include/X11/</tt> and
6442 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6443 package maintainers should determine if subdirectories of
6444 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6445 instead (symlinks from the X11R6 directories to
6446 FHS-compliant locations is encouraged if the program is not
6447 easily configured to look elsewhere for its files).
6448 Packages must not provide -- or install files into -- the
6449 directories <tt>/usr/bin/X11/</tt>,
6450 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6451 Files within a package should, however, make reference to
6452 these directories, rather than their X11R6-named
6453 counterparts <tt>/usr/X11R6/bin/</tt>,
6454 <tt>/usr/X11R6/include/X11/</tt>, and
6455 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6456 referred to have not been moved to FHS-compliant locations.
6460 <em>Programs that require the non-DFSG-compliant OSF/Motif
6461 library</em> should be compiled against and tested with
6462 LessTif (a free re-implementation of Motif) instead. If the
6463 maintainer judges that the program or programs do not work
6464 sufficiently well with LessTif to be distributed and
6465 supported, but do so when compiled against Motif, then two
6466 versions of the package should be created; one linked
6467 statically against Motif and with <tt>-smotif</tt> appended
6468 to the package name, and one linked dynamically against
6469 Motif and with <tt>-dmotif</tt> appended to the package
6470 name. Both Motif-linked versions are dependent upon
6471 non-DFSG-compliant software and thus cannot be uploaded to
6472 the main distribution; if the software is itself
6473 DFSG-compliant it may be uploaded to the contrib
6474 distribution. While known existing versions of OSF/Motif
6475 permit unlimited redistribution of binaries linked against
6476 the library (whether statically or dynamically), it is the
6477 package maintainer's responsibility to determine whether
6478 this is permitted by the license of the copy of OSF/Motif in
6479 his or her possession.
6484 <heading>Perl programs and modules</heading>
6486 Perl programs and modules should follow the current Perl
6487 policy as defined in the file found on
6488 <ftpsite>ftp.debian.org</ftpsite> in
6489 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
6490 or your local mirror. In addition, it is included in the
6491 <tt>debian-policy</tt> package.
6496 <heading>Emacs lisp programs</heading>
6499 Please refer to the `Debian Emacs Policy' (documented in
6500 <tt>debian-emacs-policy.gz</tt> of the
6501 <prgn>emacsen-common</prgn> package) for details of how to
6502 package emacs lisp programs.</p></sect>
6506 <heading>Games</heading>
6509 The permissions on /var/games are 755
6510 <tt>root.root</tt>.</p>
6513 Each game decides on its own security policy.</p>
6516 Games which require protected, privileged access to
6517 high-score files, savegames, etc., may be made
6518 set-<em>group</em>-id (mode 2755) and owned by
6519 <tt>root.games</tt>, and use files and directories with
6520 appropriate permissions (770 <tt>root.games</tt>, for
6521 example). They must not be made
6522 set-<em>user</em>-id, as this causes security problems. (If
6523 an attacker can subvert any set-user-id game they can
6524 overwrite the executable of any other, causing other players
6525 of these games to run a Trojan horse program. With a
6526 set-group-id game the attacker only gets access to less
6527 important game data, and if they can get at the other
6528 players' accounts at all it will take considerably more
6532 Some packages, for example some fortune cookie programs, are
6533 configured by the upstream authors to install with their
6534 data files or other static information made unreadable so
6535 that they can only be accessed through set-id programs
6536 provided. You should not do this in a Debian package: anyone can
6537 download the <tt>.deb</tt> file and read the data from it,
6538 so there is no point making the files unreadable. Not
6539 making the files unreadable also means that you don't have
6540 to make so many programs set-id, which reduces the risk of a
6544 As described in the FHS, binaries of games should be
6545 installed in the directory <tt>/usr/games</tt>. This also
6546 applies to games that use the X Window System. Manual pages
6547 for games (X and non-X games) should be installed in
6548 <tt>/usr/share/man/man6</tt>.</p>
6552 <chapt><heading>Documentation</heading>
6556 <heading>Manual pages</heading>
6559 You should install manual pages in <prgn>nroff</prgn> source
6560 form, in appropriate places under <tt>/usr/share/man</tt>. You
6561 should only use sections 1 to 9 (see the FHS for more
6562 details). You must not install a preformatted `cat
6566 Each program, utility, and function should have an
6567 associated manpage included in the same package. It is
6568 suggested that all configuration files also have a manual
6569 page included as well.
6573 If no manual page is available for a particular program,
6574 utility, function or configuration file and this is reported as a bug on
6575 debian-bugs, a symbolic link from the requested manual page
6576 to the <manref name="undocumented" section="7"> manual page
6577 may be provided. This symbolic link can be created from
6578 <tt>debian/rules</tt> like this:
6580 ln -s ../man7/undocumented.7.gz \
6581 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6583 This manpage claims that the lack of a manpage has been
6584 reported as a bug, so you may only do this if it really has
6585 (you can report it yourself, if you like). Do not close the
6586 bug report until a proper manpage is available.</p>
6589 You may forward a complaint about a missing manpage to the
6590 upstream authors, and mark the bug as forwarded in the
6591 Debian bug tracking system. Even though the GNU Project do
6592 not in general consider the lack of a manpage to be a bug,
6593 we do--if they tell you that they don't consider it a bug
6594 you should leave the bug in our bug tracking system open
6598 Manual pages should be installed compressed using <tt>gzip
6602 If one manpage needs to be accessible via several names it
6603 is better to use a symbolic link than the <tt>.so</tt>
6604 feature, but there is no need to fiddle with the relevant
6605 parts of the upstream source to change from <tt>.so</tt> to
6606 symlinks--don't do it unless it's easy. You should not create hard
6607 links in the manual page directories, nor put
6608 absolute filenames in <tt>.so</tt> directives. The filename
6609 in a <tt>.so</tt> in a manpage should be relative to the
6610 base of the manpage tree (usually
6611 <tt>/usr/share/man</tt>).</p></sect>
6615 <heading>Info documents</heading>
6618 Info documents should be installed in <tt>/usr/share/info</tt>.
6619 They should be compressed with <tt>gzip -9</tt>.</p>
6622 Your package should call <prgn>install-info</prgn> to update the Info
6624 file, in its post-installation script:
6626 install-info --quiet --section Development Development \
6627 /usr/share/info/foobar.info
6631 It is a good idea to specify a section for the location of
6632 your program; this is done with the <tt>--section</tt>
6633 switch. To determine which section to use, you should look
6634 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6635 relevant (or create a new section if none of the current
6636 sections are relevant). Note that the <tt>--section</tt>
6637 flag takes two arguments; the first is a regular expression
6638 to match (case-insensitively) against an existing section,
6639 the second is used when creating a new one.</p>
6642 You should remove the entries in the pre-removal script:
6644 install-info --quiet --remove /usr/share/info/foobar.info
6648 If <prgn>install-info</prgn> cannot find a description entry
6649 in the Info file you must supply one. See <manref
6650 name="install-info" section="8"> for details.</p>
6654 <heading>Additional documentation</heading>
6657 Any additional documentation that comes with the package may
6658 be installed at the discretion of the package maintainer.
6659 Text documentation should be installed in a directory
6660 <tt>/usr/share/doc/<var>package</var></tt>, where
6661 <var>package</var> is the name of the package, and
6662 compressed with <tt>gzip -9</tt> unless it is small.</p>
6665 If a package comes with large amounts of documentation which
6666 many users of the package will not require you should create
6667 a separate binary package to contain it, so that it does not
6668 take up disk space on the machines of users who do not need
6669 or want it installed.</p>
6672 It is often a good idea to put text information files
6673 (<tt>README</tt>s, changelogs, and so forth) that come with
6674 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6675 in the binary package. However, you don't need to install
6676 the instructions for building and installing the package, of
6680 Files in <tt>/usr/share/doc</tt> should not be referenced by
6681 any program, and the system administrator should be able to
6682 delete them without causing any programs to break. Any files
6683 that are referenced by programs but are also useful as
6684 standalone documentation should be installed under
6685 <tt>/usr/share/<package>/</tt> and symlinked in
6686 <tt>/usr/share/doc/<package>/</tt>.
6692 <heading>Accessing the documentation</heading>
6695 Former Debian releases placed all additional documentation
6696 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6698 <tt>/usr/share/doc/<var>package</var></tt>, each package
6699 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6700 that points to the new location of its documentation in
6701 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6702 symlinks will be removed in the future, but they have to be
6703 there for compatibility reasons until all packages have
6704 moved and the policy is changed accordingly.</footnote>.
6705 The symlink must be created when the package is installed;
6706 it cannot be contained in the package itself due to problems
6707 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6708 this is to put the following in the package's
6709 <prgn>postinst</prgn>:
6711 if [ "$1" = "configure" ]; then
6712 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6713 -a -d /usr/share/doc/#PACKAGE# ]; then
6714 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6718 And the following in the package's <prgn>prerm</prgn>:
6720 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6721 -a -L /usr/doc/#PACKAGE# ]; then
6722 rm -f /usr/doc/#PACKAGE#
6729 <heading>Preferred documentation formats</heading>
6732 The unification of Debian documentation is being carried out
6736 If your package comes with extensive documentation in a
6737 mark up format that can be converted to various other formats
6738 you should if possible ship HTML versions in a binary
6739 package, in the directory
6740 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6743 <p>The rationale: The important thing here is that HTML
6744 docs should be available in <em>some</em> package, not
6745 necessarily in the main binary package, though. </p>
6750 Other formats such as PostScript may be provided at your
6754 <sect id="copyrightfile">
6755 <heading>Copyright information</heading>
6758 Every package must be accompanied by a verbatim copy of its
6759 copyright and distribution license in the file
6760 /usr/share/doc/<package-name>/copyright. This file must
6761 neither be compressed nor be a symbolic link.</p>
6764 In addition, the copyright file must say where the upstream
6765 sources (if any) were obtained, and should explain briefly what
6766 modifications were made in the Debian version of the package
6767 compared to the upstream one. It should name the original
6768 authors of the package and the Debian maintainer(s) who were
6769 involved with its creation.</p>
6772 A copy of the file which will be installed in
6773 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6774 in <tt>debian/copyright</tt>.</p>
6778 /usr/share/doc/<package-name> may be a symbolic link to a
6779 directory in /usr/share/doc only if two packages both come from
6780 the same source and the first package has a "Depends"
6781 relationship on the second. These rules are important
6782 because copyrights must be extractable by mechanical
6786 Packages distributed under the UCB BSD license, the Artistic
6787 license, the GNU GPL, and the GNU LGPL should refer to the
6788 files /usr/share/common-licenses/BSD,
6789 /usr/share/common-licenses/Artistic,
6790 /usr/share/common-licenses/GPL, and
6791 /usr/share/common-licenses/LGPL.
6794 Why "licenses" and not "copyright"? Because
6795 <tt>/usr/doc/copyright</tt> used to contain all the
6796 copyright files, plus the four common licenses GPL,
6797 LGPL, Artistic and BSD. Now individual copyright files
6798 for packages are no longer in a common directory. Once
6799 <tt>/usr/doc/copyright</tt> is almost empty it makes
6800 sense to rename "copyright" to "licenses"
6803 Why "common-licenses" and not "licenses"? Because if I
6804 put just "licenses" I'm sure I will receive a bug report
6805 saying "license foo is not included in the licenses
6806 directory. They are not all the licenses, just a few
6807 common ones. I could use /usr/share/doc/common-licenses
6808 but I think this is too long, and, after all, the GPL
6809 does not "document" anything, it is merely a license.
6815 You should not use the copyright file as a general <tt>README</tt>
6816 file. If your package has such a file it should be
6817 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6818 <tt>README.Debian</tt> or some other appropriate place.</p>
6822 <heading>Examples</heading>
6825 Any examples (configurations, source files, whatever),
6826 should be installed in a directory
6827 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6828 files should not be referenced by any program--they're there
6829 for the benefit of the system administrator and users, as
6830 documentation only. Architecture-specific example files
6831 should be installed in a directory
6832 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6833 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6834 to files in it. Or the latter directory may be a symlink to
6838 <sect id="instchangelog">
6839 <heading>Changelog files</heading>
6842 Packages that are not Debian-native must contain a copy of
6843 <tt>debian/changelog</tt> file from the Debian source tree
6844 in <tt>/usr/share/doc/<var>package</var></tt> as
6845 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6846 available, it should be accessible as
6847 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6848 plain text. If the upstream changelog is distributed in
6849 HTML, it should be made available in that form as
6850 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6851 and the <tt>changelog.gz</tt> should be generated using, eg,
6852 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6853 do not already conform to this naming convention, then this
6854 may be achieved either by renaming the files, or adding a
6855 symbolic link, at the maintainer's discretion.
6858 Rationale: People should not have to look into two
6859 places for upstream changelogs merely because they are
6867 All these files should be installed compressed using <tt>gzip -9</tt>,
6868 as they will become large with time even if they start out
6873 If the package has only one changelog which is used both as
6874 the Debian changelog and the upstream one because there is
6875 no separate upstream maintainer then that changelog should
6876 usually be installed as
6877 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6878 there is a separate upstream maintainer, but no upstream
6879 changelog, then the Debian changelog should still be called
6880 <tt>changelog.Debian.gz</tt>.</p>