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8 Debian GNU/Linux Policy Manual.
9 Copyright (C)1996,1997,1998 Ian Jackson and Christian Schwarz;
10 released under the terms of the GNU
11 General Public License, version 2 or (at your option) any later.
12 Initial version 1996, Ian Jackson, ijackson@gnu.ai.mit.edu
13 Revised November 27, 1996, David A. Morris, bweaver@debian.org
14 New sections March 15, 1997, Christian Schwarz, schwarz@debian.org
15 Reworked/Restructured April-July 1997, Christian Schwarz, schwarz@debian.org
16 Maintainer since 1997, Christian Schwarz, schwarz@debian.org
17 Christoph Lameter contributed the "Web Standard"
18 The debian-policy mailing list has taken responsibility for the
19 contents of this document since September 1998, with the package
20 maintainers responsible for packaging administrivia only.
25 <title>Debian Policy Manual</title>
27 <name>Ian Jackson </name>
28 <email>ijackson@gnu.ai.mit.edu</email>
31 <name>Christian Schwarz</name>
32 <email>schwarz@debian.org</email>
35 <name>revised: David A. Morris</name>
36 <email>bweaver@debian.org</email>
39 <name>The Debian Policy mailing List</name>
40 <email>debian-policy@lists.debian.org</email>
42 <version>version &version;, &date;</version>
45 This manual describes the policy requirements for the Debian
46 GNU/Linux distribution. This includes the structure and
47 contents of the Debian archive and several design issues of the
48 operating system, as well as technical requirements that each
49 package must satisfy to be included in the distribution. The
50 policy package itself is maintained by a group of maintainers
51 that have no editorial powers. At the moment, the list of
55 <p>Julian Gilbey <email>jdg@debian.org</email></p>
58 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
66 Copyright ©1996,1997,1998 Ian Jackson
67 and Christian Schwarz.
70 This manual is free software; you may redistribute it and/or
71 modify it under the terms of the GNU General Public License
72 as published by the Free Software Foundation; either version
73 2, or (at your option) any later version.
77 This is distributed in the hope that it will be useful, but
78 <em>without any warranty</em>; without even the implied
79 warranty of merchantability or fitness for a particular
80 purpose. See the GNU General Public License for more
85 A copy of the GNU General Public License is available as
86 <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
87 distribution or on the World Wide Web at
88 <url id="http://www.gnu.org/copyleft/gpl.html"
89 name="The GNU General Public Licence">. You can also obtain it by writing to the
90 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
91 Boston, MA 02111-1307, USA.
99 <heading>About this manual</heading>
101 <heading>Scope</heading>
103 This manual describes the policy requirements for the Debian
104 GNU/Linux distribution. This includes the structure and
105 contents of the Debian archive and several design issues of the
106 operating system, as well as technical requirements that
107 each package must satisfy to be included in the
113 This manual also describes Debian policy as it relates to
114 creating Debian packages. It is not a tutorial on how to build
115 packages, nor is it exhaustive where it comes to describing
116 the behavior of the packaging system. Instead, this manual
117 attempts to define the interface to the package management
118 system that the developers have to be conversant with.
121 Informally, the criteria used for inclusion is that the
122 material meet one of the following requirements:
124 <tag>Standard interfaces</tag>
127 The material presented represents an interface to
128 the packaging system that is mandated for use, and
129 is used by, a significant number of packages, and
130 therefore should not be changed without peer
131 review. Package maintainers can then rely on this
132 interfaces not changing, and the package
133 management software authors need to ensure
134 compatibility with these interface
135 definitions. (Control file and and changelog file
136 formats are examples.)
139 <tag>Chosen Convention</tag>
142 If there are a number of technically viable choices
143 that can be made, but one needs to select one of
144 these options for inter-operability. The version
145 number format is one example.
149 Please note that these are not mutually exclusive;
150 selected conventions often become parts of standard
157 The footnotes present in this manual are
158 merely informative, and are not part of Debian policy itself.
163 In this manual, the words <em>must</em>, <em>should</em> and
164 <em>may</em>, and the adjectives <em>required</em>,
165 <em>recommended</em> and <em>optional</em>, are used to
166 distinguish the significance of the various guidelines in
167 this policy document. Packages that do not conform the the
168 guidelines denoted by <em>must</em> (or <em>required</em>)
169 will generally not be considered acceptable for the Debian
170 distribution. Non-conformance with guidelines denoted by
171 <em>should</em> (or <em>recommended</em>) will generally be
172 considered a bug, but will not necessarily render a package
173 unsuitable for distribution. Guidelines denoted by
174 <em>may</em> (or <em>optional</em>) are truly optional and
175 adherence is left to the maintainer's discretion.
178 These classifications are roughly equivalent to the bug
179 severities <em>serious</em> (for <em>must</em> or
180 <em>required</em> directive violations), <em>minor</em>,
181 <em>normal</em> or <em>important</em>
182 (for <em>should</em> or <em>recommended</em> directive
183 violations) and <em>wishlist</em> (for <em>optional</em>
185 <p>Compare RFC 2119. Note, however, that these words are
186 used in a different way in this document.</p>
190 Much of the information presented in this manual will be
191 useful even when building a package which is to be
192 distributed in some other way or is intended for local use
197 <heading>New versions of this document</heading>
199 The current version of this document is always accessible
200 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
202 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
203 (also available from the same directory are several other
204 formats: <tt>policy.html.tar.gz</tt>, <tt>policy.pdf.gz</tt>
205 and <tt>policy.ps.gz</tt>) or from the <url
206 id="http://www.debian.org/doc/debian-policy/" name="Debian
207 Policy Manual"> webpage.</p>
210 In addition, this manual is distributed via the Debian package
211 <tt>debian-policy</tt>.
215 The <tt>debian-policy</tt> package also includes the file
216 <tt>upgrading-checklist.txt</tt> which indicates policy
217 changes between versions of this document.
221 <heading>Feedback</heading>
224 As the Debian GNU/Linux system is continuously evolving this
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
239 <heading>The Debian Archive</heading>
241 The Debian GNU/Linux system is maintained and distributed as a
242 collection of <em>packages</em>. Since there are so many of
243 them (currently well over 6000), they are split into
244 <em>sections</em> and given <em>priorities</em> to simplify
245 the handling of them.
248 The effort of the Debian project is to build a free operating
249 system, but not every package we want to make accessible is
250 <em>free</em> in our sense (see the Debian Free Software
251 Guidelines, below), or may be imported/exported without
252 restrictions. Thus, the archive is split into the sections
253 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
254 <em>non-US/main</em>, <em>non-US/non-free</em>, and
255 <em>non-US/contrib</em>. The sections are explained in detail
260 The <em>main</em> and the <em>non-US/main</em> sections
261 together form the <em>Debian GNU/Linux distribution</em>.
265 Packages in the other sections are not considered to be part
266 of the Debian distribution, although we support their use and
267 provide infrastructure for them (such as our bug-tracking
268 system and mailing lists). This Debian Policy Manual applies
269 to these packages as well.</p>
271 <sect id="pkgcopyright">
272 <heading>Package copyright and sections</heading>
274 The aims of this section are:
276 <list compact="compact">
278 <p>to allow us to make as much software available as we
282 <p>to allow us to encourage everyone to write free
286 <p>to allow us to make it easy for people to produce
287 CD-ROMs of our system without violating any licenses,
288 import/export restrictions, or any other laws.</p>
293 <heading>The Debian Free Software Guidelines</heading>
295 The Debian Free Software Guidelines (DFSG) form our
296 definition of `free software'. These are:
298 <tag>Free Redistribution
302 The license of a Debian component may not restrict any
303 party from selling or giving away the software as a
304 component of an aggregate software distribution
305 containing programs from several different
306 sources. The license may not require a royalty or
307 other fee for such sale.
314 The program must include source code, and must allow
315 distribution in source code as well as compiled form.
322 The license must allow modifications and derived
323 works, and must allow them to be distributed under the
324 same terms as the license of the original software.
327 <tag>Integrity of The Author's Source Code
331 The license may restrict source-code from being
332 distributed in modified form <em>only</em> if the
333 license allows the distribution of ``patch files''
334 with the source code for the purpose of modifying the
335 program at build time. The license must explicitly
336 permit distribution of software built from modified
337 source code. The license may require derived works to
338 carry a different name or version number from the
339 original software. (This is a compromise. The Debian
340 Project encourages all authors to not restrict any
341 files, source or binary, from being modified.)
344 <tag>No Discrimination Against Persons or Groups
348 The license must not discriminate against any person
352 <tag>No Discrimination Against Fields of Endeavor
356 The license must not restrict anyone from making use
357 of the program in a specific field of endeavor. For
358 example, it may not restrict the program from being
359 used in a business, or from being used for genetic
363 <tag>Distribution of License
367 The rights attached to the program must apply to all
368 to whom the program is redistributed without the need
369 for execution of an additional license by those
373 <tag>License Must Not Be Specific to Debian
377 The rights attached to the program must not depend on
378 the program's being part of a Debian system. If the
379 program is extracted from Debian and used or
380 distributed without Debian but otherwise within the
381 terms of the program's license, all parties to whom
382 the program is redistributed must have the same
383 rights as those that are granted in conjunction with
387 <tag>License Must Not Contaminate Other Software
391 The license must not place restrictions on other
392 software that is distributed along with the licensed
393 software. For example, the license must not insist
394 that all other programs distributed on the same medium
395 must be free software.
398 <tag>Example Licenses
402 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
403 examples of licenses that we consider <em>free</em>.
410 <heading>The main section</heading>
412 Every package in <em>main</em> and <em>non-US/main</em>
413 must comply with the DFSG (Debian Free Software
417 In addition, the packages in <em>main</em>
418 <list compact="compact">
421 must not require a package outside of <em>main</em>
422 for compilation or execution (thus, the package must
423 not declare a "Depends", "Recommends", or
424 "Build-Depends" relationship on a non-<em>main</em>
430 must not be so buggy that we refuse to support them,
436 must meet all policy requirements presented in this
443 Similarly, the packages in <em>non-US/main</em>
444 <list compact="compact">
447 must not require a package outside of <em>main</em>
448 or <em>non-US/main</em> for compilation or
454 must not be so buggy that we refuse to support them,
459 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
469 Every package in <em>contrib</em> and
470 <em>non-US/contrib</em> must comply with the DFSG.
474 In addition, the packages in <em>contrib</em> and
475 <em>non-US/contrib</em>
476 <list compact="compact">
479 must not be so buggy that we refuse to support them,
485 must meet all policy requirements presented in this
493 Furthermore, packages in <em>contrib</em> must not require
494 a package in a <em>non-US</em> section for compilation or
499 Examples of packages which would be included in
500 <em>contrib</em> or <em>non-US/contrib</em> are:
501 <list compact="compact">
504 free packages which require <em>contrib</em>,
505 <em>non-free</em> packages or packages which are not
506 in our archive at all for compilation or execution,
512 wrapper packages or other sorts of free accessories for
520 <heading>The non-free section</heading>
522 Packages must be placed in <em>non-free</em> or
523 <em>non-US/non-free</em> if they are not compliant with
524 the DFSG or are encumbered by patents or other legal
525 issues that make their distribution problematic.
528 In addition, the packages in <em>non-free</em> and
529 <em>non-US/non-free</em>
530 <list compact="compact">
533 must not be so buggy that we refuse to support them,
539 must meet all policy requirements presented in this
540 manual that it is possible for them to meet.
543 It is possible that there are policy
544 requirements which the package is unable to
545 meet, for example, if the source is
546 unavailable. These situations will need to be
547 handled on a case-by-case basis.
557 <heading>The non-US sections</heading>
559 Some programs with cryptographic program code need to be
560 stored on the <em>non-US</em> server because of United
561 States export restrictions. Such programs must be
562 distributed in the appropriate <em>non-US</em> section,
563 either <em>non-US/main</em>, <em>non-US/contrib</em> or
564 <em>non-US/non-free</em>.
567 This applies only to packages which contain cryptographic
568 code. A package containing a program with an interface to
569 a cryptographic program or a program that's dynamically
570 linked against a cryptographic library should not be
571 distributed via the <em>non-US</em> server if it is
572 capable of running without the cryptographic library or
577 <heading>Further copyright considerations</heading>
579 Every package must be accompanied by a verbatim copy of
580 its copyright and distribution license in the file
581 <tt>/usr/share/doc/<em><package-name></em>/copyright</tt>
582 (see <ref id="copyrightfile"> for further details).
585 We reserve the right to restrict files from being included
586 anywhere in our archives if
587 <list compact="compact">
590 their use or distribution would break a law,
595 there is an ethical conflict in their distribution or
601 we would have to sign a license for them, or
606 their distribution would conflict with other project
614 Programs whose authors encourage the user to make
615 donations are fine for the main distribution, provided
616 that the authors do not claim that not donating is
617 immoral, unethical, illegal or something similar; in such
618 a case they must go in <em>non-free</em>.</p>
621 Packages whose copyright permission notices (or patent
622 problems) do not even allow redistribution of binaries
623 only, and where no special permission has been obtained,
624 must not be placed on the Debian FTP site and its mirrors
628 Note that under international copyright law (this applies
629 in the United States, too), <em>no</em> distribution or
630 modification of a work is allowed without an explicit
631 notice saying so. Therefore a program without a copyright
632 notice <em>is</em> copyrighted and you may not do anything
633 to it without risking being sued! Likewise if a program
634 has a copyright notice but no statement saying what is
635 permitted then nothing is permitted.</p>
638 Many authors are unaware of the problems that restrictive
639 copyrights (or lack of copyright notices) can cause for
640 the users of their supposedly-free software. It is often
641 worthwhile contacting such authors diplomatically to ask
642 them to modify their license terms. However, this can be a
643 politically difficult thing to do and you should ask for
644 advice on the <tt>debian-legal</tt> mailing list first, as
649 When in doubt about a copyright, send mail to
650 <email>debian-legal@lists.debian.org</email>. Be prepared
651 to provide us with the copyright statement. Software
652 covered by the GPL, public domain software and BSD-like
653 copyrights are safe; be wary of the phrases `commercial
654 use prohibited' and `distribution restricted'.
658 <heading>Subsections</heading>
661 The packages in the sections <em>main</em>,
662 <em>contrib</em> and <em>non-free</em> are grouped further
663 into <em>subsections</em> to simplify handling.
667 The section and subsection for each package should be
668 specified in the package's <tt>Section</tt> control
669 record. However, the maintainer of the Debian archive
670 may override this selection to ensure the consistency of
671 the Debian distribution. The <tt>Section</tt> field
672 should be of the form:
673 <list compact="compact">
676 <em>subsection</em> if the package is in the
677 <em>main</em> section,
682 <em>section/subsection</em> if the package is in
683 the <em>contrib</em> or <em>non-free</em> section,
689 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
690 <tt>non-US/non-free</tt> if the package is in
691 <em>non-US/main</em>, <em>non-US/contrib</em> or
692 <em>non-US/non-free</em> respectively.
699 The Debian archive maintainers provide the authoritative
700 list of subsections. At present, they are:
701 <em>admin</em>, <em>base</em>, <em>comm</em>,
702 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
703 <em>editors</em>, <em>electronics</em>, <em>games</em>,
704 <em>graphics</em>, <em>hamradio</em>,
705 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
706 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
707 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
708 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
709 <em>sound</em>, <em>tex</em>, <em>text</em>,
710 <em>utils</em>, <em>web</em>, <em>x11</em>.
714 <heading>Priorities</heading>
717 Each package should have a <em>priority</em> value, which is
718 included in the package's <em>control record</em>. This
719 information is used by the Debian package management tools
720 to separate high-priority packages from less-important
724 The following <em>priority levels</em> are recognised by the
725 Debian package management tools.
727 <tag><tt>required</tt></tag>
730 Packages which are necessary for the proper
731 functioning of the system. You must not remove these
732 packages or your system may become totally broken and
733 you may not even be able to use <prgn>dpkg</prgn> to
734 put things back. Systems with only the
735 <tt>required</tt> packages are probably unusable, but
736 they do have enough functionality to allow the
737 sysadmin to boot and install more software.</p>
739 <tag><tt>important</tt></tag>
742 Important programs, including those which one would
743 expect to find on any Unix-like system. If the
744 expectation is that an experienced Unix person who
745 found it missing would say `What on earth is going on,
746 where is <prgn>foo</prgn>?', it must be an
747 <tt>important</tt> package.
750 This is an important criterion because we are
751 trying to produce, amongst other things, a free
755 Other packages without which the system will not run
756 well or be usable must also have priority
757 <tt>important</tt>. This does
758 <em>not</em> include Emacs, the X Window System, TeX
759 or any other large applications. The
760 <tt>important</tt> packages are just a bare minimum of
761 commonly-expected and necessary tools.</p>
763 <tag><tt>standard</tt></tag>
766 These packages provide a reasonably small but not too
767 limited character-mode system. This is what will
768 install by default if the user doesn't select anything
769 else. It doesn't include many large applications, but
770 it does include Emacs (this is more of a piece of
771 infrastructure than an application) and a reasonable
772 subset of TeX and LaTeX.</p>
774 <tag><tt>optional</tt></tag>
777 (In a sense everything that isn't required is
778 optional, but that's not what is meant here.) This is
779 all the software that you might reasonably want to
780 install if you didn't know what it was and don't have
781 specialized requirements. This is a much larger system
782 and includes the X Window System, a full TeX
783 distribution, and many applications. Note that
784 optional packages should not conflict with each other.
787 <tag><tt>extra</tt></tag>
790 This contains all packages that conflict with others
791 with required, important, standard or optional
792 priorities, or are only likely to be useful if you
793 already know what they are or have specialised
800 Packages must not depend on packages with lower priority
801 values (excluding build-time dependencies). In order to
802 ensure this, the priorities of one or more packages may need
808 <heading>Binary packages</heading>
811 The Debian GNU/Linux distribution is based on the Debian
812 package management system, called <prgn>dpkg</prgn>. Thus,
813 all packages in the Debian distribution must be provided
814 in the <tt>.deb</tt> file format.</p>
818 <heading>The package name</heading>
821 Every package must have a name that's unique within the Debian
825 Package names must consist of lower case letters (a-z),
826 digits (0-9), plus (+) and minus (-) signs, and periods
827 (.). They must be at least two characters long and must
828 contain at least one letter.
832 The package name is part of the file name of the
833 <tt>.deb</tt> file and is included in the control field
839 <heading>The maintainer of a package</heading>
841 Every package must have a Debian maintainer (the
842 maintainer may be one person or a group of people
843 reachable from a common email address, such as a mailing
844 list). The maintainer is responsible for ensuring that
845 the package is placed in the appropriate distributions.
849 The maintainer must be specified in the
850 <tt>Maintainer</tt> control field with their correct name
851 and a working email address. If one person maintains
852 several packages, he/she should try to avoid having
853 different forms of their name and email address in
854 the <tt>Maintainer</tt> fields of those packages.
858 If the maintainer of a package quits from the Debian
859 project, "Debian QA Group"
860 <email>packages@qa.debian.org</email> takes over the
861 maintainership of the package until someone else
862 volunteers for that task. These packages are called
863 <em>orphaned packages</em>.
866 The detailed procedure for doing this gracefully can
867 be found in the Debian Developer's Reference, either
868 in the <tt>developers-reference</tt> package, or on
869 the Debian FTP server
870 <ftpsite>ftp.debian.org</ftpsite> as
871 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
873 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
874 name="Debian Developer's Reference"> webpage.
882 <heading>The description of a package</heading>
885 Every Debian package must have an extended description
886 stored in the appropriate field of the control record.</p>
889 The description should be written so that it gives the
890 system administrator enough information to decide whether
891 to install the package. This description should not just
892 be copied verbatim from the program's documentation.
893 Instructions for configuring or using the package should
894 not be included -- that is what installation scripts,
895 manual pages, info files, etc., are for. Copyright
896 statements and other administrivia should not be included
897 either -- that is what the copyright file is for.</p>
902 <heading>Dependencies</heading>
905 Every package must specify the dependency information
906 about other packages that are required for the first to
910 For example, a dependency entry must be provided for any
911 shared libraries required by a dynamically-linked executable
912 binary in a package.</p>
915 Packages are not required to declare any dependencies they
916 have on other packages which are marked <tt>Essential</tt>
917 (see below), and should not do so unless they depend on a
918 particular version of that package.</p>
921 Sometimes, a package requires another package to be installed
922 <em>and</em> configured before it can be installed. In this
923 case, you must specify a <tt>Pre-Depends</tt> entry for
927 You should not specify a <tt>Pre-Depends</tt> entry for a
928 package before this has been discussed on the
929 <tt>debian-devel</tt> mailing list and a consensus about
930 doing that has been reached.</p></sect1>
934 <heading>Virtual packages</heading>
937 Sometimes, there are several packages which offer
938 more-or-less the same functionality. In this case, it's
939 useful to define a <em>virtual package</em> whose name
940 describes that common functionality. (The virtual
941 packages only exist logically, not physically--that's why
942 they are called <em>virtual</em>.) The packages with this
943 particular function will then <em>provide</em> the virtual
944 package. Thus, any other package requiring that function
945 can simply depend on the virtual package without having to
946 specify all possible packages individually.</p>
949 All packages should use virtual package names where
950 appropriate, and arrange to create new ones if necessary.
951 They should not use virtual package names (except privately,
952 amongst a cooperating group of packages) unless they have
953 been agreed upon and appear in the list of virtual package
957 The latest version of the authoritative list of virtual
958 package names can be found on
959 <ftpsite>ftp.debian.org</ftpsite> in
960 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
961 or your local mirror. In addition, it is included in the
962 <tt>debian-policy</tt> package. The procedure for updating
963 the list is described at the top of the file.</p></sect1>
967 <heading>Base packages</heading>
970 The packages included in the <tt>base</tt> section have a
971 special function. They form a minimum subset of the Debian
972 GNU/Linux system that is installed before everything else
973 on a new system. Thus, only very few packages are allowed
974 to go into the <tt>base</tt> section to keep the required
975 disk usage very small.</p>
978 Most of these packages will have the priority value
979 <tt>required</tt> or at least <tt>important</tt>, and many
980 of them will be tagged <tt>essential</tt> (see below).</p>
983 You must not place any packages into the <tt>base</tt>
984 section before this has been discussed on the
985 <tt>debian-devel</tt> mailing list and a consensus about
986 doing that has been reached.</p></sect1>
990 <heading>Essential packages</heading>
993 Some packages are tagged <tt>essential</tt>. (They have
994 <tt>Essential: yes</tt> in their package control record.)
995 This flag is used for packages that are <em>essential</em>
999 Since these packages cannot be easily removed (one has to
1000 specify an extra <em>force option</em> to
1001 <prgn>dpkg</prgn> to do so), this flag must not be used
1002 unless absolutely necessary. A shared library package
1003 must not be tagged <tt>essential</tt>--dependencies will
1004 prevent its premature removal, and we need to be able to
1005 remove it when it has been superseded.
1009 Since dpkg will not prevent upgrading of other packages
1010 while an <tt>essential</tt> package is in an unconfigured
1011 state, all <tt>essential</tt> packages must supply all of
1012 their core functionality even when unconfigured. If the
1013 package cannot satisfy this requirement it must not be
1014 tagged as essential, and any packages depending on this
1015 package must instead have explicit dependency fields as
1020 You must not tag any packages <tt>essential</tt> before
1021 this has been discussed on the <tt>debian-devel</tt>
1022 mailing list and a consensus about doing that has been
1028 <heading>Maintainer scripts</heading>
1031 The package installation scripts should avoid producing
1032 output which it is unnecessary for the user to see and
1033 should rely on <prgn>dpkg</prgn> to stave off boredom on
1034 the part of a user installing many packages. This means,
1035 amongst other things, using the <tt>--quiet</tt> option on
1036 <prgn>install-info</prgn>.</p>
1039 Errors which occur during the execution of an installation
1040 script must be checked and the installation must not
1041 continue after an error.
1045 Note that in general <ref id="scripts"> applies to package
1046 maintainer scripts, too.
1050 You should not use <tt>dpkg-divert</tt> on a file
1051 belonging to another package without consulting the
1052 maintainer of that package first.
1055 All packages which supply an instance of a common command
1056 name (or, in general, filename) should generally use
1057 <prgn>update-alternatives</prgn>, so that they may be
1058 installed together. If <prgn>update-alternatives</prgn>
1059 is not used, then each package must use
1060 <var>Conflicts</var> to ensure that other packages are
1061 de-installed. (In this case, it may be appropriate to
1062 specify a conflict against earlier versions of something
1063 that previously did not use
1064 <prgn>update-alternatives</prgn> - this is an exception to
1065 the usual rule that versioned conflicts should be
1071 <heading>Prompting in maintainer scripts</heading>
1073 Package maintainer scripts may prompt the user if
1074 necessary. Prompting may be accomplished by hand, or by
1075 communicating with a program, such as
1076 <prgn>debconf</prgn>, which conforms to the Debian
1077 Configuration management specification, version 2 or
1078 higher. These are included in the
1079 <file>debconf_specification</file> files in the
1080 <package>debian-policy</package> package.
1081 You may also find this file on the FTP site
1082 <ftpsite>ftp.debian.org</ftpsite> in
1083 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1084 or on your local mirror.
1087 2.5% of Debian packages [see <url
1088 id="http://kitenet.net/programs/debconf/stats/">]
1089 currently use <package>debconf</package> to prompt
1090 the user at install time, and this number is growing
1091 daily. The benefits of using debconf are briefly
1093 id="http://kitenet.net/doc/debconf-doc/introduction.html">;
1094 they include preconfiguration, (mostly)
1095 noninteractive installation, elimination of
1096 redundant prompting, consistency of user interface,
1100 With this increasing number of packages using
1101 <package>debconf</package>, plus the existance of a
1102 nascent second implementation of the Debian
1103 configuration management system
1104 (<package>cdebconf</package>), and the stabalization
1105 of the protocol these things use, the time has
1106 finally come to reflect the use of these things in
1113 Packages which use the Debian Configuration management
1114 specification may contain an additional
1115 <file>config</file> script and a <file>templates</file>
1116 file in their control archive. The <prgn>config</prgn>
1117 script might be run before the <prgn>preinst</prgn>
1118 script, and before the package is unpacked or any of its
1119 dependancies or pre-dependancies are satisfied.
1120 Therefore it must work using only the tools present in
1121 <em>essential</em> packages.
1124 <package>Debconf</package> or another tool that
1125 implements the Debian Configuration management
1126 specification will also be installed, and any
1127 versioned dependencies on it will be satisfied
1128 before preconfiguration begins.
1134 Packages should try to minimize the amount of prompting
1135 they need to do, and they should ensure that the user
1136 will only ever be asked each question once. This means
1137 that packages should try to use appropriate shared
1138 configuration files (such as <tt>/etc/papersize</tt> and
1139 <tt>/etc/news/server</tt>), and shared
1140 <package>debconf</package> variables rather than each
1141 prompting for their own list of required pieces of
1146 It also means that an upgrade should not ask the same
1147 questions again, unless the user has used <tt>dpkg
1148 --purge</tt> to remove the package's configuration. The
1149 answers to configuration questions should be stored in an
1150 appropriate place in <tt>/etc</tt> so that the user can
1151 modify them, and how this has been done should be
1155 If a package has a vitally important piece of
1156 information to pass to the user (such as "don't run me
1157 as I am, you must edit the following configuration files
1158 first or you risk your system emitting badly-formatted
1159 messages"), it should display this in the
1160 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1161 prompt the user to hit return to acknowledge the
1162 message. Copyright messages do not count as vitally
1163 important (they belong in
1164 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1165 neither do instructions on how to use a program (these
1166 should be in on-line documentation, where all the users
1170 Any necessary prompting should almost always be confined
1171 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1172 script. If it is done in the <prgn>postinst</prgn>, it
1173 should be protected with a conditional so that unnecessary
1174 prompting doesn't happen if a package's installation fails
1175 and the <prgn>postinst</prgn> is called with
1176 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1177 <tt>abort-deconfigure</tt>.</p>
1182 <heading>Source packages</heading>
1185 <heading>Standards conformance</heading>
1186 <sect id="standardsversion">
1189 In the source package's <tt>Standards-Version</tt> control
1190 field, you must specify the most recent version number of
1191 this policy document with which your package complies.
1192 The current version number is &version;.
1196 This information may be used to file bug reports
1197 automatically if your package becomes too much out of
1202 The version number has four components--major and minor
1203 version number and major and minor patch level. When the
1204 standards change in a way that requires every package to
1205 change the major number will be changed. Significant
1206 changes that will require work in many packages will be
1207 signaled by a change to the minor number. The major patch
1208 level will be changed for any change to the meaning of the
1209 standards, however small; the minor patch level will be
1210 changed when only cosmetic, typographical or other edits
1211 are made which neither change the meaning of the document
1212 nor affect the contents of packages.</p>
1215 Thus only the first three components of the policy version
1216 are significant in the <em>Standards-Version</em> control
1217 field, and so either these three components or the all
1218 four components may be specified.
1221 In the past, people specified the full version number
1222 in the Standards-Version field, for example `2.3.0.0'.
1223 Since minor patch-level changes don't introduce new
1224 policy, it was thought it would be better to relax
1225 policy and only require the first 3 components to be
1226 specified, in this example `2.3.0'. All four
1227 components may still be used if someone wishes to do
1234 You should regularly, and especially if your package has
1235 become out of date, check for the newest Policy Manual
1236 available and update your package, if necessary. When your
1237 package complies with the new standards you should update the
1238 <tt>Standards-Version</tt> source package field and
1242 See the file <tt>upgrading-checklist</tt> for
1243 information about policy which has changed between
1244 different versions of this document.
1252 <heading>Package relationships</heading>
1255 Source packages should specify which binary packages they
1256 require to be installed or not to be installed in order to
1257 build correctly. For example, if building a package
1258 requires a certain compiler, then the compiler should be
1259 specified as a build-time dependency.
1263 It is not necessary to explicitly specify build-time
1264 relationships on a minimal set of packages that are always
1265 needed to compile, link and put in a Debian package a
1266 standard "Hello World!" program written in C or C++. The
1267 required packages are called <em>build-essential</em>, and
1268 an informational list can be found in
1269 <tt>/usr/share/doc/build-essential/list</tt> (which is
1270 contained in the <tt>build-essential</tt>
1276 <p>This allows maintaining the list separately
1277 from the policy documents (the list does not
1278 need the kind of control that the policy
1284 Having a separate package allows one to install
1285 the build-essential packages on a machine, as
1286 well as allowing other packages such as task
1287 packages to require installation of the
1288 build-essential packages using the depends
1294 The separate package allows bug reports against
1295 the list to be categorized separately from
1296 the policy management process in the BTS.
1306 When specifying the set of build-time dependencies, one
1307 should list only those packages explicitly required by the
1308 build. It is not necessary to list packages which are
1309 required merely because some other package in the list of
1310 build-time dependencies depends on them.
1313 The reason for this is that dependencies change, and
1314 you should list all those packages, and <em>only</em>
1315 those packages that <em>you</em> need directly. What
1316 others need is their business. For example, if you
1317 only link against <tt>libimlib</tt>, you will need to
1318 build-depend on <package>libimlib2-dev</package> but
1319 not against any <tt>libjpeg*</tt> packages, even
1320 though <tt>libimlib2-dev</tt> currently depends on
1321 them: installation of <package>libimlib2-dev</package>
1322 will automatically ensure that all of its run-time
1323 dependencies are satisfied.
1329 If build-time dependencies are specified, it must be
1330 possible to build the package and produce working binaries
1331 on a system with only essential and build-essential
1332 packages installed and also those required to satisfy the
1333 build-time relationships (including any implied
1334 relationships). In particular, this means that version
1335 clauses should be used rigorously in build-time
1336 relationships so that one cannot produce bad or
1337 inconsistently configured packages when the relationships
1338 are properly satisfied.
1342 <heading>Changes to the upstream sources</heading>
1345 If changes to the source code are made that are not
1346 specific to the needs of the Debian system, they should be
1347 sent to the upstream authors in whatever form they prefer
1348 so as to be included in the upstream version of the
1352 If you need to configure the package differently for
1353 Debian or for Linux, and the upstream source doesn't
1354 provide a way to do so, you should add such configuration
1355 facilities (for example, a new <prgn>autoconf</prgn> test
1356 or <tt>#define</tt>) and send the patch to the upstream
1357 authors, with the default set to the way they originally
1358 had it. You can then easily override the default in your
1359 <tt>debian/rules</tt> or wherever is appropriate.</p>
1362 You should make sure that the <prgn>configure</prgn> utility
1363 detects the correct architecture specification string
1364 (refer to <ref id="arch-spec"> for details).</p>
1367 If you need to edit a <prgn>Makefile</prgn> where
1368 GNU-style <prgn>configure</prgn> scripts are used, you
1369 should edit the <tt>.in</tt> files rather than editing the
1370 <prgn>Makefile</prgn> directly. This allows the user to
1371 reconfigure the package if necessary. You should
1372 <em>not</em> configure the package and edit the generated
1373 <prgn>Makefile</prgn>! This makes it impossible for
1374 someone else to later reconfigure the package.</p></sect1>
1378 <heading>Documenting your changes</heading>
1381 You should document your changes and updates to the source
1382 package properly in the <tt>debian/changelog</tt> file. (Note
1383 that mistakes in changelogs are usually best rectified by
1384 making a new changelog entry rather than "rewriting history"
1385 by editing old changelog entries.)</p>
1388 In non-experimental packages you must use a format for
1389 <tt>debian/changelog</tt> which is supported by the most
1390 recent released version of <prgn>dpkg</prgn>.
1393 If you wish to use an alternative format, you may do
1394 so as long as you include a parser for it in your
1395 source package. The parser must have an API
1396 compatible with that expected by
1397 <prgn>dpkg-genchanges</prgn> and
1398 <prgn>dpkg-gencontrol</prgn>. If there is general
1399 interest in the new format, you should contact the
1400 <package>dpkg</package> maintainer to have the parser
1401 script for it included in the <prgn>dpkg</prgn>
1402 package. (You will need to agree that the parser and
1403 its manpage may be distributed under the GNU GPL, just
1404 as the rest of `dpkg' is.)
1412 <heading>Error trapping in makefiles</heading>
1415 When <prgn>make</prgn> invokes a command in a makefile
1416 (including your package's upstream makefiles and
1417 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1418 means that <tt>sh</tt>'s usual bad error handling
1419 properties apply: if you include a miniature script as one
1420 of the commands in your makefile you'll find that if you
1421 don't do anything about it then errors are not detected
1422 and <prgn>make</prgn> will blithely continue after
1426 Every time you put more than one shell command (this
1427 includes using a loop) in a makefile command you
1428 must make sure that errors are trapped. For
1429 simple compound commands, such as changing directory and
1430 then running a program, using <tt>&&</tt> rather
1431 than semicolon as a command separator is sufficient. For
1432 more complex commands including most loops and
1433 conditionals you should include a separate <tt>set -e</tt>
1434 command at the start of every makefile command that's
1435 actually one of these miniature shell scripts.</p></sect1>
1439 <heading>Obsolete constructs and libraries</heading>
1442 The include file <prgn><varargs.h></prgn> is
1443 provided to support end-users compiling very old software;
1444 the library <tt>libtermcap</tt> is provided to support the
1445 execution of software which has been linked against it
1446 (either old programs or those such as Netscape which are
1447 only available in binary form).</p>
1450 Debian packages should be patched to use
1451 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1458 <chapt id="controlfields"><heading>Control files and their fields</heading>
1461 Many of the tools in the package management suite manipulate
1462 data represented in a common format, known as <em>control
1463 data</em>. The data is often stored in <em>control
1464 files</em>. Binary and source packages have control files,
1465 and the <tt>.changes</tt> files which control the installation
1466 of uploaded files are also in control file format.
1467 <prgn>Dpkg</prgn>'s internal databases are in a similar
1471 <sect><heading>Syntax of control files</heading>
1474 A control file consists of one or more paragraphs of fields.
1475 The paragraphs are separated by blank lines. Some control
1476 files allow only one paragraph; others allow several, in
1477 which case each paragraph usually refers to a different
1478 package. (For example, in source packages, the first
1479 paragraph refers to the source package, and later paragraphs
1480 refer to binary packages generated from the source.)
1484 Each paragraph consists of a series of data fields; each
1485 field consists of the field name, followed by a colon and
1486 then the data/value associated with that field. It ends at
1487 the end of the line. Horizontal whitespace (spaces and
1488 tabs) may occur immediately before or after the value and is
1489 ignored there; it is conventional to put a single space
1490 after the colon. For example, a field might be:
1494 the field name is <tt>Package</tt> and the field value
1499 Some fields' values may span several lines; in this case
1500 each continuation line <em>must</em> start with a space or
1501 tab. Any trailing spaces or tabs at the end of individual
1502 lines of a field value are ignored.
1506 Except where otherwise stated only a single line of data is
1507 allowed and whitespace is not significant in a field body.
1508 Whitespace must not appear inside names (of packages,
1509 architectures, files or anything else) or version numbers,
1510 or between the characters of multi-character version
1515 Field names are not case-sensitive, but it is usual to
1516 capitalize the field names using mixed case as shown below.
1520 Blank lines, or lines consisting only of spaces and tabs,
1521 are not allowed within field values or between fields - that
1522 would mean a new paragraph.
1527 <sect><heading>List of fields</heading>
1529 This list here is not supposed to be exhaustive. Most fields
1530 are dealt with elsewhere in this document.
1532 <sect1 id="f-Package"><heading><tt>Package</tt>
1536 The name of the binary package. Package names consist of
1537 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1538 (plus, minus and full stop).
1542 They must be at least two characters long and must start
1543 with an alphanumeric character and not be all digits. The
1544 use of lowercase package names is strongly recommended
1545 unless the package you're building (or referring to, in
1546 other fields) is already using uppercase.</p>
1549 <sect1 id="f-Version"><heading><tt>Version</tt>
1553 This lists the source or binary package's version number -
1554 see <ref id="versions">.
1560 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1564 The most recent version of the standards (the policy
1565 manual and associated texts) with which the package
1566 complies. This is updated manually when editing the
1567 source package to conform to newer standards; it can
1568 sometimes be used to tell when a package needs attention.
1569 Its format is described above; see
1570 <ref id="standardsversion">.
1575 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1579 In a <tt>.changes</tt> file or parsed changelog output
1580 this contains the (space-separated) name(s) of the
1581 distribution(s) where this version of the package should
1582 be installed. Valid distributions are determined by the
1583 archive maintainers.
1585 Current distribution names are:
1587 <tag><em>stable</em></tag>
1590 This is the current `released' version of Debian
1591 GNU/Linux. Once the distribution is
1592 <em>stable</em> only security fixes and other
1593 major bug fixes are allowed. When changes are
1594 made to this distribution, the release number is
1595 increased (for example: 2.2r1 becomes 2.2r2 then
1600 <tag><em>unstable</em></tag>
1603 This distribution value refers to the
1604 <em>developmental</em> part of the Debian
1605 distribution tree. New packages, new upstream
1606 versions of packages and bug fixes go into the
1607 <em>unstable</em> directory tree. Download from
1608 this distribution at your own risk.
1612 <tag><em>testing</em></tag>
1615 This distribution value refers to the
1616 <em>testing</em> part of the Debian distribution
1617 tree. It receives its packages from the
1618 unstable distribution after a short time lag to
1619 ensure that there are no major issues with the
1620 unstable packages. It is less prone to breakage
1621 than unstable, but still risky. It is not
1622 possible to upload packages directly to
1627 <tag><em>frozen</em></tag>
1630 From time to time, the <em>frozen</em>
1631 distribution enters a state of `code-freeze' in
1632 anticipation of release as a <em>stable</em>
1633 version. During this period of testing only
1634 fixes for existing or newly-discovered bugs will
1635 be allowed. The exact details of this stage are
1636 determined by the Release Manager.
1640 <tag><em>experimental</em></tag>
1643 The packages with this distribution value are
1644 deemed by their maintainers to be high
1645 risk. Oftentimes they represent early beta or
1646 developmental packages from various sources that
1647 the maintainers want people to try, but are not
1648 ready to be a part of the other parts of the
1649 Debian distribution tree. Download at your own
1655 You should list <em>all</em> distributions that the
1656 package should be installed into.
1665 <chapt id="versions"><heading>Version numbering</heading>
1668 Every package has a version number recorded in its
1669 <tt>Version</tt> control file field.
1673 The package management system imposes an ordering on version
1674 numbers, so that it can tell whether packages are being up- or
1675 downgraded and so that package system front end applications
1676 can tell whether a package it finds available is newer than
1677 the one installed on the system. The version number format
1678 has the most significant parts (as far as comparison is
1679 concerned) at the beginning.
1683 The version number format is:
1684 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1688 The three components here are:
1690 <tag><var>epoch</var></tag>
1694 This is a single (generally small) unsigned integer. It
1695 may be omitted, in which case zero is assumed. If it is
1696 omitted then the <var>upstream_version</var> may not
1701 It is provided to allow mistakes in the version numbers
1702 of older versions of a package, and also a package's
1703 previous version numbering schemes, to be left behind.
1708 <tag><var>upstream_version</var></tag>
1712 This is the main part of the version number. It is
1713 usually the version number of the original (`upstream')
1714 package from which the <tt>.deb</tt> file has been made,
1715 if this is applicable. Usually this will be in the same
1716 format as that specified by the upstream author(s);
1717 however, it may need to be reformatted to fit into the
1718 package management system's format and comparison
1723 The comparison behavior of the package management system
1724 with respect to the <var>upstream_version</var> is
1725 described below. The <var>upstream_version</var>
1726 portion of the version number is mandatory.
1730 The <var>upstream_version</var> may contain only
1733 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1735 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1736 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1737 start with a digit. If there is no
1738 <var>debian_revision</var> then hyphens are not allowed;
1739 if there is no <var>epoch</var> then colons are not
1743 <tag><var>debian_revision</var></tag>
1747 This part of the version number specifies the version of
1748 the Debian package based on the upstream version. It
1749 may contain only alphanumerics and the characters
1750 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1751 compared in the same way as the
1752 <var>upstream_version</var> is.
1756 It is optional; if it isn't present then the
1757 <var>upstream_version</var> may not contain a hyphen.
1758 This format represents the case where a piece of
1759 software was written specifically to be turned into a
1760 Debian package, and so there is only one `debianization'
1761 of it and therefore no revision indication is required.
1765 It is conventional to restart the
1766 <var>debian_revision</var> at <tt>1</tt> each time the
1767 <var>upstream_version</var> is increased.
1771 The package management system will break the version
1772 number apart at the last hyphen in the string (if there
1773 is one) to determine the <var>upstream_version</var> and
1774 <var>debian_revision</var>. The absence of a
1775 <var>debian_revision</var> compares earlier than the
1776 presence of one (but note that the
1777 <var>debian_revision</var> is the least significant part
1778 of the version number).
1782 The <var>upstream_version</var> and <var>debian_revision</var>
1783 parts are compared by the package management system using the
1788 The strings are compared from left to right.
1792 First the initial part of each string consisting entirely of
1793 non-digit characters is determined. These two parts (one of
1794 which may be empty) are compared lexically. If a difference
1795 is found it is returned. The lexical comparison is a
1796 comparison of ASCII values modified so that all the letters
1797 sort earlier than all the non-letters.
1801 Then the initial part of the remainder of each string which
1802 consists entirely of digit characters is determined. The
1803 numerical values of these two parts are compared, and any
1804 difference found is returned as the result of the comparison.
1805 For these purposes an empty string (which can only occur at
1806 the end of one or both version strings being compared) counts
1811 These two steps (comparing and removing initial non-digit
1812 strings and initial digit strings) are repeated until a
1813 difference is found or both strings are exhausted.
1817 Note that the purpose of epochs is to allow us to leave behind
1818 mistakes in version numbering, and to cope with situations
1819 where the version numbering scheme changes. It is
1820 <em>not</em> intended to cope with version numbers containing
1821 strings of letters which the package management system cannot
1822 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1823 silly orderings (the author of this manual has heard of a
1824 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1825 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1826 <tt>2</tt> and so forth).
1830 If an upstream package has problematic version numbers they
1831 should be converted to a sane form for use in the
1832 <tt>Version</tt> field.
1836 <heading>Version numbers based on dates</heading>
1838 In general, Debian packages should use the same version
1839 numbers as the upstream sources.</p>
1842 However, in some cases where the upstream version number is
1843 based on a date (e.g., a development `snapshot' release) the
1844 package management system cannot handle these version
1845 numbers without epochs. For example, dpkg will consider
1846 `96May01' to be greater than `96Dec24'.</p>
1849 To prevent having to use epochs for every new upstream
1850 version, the version number should be changed to the
1851 following format in such cases: `19960501', `19961224'. It
1852 is up to the maintainer whether he/she wants to bother the
1853 upstream maintainer to change the version numbers upstream,
1857 Note that other version formats based on dates which are
1858 parsed correctly by the package management system should
1859 <em>not</em> be changed.</p>
1862 Native Debian packages (i.e., packages which have been
1863 written especially for Debian) whose version numbers include
1864 dates should always use the `YYYYMMDD' format.</p>
1868 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1870 <sect id="timestamps"><heading>Time Stamps</heading>
1872 Maintainers should preserve the modification times of the
1873 upstream source files in a package, as far as is reasonably
1877 The rationale is that there is some information conveyed
1878 by knowing the age of the file, for example, you could
1879 recognize that some documentation is very old by looking
1880 at the modification time, so it would be nice if the
1881 modification time of the upstream source would be
1888 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1889 main building script</heading>
1892 This file must be an executable makefile, and contains the
1893 package-specific recipes for compiling the package and
1894 building binary package(s) from the source.
1898 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1899 so that it can be invoked by saying its name rather than
1900 invoking <prgn>make</prgn> explicitly.
1904 Since an interactive <tt>debian/rules</tt> script makes it
1905 impossible to auto-compile that package and also makes it
1906 hard for other people to reproduce the same binary
1907 package, all <em>required targets</em> MUST be
1908 non-interactive. At a minimum, required targets are the
1909 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1910 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1911 <em>binary-indep</em>, and <em>build</em>. It also follows
1912 that any target that these targets depend on must also be
1917 The required and optional targets are as follows:
1919 <tag><tt>build</tt></tag>
1922 This should perform all non-interactive configuration
1923 and compilation of the package. If a package has an
1924 interactive pre-build configuration routine, the
1925 Debianized source package must either be built after
1926 this has taken place (so that the binary package can
1927 be built without rerunning the configuration) or the
1928 configuration routine modified to become
1929 non-interactive. (The latter is preferable if there
1930 are architecture-specific features detected by the
1931 configuration routine.)
1935 For some packages, notably ones where the same
1936 source tree is compiled in different ways to produce
1937 two binary packages, the <prgn>build</prgn> target
1938 does not make much sense. For these packages it is
1939 good enough to provide two (or more) targets
1940 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1941 for each of the ways of building the package, and a
1942 <prgn>build</prgn> target that does nothing. The
1943 <prgn>binary</prgn> target will have to build the
1944 package in each of the possible ways and make the
1945 binary package out of each.
1949 The <prgn>build</prgn> target must not do anything
1950 that might require root privilege.
1954 The <prgn>build</prgn> target may need to run the
1955 <prgn>clean</prgn> target first - see below.
1959 When a package has a configuration and build routine
1960 which takes a long time, or when the makefiles are
1961 poorly designed, or when <prgn>build</prgn> needs to
1962 run <prgn>clean</prgn> first, it is a good idea to
1963 <tt>touch build</tt> when the build process is
1964 complete. This will ensure that if <tt>debian/rules
1965 build</tt> is run again it will not rebuild the whole
1969 Another common way to do this is for <prgn>build</prgn>
1970 to depend on <prgn>build-stamp</prgn> and to do
1971 nothing else, and for the <prgn>build-stamp</prgn>
1972 target to do the building and to <tt>touch
1973 build-stamp</tt> on completion. This is
1974 especially useful if the build routine creates a
1975 file or directory called <tt>build</tt>; in such a
1976 case, <prgn>build</prgn> will need to be listed as
1977 a phony target (i.e., as a dependency of the
1978 <tt>.PHONY</tt> target). See the documentation of
1979 <prgn>make</prgn> for more information on phony
1986 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1987 <tt>binary-indep</tt>
1991 The <prgn>binary</prgn> target must be all that is
1992 necessary for the user to build the binary package(s)
1993 produced from this source package. All of these
1994 targets are required to be non-interactive. It is
1995 split into two parts: <prgn>binary-arch</prgn> builds
1996 the binary packages which are specific to a particular
1997 architecture, and <prgn>binary-indep</prgn> builds
1998 those which are not.
2002 <prgn>binary</prgn> may be (and commonly is) a target
2003 with no commands which simply depends on
2004 <prgn>binary-arch</prgn> and
2005 <prgn>binary-indep</prgn>.
2009 Each <prgn>binary-*</prgn> target should depend on
2010 the <prgn>build</prgn> target, above, so that the
2011 package is built if it has not been already. It
2012 should then create the relevant binary package(s),
2013 using <prgn>dpkg-gencontrol</prgn> to make their
2014 control files and <prgn>dpkg-deb</prgn> to build
2015 them and place them in the parent of the top level
2020 Both the <prgn>binary-arch</prgn> and
2021 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2022 If one of them has nothing to do (which will always be
2023 the case if the source generates only a single binary
2024 package, whether architecture-dependent or not), it
2025 must still exist and must always succeed.
2029 The <prgn>binary</prgn> targets must be invoked as
2033 The <prgn>fakeroot</prgn> package often allows one
2034 to build a package correctly even without being
2041 <tag><tt>clean</tt></tag>
2045 This must undo any effects that the <prgn>build</prgn>
2046 and <prgn>binary</prgn> targets may have had, except
2047 that it should leave alone any output files created in
2048 the parent directory by a run of a <prgn>binary</prgn>
2049 target. This target must be non-interactive.
2053 If a <prgn>build</prgn> file is touched at the end of
2054 the <prgn>build</prgn> target, as suggested above, it
2055 should be removed as the first action that
2056 <prgn>clean</prgn> performs, so that running
2057 <prgn>build</prgn> again after an interrupted
2058 <prgn>clean</prgn> doesn't think that everything is
2063 The <prgn>clean</prgn> target may need to be
2064 invoked as root if <prgn>binary</prgn> has been
2065 invoked since the last <prgn>clean</prgn>, or if
2066 <prgn>build</prgn> has been invoked as root (since
2067 <prgn>build</prgn> may create directories, for
2072 <tag><tt>get-orig-source</tt> (optional)</tag>
2076 This target fetches the most recent version of the
2077 original source package from a canonical archive site
2078 (via FTP or WWW, for example), does any necessary
2079 rearrangement to turn it into the original source
2080 tar file format described below, and leaves it in the
2085 This target may be invoked in any directory, and
2086 should take care to clean up any temporary files it
2091 This target is optional, but providing it if
2092 possible is a good idea.
2098 The <prgn>build</prgn>, <prgn>binary</prgn> and
2099 <prgn>clean</prgn> targets must be invoked with the current
2100 directory being the package's top-level directory.
2105 Additional targets may exist in <tt>debian/rules</tt>,
2106 either as published or undocumented interfaces or for the
2107 package's internal use.
2111 The architectures we build on and build for are determined
2112 by <prgn>make</prgn> variables using
2113 <prgn>dpkg-architecture</prgn>. You can determine the
2114 Debian architecture and the GNU style architecture
2115 specification string for the build machine (the machine type
2116 we are building on) as well as for the host machine (the
2117 machine type we are building for). Here is a list of
2118 supported <prgn>make</prgn> variables:
2119 <list compact="compact">
2121 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2124 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2125 specification string)</p>
2128 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2129 <tt>DEB_*_GNU_TYPE</tt>)</p>
2132 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2133 <tt>DEB_*_GNU_TYPE</tt>)</p>
2135 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2136 the build machine or <tt>HOST</tt> for specification of the
2141 Backward compatibility can be provided in the rules file
2142 by setting the needed variables to suitable default
2143 values; please refer to the documentation of
2144 <prgn>dpkg-architecture</prgn> for details.
2148 It is important to understand that the <tt>DEB_*_ARCH</tt>
2149 string only determines which Debian architecture we are
2150 building on or for. It should not be used to get the CPU
2151 or system information; the GNU style variables should be
2156 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2160 This file records the changes to the Debian-specific parts of the
2164 Though there is nothing stopping an author who is also
2165 the Debian maintainer from using it for all their
2166 changes, it will have to be renamed if the Debian and
2167 upstream maintainers become different people. In such a
2168 case, however, it might be better to maintain the
2169 package as a non-native package.
2175 It has a special format which allows the package building
2176 tools to discover which version of the package is being
2177 built and find out other release-specific information.
2181 That format is a series of entries like this:
2183 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2185 * <var>change details</var>
2186 <var>more change details</var>
2187 * <var>even more change details</var>
2189 -- <var>maintainer name and email address</var> <var>date</var>
2194 <var>package</var> and <var>version</var> are the source
2195 package name and version number.
2199 <var>distribution(s)</var> lists the distributions where
2200 this version should be installed when it is uploaded - it
2201 is copied to the <tt>Distribution</tt> field in the
2202 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2206 <var>urgency</var> is the value for the <tt>Urgency</tt>
2207 field in the <tt>.changes</tt> file for the upload. It is
2208 not possible to specify an urgency containing commas; commas
2209 are used to separate
2210 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2211 <prgn>dpkg</prgn> changelog format (though there is
2212 currently only one useful <var>keyword</var>,
2216 Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
2217 <tt>high</tt> and <tt>critical</tt>. They have an
2218 effect on how quickly a package will be considered for
2219 inclusion into the <tt>testing</tt> distribution, and
2220 give an indication of the importance of any fixes
2221 included in this upload.
2227 The change details may in fact be any series of lines
2228 starting with at least two spaces, but conventionally each
2229 change starts with an asterisk and a separating space and
2230 continuation lines are indented so as to bring them in
2231 line with the start of the text above. Blank lines may be
2232 used here to separate groups of changes, if desired.
2236 If this upload resolves bugs recorded in the Bug Tracking
2237 System (BTS), they may be automatically closed on the
2238 inclusion of this package into the Debian archive by
2239 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2240 in the change details.
2243 To be precise, the string should match the following
2244 Perl regular expression:
2246 <tt>/closes:\s*(?:bug)?\#\s?\d+(?:,\s*(?:bug)?\#\s?\d+)*/i</tt>
2248 Then all of the bug numbers listed will be closed by the
2249 archive maintenance script (<prgn>katie</prgn>), or in
2250 the case of an NMU, marked as fixed.
2256 The maintainer name and email address used in the changelog
2257 should be the details of the person uploading <em>this</em>
2258 version. They are <em>not</em> necessarily those of the
2259 usual package maintainer. The information here will be
2260 copied to the <tt>Changed-By</tt> field in the
2261 <tt>.changes</tt> file, and then later used to send an
2262 acknowledgement when the upload has been installed.
2266 The <var>date</var> should be in RFC822 format
2269 This is generated by the <prgn>822-date</prgn>
2272 </footnote>; it should include the time zone specified
2273 numerically, with the time zone name or abbreviation
2274 optionally present as a comment in parentheses.
2278 The first `title' line with the package name should start
2279 at the left hand margin; the `trailer' line with the
2280 maintainer and date details should be preceded by exactly
2281 one space. The maintainer details and the date must be
2282 separated by exactly two spaces.
2285 <sect1><heading>Defining alternative changelog formats</heading>
2288 It is possible to use a different format to the standard
2289 one, by providing a parser for the format you wish to
2293 A changelog parser must not interact with the user at
2299 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2300 and variable substitutions </heading>
2303 When <prgn>dpkg-gencontrol</prgn>,
2304 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2305 generate control files they perform variable substitutions
2306 on their output just before writing it. Variable
2307 substitutions have the form
2308 <tt>${<var>variable-name</var>}</tt>. The optional file
2309 <tt>debian/substvars</tt> contains variable substitutions to
2310 be used; variables can also be set directly from
2311 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2312 source packaging commands, and certain predefined variables
2317 The <tt>debian/substvars</tt> file is usually generated and
2318 modified dynamically by <tt>debian/rules</tt> targets; in
2319 this case it must be removed by the <prgn>clean</prgn>
2324 See <manref name="dpkg-source" section="1"> for full
2325 details about source variable substitutions, including the
2326 format of <tt>debian/substvars</tt>.</p>
2329 <sect id="debianfiles"><heading><tt>debian/files</tt>
2333 This file is not a permanent part of the source tree; it
2334 is used while building packages to record which files are
2335 being generated. <prgn>dpkg-genchanges</prgn> uses it
2336 when it generates a <tt>.changes</tt> file.
2340 It should not exist in a shipped source package, and so it
2341 (and any backup files or temporary files such as
2345 <tt>files.new</tt> is used as a temporary file by
2346 <prgn>dpkg-gencontrol</prgn> and
2347 <prgn>dpkg-distaddfile</prgn> - they write a new
2348 version of <tt>files</tt> here before renaming it,
2349 to avoid leaving a corrupted copy if an error
2352 </footnote>) should be removed by the
2353 <prgn>clean</prgn> target. It may also be wise to
2354 ensure a fresh start by emptying or removing it at the
2355 start of the <prgn>binary</prgn> target.
2359 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2360 package, it adds an entry to <tt>debian/files</tt> for the
2361 <tt>.deb</tt> file that will be created when <prgn>dpkg-deb
2362 --build</prgn> is run for that binary package. So for most
2363 packages all that needs to be done with this file is to
2364 delete it in the <prgn>clean</prgn> target.
2368 If a package upload includes files besides the source
2369 package and any binary packages whose control files were
2370 made with <prgn>dpkg-gencontrol</prgn> then they should be
2371 placed in the parent of the package's top-level directory
2372 and <prgn>dpkg-distaddfile</prgn> should be called to add
2373 the file to the list in <tt>debian/files</tt>.</p>
2376 <sect id="restrictions"><heading>Restrictions on objects in source packages
2380 The source package may not contain any hard links
2383 This is not currently detected when building source
2384 packages, but only when extracting
2388 Hard links may be permitted at some point in the
2389 future, but would require a fair amount of
2392 </footnote>, device special files, sockets or setuid or
2396 Setgid directories are allowed.
2401 <sect id="descriptions"><heading>Descriptions of packages - the
2402 <tt>Description</tt> field </heading>
2405 The description is intended to describe the program to a user
2406 who has never met it before so that they know whether they
2407 want to install it. It should also give information about the
2408 significant dependencies and conflicts between this package
2409 and others, so that the user knows why these dependencies and
2410 conflicts have been declared.
2413 <sect1><heading>Notes about writing descriptions
2417 The single line synopsis should be kept brief - certainly
2418 under 80 characters.
2422 Do not include the package name in the synopsis line. The
2423 display software knows how to display this already, and you
2424 do not need to state it. Remember that in many situations
2425 the user may only see the synopsis line - make it as
2426 informative as you can.
2430 Do not try to continue the single line synopsis into the
2431 extended description. This will not work correctly when
2432 the full description is displayed, and makes no sense
2433 where only the summary (the single line synopsis) is
2438 The extended description should describe what the package
2439 does and how it relates to the rest of the system (in terms
2440 of, for example, which subsystem it is which part of).
2444 The description field needs to make sense to anyone, even
2445 people who have no idea about any of the things the
2449 The blurb that comes with a program in its
2450 announcements and/or <prgn>README</prgn> files is
2451 rarely suitable for use in a description. It is
2452 usually aimed at people who are already in the
2453 community where the package is used.
2459 Put important information first, both in the synopsis and
2460 extended description. Sometimes only the first part of the
2461 synopsis or of the description will be displayed. You can
2462 assume that there will usually be a way to see the whole
2463 extended description.
2467 You may include information about dependencies and so forth
2468 in the extended description, if you wish.
2472 Do not use tab characters. Their effect is not predictable.
2480 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2481 and installation procedure
2484 <sect><heading>Introduction to package maintainer scripts
2488 It is possible to supply scripts as part of a package which
2489 the package management system will run for you when your
2490 package is installed, upgraded or removed.
2494 These scripts should be the files <tt>preinst</tt>,
2495 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2496 control area of the package. They must be proper executable
2497 files; if they are scripts (which is recommended) they must
2498 start with the usual <tt>#!</tt> convention. They should be
2499 readable and executable by anyone, and not world-writable.
2503 The package management system looks at the exit status from
2504 these scripts. It is important that they exit with a
2505 non-zero status if there is an error, so that the package
2506 management system can stop its processing. For shell
2507 scripts this means that you <em>almost always</em> need to
2508 use <tt>set -e</tt> (this is usually true when writing shell
2509 scripts, in fact). It is also important, of course, that
2510 they don't exit with a non-zero status if everything went
2515 It is necessary for the error recovery procedures that the
2516 scripts be idempotent: i.e., invoking the same script several
2517 times in the same situation should do no harm. If the first
2518 call failed, or aborted half way through for some reason,
2519 the second call should merely do the things that were left
2520 undone the first time, if any, and exit with a success
2525 When a package is upgraded a combination of the scripts from
2526 the old and new packages is called in amongst the other
2527 steps of the upgrade procedure. If your scripts are going
2528 to be at all complicated you need to be aware of this, and
2529 may need to check the arguments to your scripts.
2533 Broadly speaking the <prgn>preinst</prgn> is called before
2534 (a particular version of) a package is installed, and the
2535 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2536 before (a version of) a package is removed and the
2537 <prgn>postrm</prgn> afterwards.
2540 <p> Programs called from maintainer scripts should not
2541 normally have a path prepended to them. Before installation
2542 is started the package management system checks to see if
2543 the programs <prgn>ldconfig</prgn>,
2544 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2545 and <prgn>update-rc.d</prgn> can be found via the
2546 <tt>PATH</tt> environment variable. Those programs, and any
2547 other program that one would expect to on the <tt>PATH</tt>,
2548 should thus be invoked without an absolute
2549 pathname. Maintainer scripts should also not reset the
2550 <tt>PATH</tt>, though they might choose to modify it by pre-
2551 or appending package-specific directories. These
2552 considerations really apply to all shell scripts.</p>
2555 <heading>Maintainer scripts Idempotency</heading>
2558 It is very important to make maintainer scripts
2562 That means that if it runs successfully or fails
2563 and then you call it again it doesn't bomb out,
2564 but just ensures that everything is the way it
2567 </footnote> This is so that if an error occurs, the
2568 user interrupts <prgn>dpkg</prgn> or some other
2569 unforeseen circumstance happens you don't leave the
2570 user with a badly-broken package.
2574 <heading>Controlling terminal for maintainer scripts</heading>
2577 The maintainer scripts are guaranteed to run with a
2578 controlling terminal and can interact with the user.
2579 If they need to prompt for passwords, do full-screen
2580 interaction or something similar you should do these
2581 things to and from <tt>/dev/tty</tt>, since
2582 <prgn>dpkg</prgn> will at some point redirect scripts'
2583 standard input and output so that it can log the
2584 installation process. Likewise, because these scripts
2585 may be executed with standard output redirected into a
2586 pipe for logging purposes, Perl scripts should set
2587 unbuffered output by setting <tt>$|=1</tt> so that the
2588 output is printed immediately rather than being
2593 Each script should return a zero exit status for
2594 success, or a nonzero one for failure.
2598 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2603 <list compact="compact">
2605 <p><var>new-preinst</var> <tt>install</tt></p>
2608 <p><var>new-preinst</var> <tt>install</tt>
2609 <var>old-version</var></p>
2612 <p><var>new-preinst</var> <tt>upgrade</tt>
2613 <var>old-version</var></p>
2616 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2617 <var>new-version</var>
2623 <list compact="compact">
2625 <p><var>postinst</var> <tt>configure</tt>
2626 <var>most-recently-configured-version</var></p>
2629 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2630 <var>new version</var></p>
2633 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2634 <tt>in-favour</tt> <var>package</var>
2635 <var>new-version</var></p>
2639 <var>deconfigured's-postinst</var>
2640 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2641 <var>failed-install-package</var> <var>version</var>
2642 <tt>removing</tt> <var>conflicting-package</var>
2649 <list compact="compact">
2651 <p><var>prerm</var> <tt>remove</tt></p>
2654 <p><var>old-prerm</var> <tt>upgrade</tt>
2655 <var>new-version</var></p>
2658 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2659 <var>old-version</var></p>
2662 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2663 <tt>in-favour</tt> <var>package</var>
2664 <var>new-version</var></p>
2668 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2669 <tt>in-favour</tt> <var>package-being-installed</var>
2670 <var>version</var> <tt>removing</tt>
2671 <var>conflicting-package</var>
2678 <list compact="compact">
2680 <p><var>postrm</var> <tt>remove</tt></p>
2683 <p><var>postrm</var> <tt>purge</tt></p>
2687 <var>old-postrm</var> <tt>upgrade</tt>
2688 <var>new-version</var></p>
2691 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2692 <var>old-version</var></p>
2695 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2698 <p><var>new-postrm</var> <tt>abort-install</tt>
2699 <var>old-version</var></p>
2702 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2703 <var>old-version</var></p>
2707 <var>disappearer's-postrm</var> <tt>disappear</tt>
2708 <var>overwriter</var>
2709 <var>overwriter-version</var></p></item>
2714 <sect id="unpackphase"><heading>Details of unpack phase of
2715 installation or upgrade
2719 The procedure on installation/upgrade/overwrite/disappear
2720 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2721 stage of <tt>dpkg --install</tt>) is as follows. In each
2722 case if an error occurs the actions are, in general, run
2723 backwards - this means that the maintainer scripts are run
2724 with different arguments in reverse order. These are the
2725 `error unwind' calls listed below.
2732 <p>If a version of the package is already
2735 <var>old-prerm</var> upgrade <var>new-version</var>
2740 If the script runs but exits with a non-zero
2741 exit status, <prgn>dpkg</prgn> will attempt:
2743 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2745 Error unwind, for both the above cases:
2747 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2755 <p>If a `conflicting' package is being removed at the same time:
2759 If any packages depended on that conflicting
2760 package and <tt>--auto-deconfigure</tt> is
2761 specified, call, for each such package:
2763 <var>deconfigured's-prerm</var> deconfigure \
2764 in-favour <var>package-being-installed</var> <var>version</var> \
2765 removing <var>conflicting-package</var> <var>version</var>
2769 <var>deconfigured's-postinst</var> abort-deconfigure \
2770 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2771 removing <var>conflicting-package</var> <var>version</var>
2773 The deconfigured packages are marked as
2774 requiring configuration, so that if
2775 <tt>--install</tt> is used they will be
2776 configured again if possible.</p>
2779 <p>To prepare for removal of the conflicting package, call:
2781 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2785 <var>conflictor's-postinst</var> abort-remove \
2786 in-favour <var>package</var> <var>new-version</var>
2797 <p>If the package is being upgraded, call:
2799 <var>new-preinst</var> upgrade <var>old-version</var>
2804 Otherwise, if the package had some configuration
2805 files from a previous version installed (i.e., it
2806 is in the `configuration files only' state):
2808 <var>new-preinst</var> install <var>old-version</var>
2812 <p>Otherwise (i.e., the package was completely purged):
2814 <var>new-preinst</var> install
2816 Error unwind versions, respectively:
2818 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2819 <var>new-postrm</var> abort-install <var>old-version</var>
2820 <var>new-postrm</var> abort-install
2830 The new package's files are unpacked, overwriting any
2831 that may be on the system already, for example any
2832 from the old version of the same package or from
2833 another package (backups of the old files are left
2834 around, and if anything goes wrong the package
2835 management system will attempt to put them back as
2836 part of the error unwind).
2840 It is an error for a package to contains files which
2841 are on the system in another package, unless
2842 <tt>Replaces</tt> is used (see <ref id="replaces">).
2843 Currently the <tt>--force-overwrite</tt> flag is
2844 enabled, downgrading it to a warning, but this may not
2849 It is a more serious error for a package to contain a
2850 plain file or other kind of non-directory where another
2851 package has a directory (again, unless
2852 <tt>Replaces</tt> is used). This error can be
2853 overridden if desired using
2854 <tt>--force-overwrite-dir</tt>, but this is not
2859 Packages which overwrite each other's files produce
2860 behavior which though deterministic is hard for the
2861 system administrator to understand. It can easily
2862 lead to `missing' programs if, for example, a package
2863 is installed which overwrites a file from another
2864 package, and is then removed again.
2867 Part of the problem is due to what is arguably a
2868 bug in <prgn>dpkg</prgn>.
2874 A directory will never be replaced by a symbolic links
2875 to a directory or vice versa; instead, the existing
2876 state (symlink or not) will be left alone and
2877 <prgn>dpkg</prgn> will follow the symlink if there is
2885 <p>If the package is being upgraded, call
2887 <var>old-postrm</var> upgrade <var>new-version</var>
2891 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2893 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2895 Error unwind, for both cases:
2897 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2903 This is the point of no return - if
2904 <prgn>dpkg</prgn> gets this far, it won't back off
2905 past this point if an error occurs. This will
2906 leave the package in a fairly bad state, which
2907 will require a successful re-installation to clear
2908 up, but it's when <prgn>dpkg</prgn> starts doing
2909 things that are irreversible.
2914 Any files which were in the old version of the package
2915 but not in the new are removed.</p>
2918 <p>The new file list replaces the old.</p>
2921 <p>The new maintainer scripts replace the old.</p>
2925 <p>Any packages all of whose files have been overwritten during the
2926 installation, and which aren't required for
2927 dependencies, are considered to have been removed.
2928 For each such package,
2931 <p><prgn>dpkg</prgn> calls:
2933 <var>disappearer's-postrm</var> disappear \
2934 <var>overwriter</var> <var>overwriter-version</var>
2939 <p>The package's maintainer scripts are removed.
2944 It is noted in the status database as being in a
2945 sane state, namely not installed (any conffiles
2946 it may have are ignored, rather than being
2947 removed by <prgn>dpkg</prgn>). Note that
2948 disappearing packages do not have their prerm
2949 called, because <prgn>dpkg</prgn> doesn't know
2950 in advance that the package is going to
2959 Any files in the package we're unpacking that are also
2960 listed in the file lists of other packages are removed
2961 from those lists. (This will lobotomize the file list
2962 of the `conflicting' package if there is one.)
2967 The backup files made during installation, above, are
2974 The new package's status is now sane, and recorded as
2975 `unpacked'. Here is another point of no return - if
2976 the conflicting package's removal fails we do not
2977 unwind the rest of the installation; the conflicting
2978 package is left in a half-removed limbo.
2983 If there was a conflicting package we go and do the
2984 removal actions (described below), starting with the
2985 removal of the conflicting package's files (any that
2986 are also in the package being installed have already
2987 been removed from the conflicting package's file list,
2988 and so do not get removed now).
2995 <sect><heading>Details of configuration</heading>
2998 When we configure a package (this happens with <tt>dpkg
2999 --install</tt>, or with <tt>--configure</tt>), we first
3000 update the conffiles and then call:
3002 <var>postinst</var> configure <var>most-recently-configured-version</var>
3007 No attempt is made to unwind after errors during
3012 If there is no most recently configured version
3013 <prgn>dpkg</prgn> will pass a null argument; older versions
3014 of dpkg may pass <tt><unknown></tt> (including the
3015 angle brackets) in this case. Even older ones do not pass a
3016 second argument at all, under any circumstances.
3020 <sect><heading>Details of removal and/or configuration purging
3028 <var>prerm</var> remove
3034 The package's files are removed (except conffiles).
3039 <var>postrm</var> remove
3043 <p>All the maintainer scripts except the postrm are removed.
3047 If we aren't purging the package we stop here. Note
3048 that packages which have no postrm and no conffiles
3049 are automatically purged when removed, as there is no
3050 difference except for the <prgn>dpkg</prgn>
3055 The conffiles and any backup files (<tt>~</tt>-files,
3056 <tt>#*#</tt> files, <tt>%</tt>-files,
3057 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3061 <var>postrm</var> purge
3065 <p>The package's file list is removed.</p>
3068 No attempt is made to unwind after errors during
3074 <chapt id="relationships"><heading>Declaring relationships between
3078 Packages can declare in their control file that they have
3079 certain relationships to other packages - for example, that
3080 they may not be installed at the same time as certain other
3081 packages, and/or that they depend on the presence of others,
3082 or that they should overwrite files in certain other packages
3087 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3088 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3089 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3093 Source packages may declare relationships to binary packages,
3094 saying that they require certain binary packages to be
3095 installed or absent at the time of building the package.
3099 This is done using the <tt>Build-Depends</tt>,
3100 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3101 <tt>Build-Conflicts-Indep</tt> control file fields.
3104 <sect id="depsyntax"><heading>Syntax of relationship fields
3108 These fields all have a uniform syntax. They are a list of
3109 package names separated by commas.
3113 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3114 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3115 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3116 control file fields of the package, which declare
3117 dependencies on other packages, the package names listed may
3118 also include lists of alternative package names, separated
3119 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3120 a case, the presence of any one of the alternative packages
3121 is installed, that part of the dependency is considered to
3126 All the fields except <tt>Provides</tt> may restrict their
3127 applicability to particular versions of each named package.
3128 This is done in parentheses after each individual package
3129 name; the parentheses should contain a relation from the
3130 list below followed by a version number, in the format
3131 described in <ref id="versions">.
3135 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3136 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3137 strictly earlier, earlier or equal, exactly equal, later or
3138 equal and strictly later, respectively. The forms
3139 <tt><</tt> and <tt>></tt> were used to mean
3140 earlier/later or equal, rather than strictly earlier/later,
3141 so they should not appear in new packages (though
3142 <prgn>dpkg</prgn> still supports them).
3146 Whitespace may appear at any point in the version
3147 specification, and must appear where it's necessary to
3148 disambiguate; it is not otherwise significant. For
3149 consistency and in case of future changes to
3150 <prgn>dpkg</prgn> it is recommended that a single space be
3151 used after a version relationship and before a version
3152 number; it is usual also to put a single space after each
3153 comma, on either side of each vertical bar, and before each
3162 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3167 All fields that specify build-time relationships
3168 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3169 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3170 may be restricted to a certain set of architectures. This
3171 is done in brackets after each individual package name and
3172 the optional version specification. The brackets enclose a
3173 list of Debian architecture names separated by whitespace.
3174 Exclamation marks may be prepended to each of the names.
3175 (It is not permitted for some names to be prepended with
3176 exclamation marks and others not.) If the current Debian
3177 host architecture is not in this list and there are no
3178 exclamation marks in the list, or it is in the list with a
3179 prepended exclamation mark, the package name and the
3180 associated version specification are ignored completely for
3181 the purposes of defining the relationships.
3188 Build-Depends-Indep: texinfo
3189 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3190 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3196 <heading>Binary Dependencies - <tt>Depends</tt>,
3197 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3198 <tt>Pre-Depends</tt>
3202 These five fields are used to declare a dependency
3203 relationship by one package on another. They appear in the
3204 depending package's control file.
3208 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3209 (discussed below) take effect <em>only</em> when a package
3210 is to be configured. They do not prevent a package being on
3211 the system in an unconfigured state while its dependencies
3212 are unsatisfied, and it is possible to replace a package
3213 whose dependencies are satisfied and which is properly
3214 installed with a different version whose dependencies are
3215 not and cannot be satisfied; when this is done the depending
3216 package will be left unconfigured (since attempts to
3217 configure it will give errors) and will not function
3222 For this reason packages in an installation run are usually
3223 all unpacked first and all configured later; this gives
3224 later versions of packages with dependencies on later
3225 versions of other packages the opportunity to have their
3226 dependencies satisfied.
3230 Thus <tt>Depends</tt> allows package maintainers to impose
3231 an order in which packages should be configured.
3233 <tag><tt>Depends</tt></tag>
3236 <p>This declares an absolute dependency.
3240 The <tt>Depends</tt> field should be used if the
3241 depended-on package is required for the depending
3242 package to provide a significant amount of
3246 <tag><tt>Recommends</tt></tag>
3248 <p>This declares a strong, but not absolute, dependency.
3252 The <tt>Recommends</tt> field should list packages
3253 that would be found together with this one in all but
3254 unusual installations.</p>
3257 <tag><tt>Suggests</tt></tag>
3261 This is used to declare that one package may be more
3262 useful with one or more others. Using this field
3263 tells the packaging system and the user that the
3264 listed packages are related to this one and can
3265 perhaps enhance its usefulness, but that installing
3266 this one without them is perfectly reasonable.
3270 <tag><tt>Enhances</tt></tag>
3273 This field is similar to Suggests but works in the
3274 opposite direction. It is used to declare that a
3275 package can enhance the functionality of another
3280 <tag><tt>Pre-Depends</tt></tag>
3284 This field is like <tt>Depends</tt>, except that it
3285 also forces <prgn>dpkg</prgn> to complete installation
3286 of the packages named before even starting the
3287 installation of the package which declares the
3292 <tt>Pre-Depends</tt> should be used sparingly,
3293 preferably only by packages whose premature upgrade or
3294 installation would hamper the ability of the system to
3295 continue with any upgrade that might be in progress.
3299 When the package declaring it is being configured, a
3300 <tt>Pre-Dependency</tt> will be considered satisfied
3301 only if the depending package has been correctly
3302 configured, just as if an ordinary <tt>Depends</tt>
3307 However, when a package declaring a Pre-dependency is
3308 being unpacked the predependency can be satisfied even
3309 if the depended-on package(s) are only unpacked or
3310 half-configured, provided that they have been
3311 configured correctly at some point in the past (and
3312 not removed or partially removed since). In this case
3313 both the previously-configured and currently unpacked
3314 or half-configured versions must satisfy any version
3315 clause in the <tt>Pre-Depends</tt> field.
3321 When selecting which level of dependency to use you should
3322 consider how important the depended-on package is to the
3323 functionality of the one declaring the dependency. Some
3324 packages are composed of components of varying degrees of
3325 importance. Such a package should list using
3326 <tt>Depends</tt> the package(s) which are required by the
3327 more important components. The other components'
3328 requirements may be mentioned as Suggestions or
3329 Recommendations, as appropriate to the components' relative
3334 <sect id="conflicts"><heading>Alternative binary packages -
3335 <tt>Conflicts</tt> and <tt>Replaces</tt>
3339 When one binary package declares a conflict with another
3340 <prgn>dpkg</prgn> will refuse to allow them to be installed
3341 on the system at the same time.
3345 If one package is to be installed, the other must be removed
3346 first - if the package being installed is marked as
3347 replacing (<ref id="replaces">) the one on the system, or
3348 the one on the system is marked as deselected, or both
3349 packages are marked <tt>Essential</tt>, then
3350 <prgn>dpkg</prgn> will automatically remove the package
3351 which is causing the conflict, otherwise it will halt the
3352 installation of the new package with an error. This
3353 mechanism specifically doesn't work when the installed
3354 package is <tt>Essential</tt>, but the new package is not.
3359 A package will not cause a conflict merely because its
3360 configuration files are still installed; it must be at least
3365 A special exception is made for packages which declare a
3366 conflict with their own package name, or with a virtual
3367 package which they provide (see below): this does not
3368 prevent their installation, and allows a package to conflict
3369 with others providing a replacement for it. You use this
3370 feature when you want the package in question to be the only
3371 package providing something.
3375 A <tt>Conflicts</tt> entry should almost never have an
3376 `earlier than' version clause. This would prevent
3377 <prgn>dpkg</prgn> from upgrading or installing the package
3378 which declared such a conflict until the upgrade or removal
3379 of the conflicted-with package had been completed.
3383 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3387 As well as the names of actual (`concrete') packages, the
3388 package relationship fields <tt>Depends</tt>,
3389 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3390 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3391 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3392 mention virtual packages.
3396 A virtual package is one which appears in the
3397 <tt>Provides</tt> control file field of another package.
3398 The effect is as if the package(s) which provide a
3399 particular virtual package name had been listed by name
3400 everywhere the virtual package name appears.
3404 If there are both a real and a virtual package of the same
3405 name then the dependency may be satisfied (or the conflict
3406 caused) by either the real package or any of the virtual
3407 packages which provide it. This is so that, for example,
3413 and someone else releases an xemacs package they can say
3417 </example> and all will work in the interim (until a purely
3418 virtual package name is decided on and the <tt>emacs</tt>
3419 and <tt>vm</tt> packages are changed to use it).
3423 If a dependency or a conflict has a version number attached
3424 then only real packages will be considered to see whether
3425 the relationship is satisfied (or the prohibition violated,
3426 for a conflict) - it is assumed that a real package which
3427 provides the virtual package is not of the `right' version.
3428 So, a <tt>Provides</tt> field may not contain version
3429 numbers, and the version number of the concrete package
3430 which provides a particular virtual package will not be
3431 looked at when considering a dependency on or conflict with
3432 the virtual package name.
3436 It is likely that the ability will be added in a future
3437 release of <prgn>dpkg</prgn> to specify a version number for
3438 each virtual package it provides. This feature is not yet
3439 present, however, and is expected to be used only
3444 If you want to specify which of a set of real packages should be the
3445 default to satisfy a particular dependency on a virtual package, you
3446 should list the real package as an alternative before the virtual.
3451 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3452 files and replacing packages
3456 The <tt>Replaces</tt> control file field has two purposes,
3457 which come into play in different situations.
3461 Virtual packages (<ref id="virtual">) are not considered
3462 when looking at a <tt>Replaces</tt> field - the packages
3463 declared as being replaced must be mentioned by their real
3467 <sect1><heading>Overwriting files in other packages
3471 Firstly, as mentioned before, it is usually an error for a
3472 package to contain files which are on the system in
3473 another package, though currently the
3474 <tt>--force-overwrite</tt> flag is enabled by default,
3475 downgrading the error to a warning,
3479 If the overwriting package declares that it replaces the
3480 one containing the file being overwritten then
3481 <prgn>dpkg</prgn> will proceed, and replace the file from
3482 the old package with that from the new. The file will no
3483 longer be listed as `owned' by the old package.
3487 If a package is completely replaced in this way, so that
3488 <prgn>dpkg</prgn> does not know of any files it still
3489 contains, it is considered to have disappeared. It will
3490 be marked as not wanted on the system (selected for
3491 removal) and not installed. Any conffiles details noted
3492 in the package will be ignored, as they will have been
3493 taken over by the replacing package(s). The package's
3494 <prgn>postrm</prgn> script will be run to allow the
3495 package to do any final cleanup required. See <ref
3496 id="mscriptsinstact">.
3500 In the future <prgn>dpkg</prgn> will discard files which
3501 would overwrite those from an already installed package
3502 which declares that it replaces the package being
3503 installed. This is so that you can install an older
3504 version of a package without problems.
3508 This usage of <tt>Replaces</tt> only takes effect when
3509 both packages are at least partially on the system at
3510 once, so that it can only happen if they do not conflict
3511 or if the conflict has been overridden.</p>
3514 <sect1><heading>Replacing whole packages, forcing their
3519 Secondly, <tt>Replaces</tt> allows the packaging system to
3520 resolve which package should be removed when there is a
3521 conflict - see <ref id="conflicts">. This usage only
3522 takes effect when the two packages <em>do</em> conflict,
3523 so that the two effects do not interfere with each other.
3528 <sect><heading>Relationships between source and binary packages -
3529 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3530 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3534 A source package may declare a dependency or a conflict on a
3535 binary package. This is done with the control file fields
3536 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3537 <tt>Build-Conflicts</tt>, and
3538 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3539 the dependencies and conflicts they define must be satisfied
3540 (as defined earlier for binary packages), when one of the
3541 targets in <tt>debian/rules</tt> that the particular field
3542 applies to is invoked.
3545 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3548 The <tt>Build-Depends</tt> and
3549 <tt>Build-Conflicts</tt> fields apply to the targets
3550 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3551 and <tt>binary-indep</tt>.
3554 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3557 The <tt>Build-Depends-Indep</tt> and
3558 <tt>Build-Conflicts-Indep</tt> fields apply to the
3559 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3570 <chapt id="conffiles"><heading>Configuration file handling
3574 <prgn>dpkg</prgn> can do a certain amount of automatic
3575 handling of package configuration files.
3579 Whether this mechanism is appropriate depends on a number of
3580 factors, but basically there are two approaches to any
3581 particular configuration file.
3585 The easy method is to ship a best-effort configuration in the
3586 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3587 handle updates. If the user is unlikely to want to edit the
3588 file, but you need them to be able to without losing their
3589 changes, and a new package with a changed version of the file
3590 is only released infrequently, this is a good approach.
3594 The hard method is to build the configuration file from
3595 scratch in the <prgn>postinst</prgn> script, and to take the
3596 responsibility for fixing any mistakes made in earlier
3597 versions of the package automatically. This will be
3598 appropriate if the file is likely to need to be different on
3603 <chapt id="sharedlibs"><heading>Shared libraries
3607 Packages containing shared libraries must be constructed with
3608 a little care to make sure that the shared library is always
3609 available. This is especially important for packages whose
3610 shared libraries are vitally important, such as the libc.
3614 Firstly, your package should install the shared libraries
3615 under their normal names. For example, the
3616 <prgn>libgdbm1</prgn> package should install
3617 <tt>libgdbm.so.1.7.3</tt> as
3618 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3619 renamed or re-linked by any prerm or postrm scripts;
3620 <prgn>dpkg</prgn> will take care of renaming things safely
3621 without affecting running programs, and attempts to interfere
3622 with this are likely to lead to problems.
3626 Secondly, your package should include the symlink that
3627 <prgn>ldconfig</prgn> would create for the shared libraries.
3628 For example, the <prgn>libgdbm1</prgn> package should include
3629 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3630 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3631 <prgn>ld.so</prgn> can find the library in between the time
3632 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3633 in the <prgn>postinst</prgn> script. Furthermore, older
3634 versions of the package management system required the library
3635 must be placed before the symlink pointing to it in the
3636 <tt>.deb</tt> file. This is so that by the time
3637 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3638 the previous symlink pointing at an older version of the
3639 library) the new shared library is already in place.
3640 Unfortunately, this was not not always possible, since it
3641 highly depends on the behavior of the file system. Some
3642 file systems (such as reiserfs) will reorder the files so it
3643 doesn't matter in what order you create them. Starting with
3644 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3645 files itself when building a package.
3649 Thirdly, the development package should contain a symlink for
3650 the shared library without a version number. For example, the
3651 <tt>libgdbm1-dev</tt> package should include a symlink from
3652 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3653 symlink is needed by <prgn>ld</prgn> when compiling packages
3654 as it will only look for <tt>libgdm.so</tt> and
3655 <tt>libgdm.a</tt> when compiling dynamically or statically,
3660 Any package installing shared libraries in a directory that's listed
3661 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3662 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3663 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3664 script if and only if the first argument is `configure'. However, it
3665 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3666 scripts in the case where the package is being upgraded (see <ref
3667 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3668 that <prgn>dpkg</prgn> uses for the files while it is
3669 installing them and will make the shared library links point
3670 to them, just before <prgn>dpkg</prgn> continues the
3671 installation and removes the links!
3674 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3678 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3679 required when your package provides shared libraries.
3683 Each line is of the form:
3685 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3690 <var>library-name</var> is the name of the shared library,
3691 for example <tt>libc5</tt>.
3695 <var>version-or-soname</var> is the soname of the library -
3696 i.e., the thing that must exactly match for the library to be
3697 recognized by <prgn>ld.so</prgn>. Usually this is the major
3698 version number of the library.
3702 <var>dependencies</var> has the same syntax as a dependency
3703 field in a binary package control file. It should give
3704 details of which package(s) are required to satisfy a binary
3705 built against the version of the library contained in the
3706 package. See <ref id="depsyntax">.
3710 For example, if the package <tt>foo</tt> contains
3711 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3712 <tt>libfoo.so.1</tt>, and the first version of the package
3713 which contained a minor number of at least <tt>2.3</tt> was
3714 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3717 libfoo 1 foo (>= 1.2.3-1)
3722 The version-specific dependency is to avoid warnings from
3723 <prgn>ld.so</prgn> about using older shared libraries with
3727 <sect><heading>Further Technical information on
3728 <tt>shlibs</tt></heading>
3730 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3734 The <tt>debian/shlibs</tt> file provides a way of checking
3735 for shared library dependencies on packaged binaries.
3736 They are intended to be used by package maintainers to
3737 make their lives easier.
3741 Other <tt>shlibs</tt> files that exist on a Debian system are
3743 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3744 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3745 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3746 <item> <p><tt>debian/shlibs.local</tt></p></item>
3748 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3749 creating a binary package.</p>
3752 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3756 <prgn>dpkg-shlibdeps</prgn>
3757 determines the shared libraries directly
3760 It used to do this by calling <prgn>ldd</prgn>, but it
3761 now calls <prgn>objdump</prgn> to do this. This
3762 requires a couple of changes in the way that packages
3766 A binary <tt>foo</tt> directly uses a library
3767 <tt>libbar</tt> if it is linked with that
3768 library. Other libraries that are needed by
3769 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3770 and the dynamic linker will load them automatically
3771 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3772 lists all of the libraries used, both directly and
3773 indirectly; but <prgn>objdump</prgn> only lists the
3774 directly linked libraries. A package only needs to
3775 depend on the libraries it is directly linked to,
3776 since the dependencies for those libraries should
3777 automatically pull in the other libraries.
3780 This change does mean a change in the way packages are
3781 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3782 only run on binaries. But since we will now rely on the
3783 libraries depending on the libraries they themselves
3784 need, the packages containing those libraries will
3785 need to run <prgn>dpkg-shlibdeps</prgn> on the
3789 A good example where this would help us is the current
3790 mess with multiple version of the <tt>mesa</tt>
3791 library. With the <prgn>ldd</prgn>-based system, every
3792 package that uses <tt>mesa</tt> needs to add a
3793 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3794 to handle the glide <tt>mesa</tt> variant. With an
3795 <prgn>objdump</prgn>-based system this isn't necessary
3796 anymore and would have saved everyone a lot of work.
3799 Another example: we could update <tt>libimlib</tt>
3800 with a new version that supports a new graphics format
3801 called dgf. If we use the old <prgn>ldd</prgn> method,
3802 every package that uses <tt>libimlib</tt> would need
3803 to be recompiled so it would also depend on
3804 <tt>libdgf</tt> or it wouldn't run due to missing
3805 symbols. However with the new system, packages using
3806 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3807 having the dependency on <tt>libdgf</tt> and wouldn't
3811 used by the compiled binaries and libraries passed through
3812 on its command line.
3816 For each shared library linked to,
3817 <prgn>dpkg-shlibdeps</prgn> needs to know
3818 <list compact="compact">
3819 <item><p>the package containing the library, and</p></item>
3820 <item><p>the library version number,</p></item>
3822 and it scans the following files in this order:
3823 <enumlist compact="compact">
3824 <item><p><tt>debian/shlibs.local</tt></p></item>
3825 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3826 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3827 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3832 <sect1><heading><em>Who</em> maintains the various
3833 <tt>shlibs</tt> files?
3837 <list compact="compact">
3839 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3844 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3845 - the maintainer of each package</p>
3849 <tt>/etc/dpkg/shlibs.override</tt> - the local
3850 system administrator</p>
3853 <p><tt>debian/shlibs.local</tt> - the maintainer of
3858 The <tt>shlibs.default</tt> file is managed by
3859 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3860 that are provided by <prgn>dpkg</prgn> are just there to
3861 fix things until the shared library packages all have
3862 <tt>shlibs</tt> files.
3866 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3867 the <tt>shlibs</tt> files
3870 <sect2><heading>If your package doesn't provide a shared
3875 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3876 <tt>debian/rules</tt> file. If your package contains
3877 only binaries (e.g. no scripts) use:
3879 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3881 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3882 done. If it does complain you might need to create your
3883 own <tt>debian/shlibs.local</tt> file.</p>
3886 <sect2><heading>If your package provides a shared library
3890 Create a <tt>debian/shlibs</tt> file and let
3891 <tt>debian/rules</tt> install it in the control area:
3893 install -m644 debian/shlibs debian/tmp/DEBIAN
3895 If your package contains additional binaries see above.
3900 <sect1><heading><em>How</em> to write
3901 <tt>debian/shlibs.local</tt>
3905 This file is intended only as a <em>temporary</em> fix if
3906 your binaries depend on a library which doesn't provide
3907 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3911 Let's assume you are packaging a binary <tt>foo</tt>. Your
3912 output in building the package might look like this.
3915 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3916 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3917 libc.so.6 => /lib/libc.so.6 (0x40114000)
3918 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3920 And when you ran <prgn>dpkg-shlibdeps</prgn>
3922 $ dpkg-shlibdeps -O foo
3923 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3924 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3925 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3927 The <prgn>foo</prgn> binary depends on the
3928 <prgn>libbar</prgn> shared library, but no package seems
3929 to provide a <tt>*.shlibs</tt> file in
3930 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3936 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3937 bar1: /usr/X11R6/lib/libbar.so.1.0
3938 $ dpkg -s bar1 | grep Version
3941 This tells us that the <prgn>bar1</prgn> package, version
3942 1.0-1 is the one we are using. Now we can create our own
3943 <tt>debian/shlibs.local</tt> to temporarily fix the above
3944 problem. Include the following line into your
3945 <tt>debian/shlibs.local</tt> file.
3947 libbar 1 bar1 (>= 1.0-1)
3949 Now your package build should work. As soon as the
3950 maintainer of <prgn>libbar1</prgn> provides a
3951 <tt>shlibs</tt> file, you can remove your
3952 <tt>debian/shlibs.local</tt> file.
3958 <chapt><heading>The Operating System</heading>
3962 <heading>File system hierarchy</heading>
3966 <heading>Linux File system Structure</heading>
3969 The location of all installed files and directories must
3970 comply with the Linux File system Hierarchy Standard
3971 (FHS). The latest version of this document can be found
3972 alongside this manual or on
3973 <url id="http://www.pathname.com/fhs/">.
3974 Specific questions about following the standard may be
3975 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3976 Quinlan, the FHS coordinator, at
3977 <email>quinlan@pathname.com</email>.</p></sect1>
3981 <heading>Site-specific programs</heading>
3984 As mandated by the FHS, packages must not place any
3985 files in <tt>/usr/local</tt>, either by putting them in
3986 the file system archive to be unpacked by <prgn>dpkg</prgn>
3987 or by manipulating them in their maintainer scripts.</p>
3990 However, the package may create empty directories below
3991 <tt>/usr/local</tt> so that the system administrator knows
3992 where to place site-specific files. These directories
3993 should be removed on package removal if they are
3997 Note, that this applies only to directories <em>below</em>
3998 <tt>/usr/local</tt>, not <em>in</em>
3999 <tt>/usr/local</tt>. Packages must not create sub-directories
4000 in the directory <tt>/usr/local</tt> itself, except those listed in
4001 FHS, section 4.5. However, you may create directories
4002 below them as you wish. You must not remove any of the
4003 directories listed in 4.5, even if you created them.</p>
4006 Since <tt>/usr/local</tt> can be mounted read-only from a
4007 remote server, these directories must be created and
4008 removed by the <tt>postinst</tt> and <tt>prerm</tt>
4009 maintainer scripts. These scripts must not fail if either
4010 of these operations fail. (In the future, it will be
4011 possible to tell <prgn>dpkg</prgn> not to unpack files
4012 matching certain patterns, so that the directories can be
4013 included in the <tt>.deb</tt> packages and system
4014 administrators who do not wish these directories in
4015 /usr/local do not need to have them.)</p>
4018 For example, the <prgn>emacs</prgn> package will contain
4020 mkdir -p /usr/local/lib/emacs/site-lisp || true
4022 in the <tt>postinst</tt> script, and
4024 rmdir /usr/local/lib/emacs/site-lisp || true
4025 rmdir /usr/local/lib/emacs || true
4027 in the <tt>prerm</tt> script.</p>
4030 If you do create a directory in <tt>/usr/local</tt> for
4031 local additions to a package, you should ensure that
4032 settings in <tt>/usr/local</tt> take precedence over the
4033 equivalents in <tt>/usr</tt>.</p>
4036 However, because '/usr/local' and its contents are for
4037 exclusive use of the local administrator, a package must
4038 not rely on the presence or absence of files or
4039 directories in '/usr/local' for normal operation.</p>
4042 The <tt>/usr/local</tt> directory itself and all the
4043 subdirectories created by the package should (by default) have
4044 permissions 2775 (group-writable and set-group-id) and be
4045 owned by <tt>root.staff</tt>.</p>
4050 <heading>Users and groups</heading>
4053 The Debian system can be configured to use either plain or
4054 shadow passwords.</p>
4057 Some user ids (UIDs) and group ids (GIDs) are reserved
4058 globally for use by certain packages. Because some packages
4059 need to include files which are owned by these users or
4060 groups, or need the ids compiled into binaries, these ids
4061 must be used on any Debian system only for the purpose for
4062 which they are allocated. This is a serious restriction, and
4063 we should avoid getting in the way of local administration
4064 policies. In particular, many sites allocate users and/or
4065 local system groups starting at 100.</p>
4068 Apart from this we should have dynamically allocated ids,
4069 which should by default be arranged in some sensible
4070 order--but the behavior should be configurable.</p>
4073 Packages other than <tt>base-passwd</tt> must not modify
4074 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4075 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4078 The UID and GID ranges are as follows:
4083 Globally allocated by the Debian project, the
4084 same on every Debian system. These ids will appear in
4085 the <tt>passwd</tt> and <tt>group</tt> files of all
4086 Debian systems, new ids in this range being added
4087 automatically as the <tt>base-passwd</tt> package is
4091 Packages which need a single statically allocated uid
4092 or gid should use one of these; their maintainers
4093 should ask the <tt>base-passwd</tt> maintainer for
4100 Dynamically allocated system users and groups.
4101 Packages which need a user or group, but can have this
4102 user or group allocated dynamically and differently on
4103 each system, should use `<tt>adduser --system</tt>' to
4104 create the group and/or user. <prgn>adduser</prgn>
4105 will check for the existence of the user or group, and
4106 if necessary choose an unused id based on the ranges
4107 specified in <tt>adduser.conf</tt>.</p></item>
4110 <tag>1000-29999:</tag>
4113 Dynamically allocated user accounts. By default
4114 <prgn>adduser</prgn> will choose UIDs and GIDs for
4115 user accounts in this range, though
4116 <tt>adduser.conf</tt> may be used to modify this
4120 <tag>30000-59999:</tag>
4122 <p>Reserved.</p></item>
4125 <tag>60000-64999:</tag>
4128 Globally allocated by the Debian project, but only
4129 created on demand. The ids are allocated centrally and
4130 statically, but the actual accounts are only created
4131 on users' systems on demand.</p>
4134 These ids are for packages which are obscure or which
4135 require many statically-allocated ids. These packages
4136 should check for and create the accounts in
4137 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4138 <prgn>adduser</prgn> if it has this facility) if
4139 necessary. Packages which are likely to require
4140 further allocations should have a `hole' left after
4141 them in the allocation, to give them room to
4145 <tag>65000-65533:</tag>
4147 <p>Reserved.</p></item>
4152 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4153 to the group `<tt>nogroup</tt>.'</p></item>
4159 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4160 because it is the error return sentinel value.</p>
4165 <sect id="sysvinit">
4166 <heading>System run levels</heading>
4169 <sect1 id="/etc/init.d">
4170 <heading>Introduction</heading>
4173 The <tt>/etc/init.d</tt> directory contains the scripts
4174 executed by <prgn>init</prgn> at boot time and when init
4175 state (or `runlevel') is changed (see <manref name="init"
4179 There are at least two different, yet functionally
4180 equivalent, ways of handling these scripts. For the sake
4181 of simplicity, this document describes only the symbolic
4182 link method. However, it must not be assumed by maintainer
4183 scripts that this method is being used, and any automated
4184 manipulation of the various runlevel behaviours by
4185 maintainer scripts must be performed using `update-rc.d'
4186 as described below and not by manually installing or
4187 removing symlinks. For information on the
4188 implementation details of the other method, implemented in
4189 the <tt>file-rc</tt> package, please refer to the
4190 documentation of that package.</p>
4193 These scripts are referenced by symbolic links in
4194 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4195 changing runlevels, <prgn>init</prgn> looks in the
4196 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4197 it should execute, where <var>n</var> is the runlevel that
4198 is being changed to, or `S' for the boot-up scripts.</p>
4201 The names of the links all have the form
4202 <tt>S<var>mm</var><var>script</var></tt> or
4203 <tt>K<var>mm</var><var>script</var></tt> where
4204 <var>mm</var> is a two-digit number and <var>script</var>
4205 is the name of the script (this should be the same as the
4206 name of the actual script in <tt>/etc/init.d</tt>.</p>
4209 When <prgn>init</prgn> changes runlevel first the targets
4210 of the links whose names starting with a <tt>K</tt> are
4211 executed, each with the single argument <tt>stop</tt>,
4212 followed by the scripts prefixed with an <tt>S</tt>, each
4213 with the single argument <tt>start</tt>. The <tt>K</tt>
4214 links are responsible for killing services and the
4215 <tt>S</tt> link for starting services upon entering the
4219 For example, if we are changing from runlevel 2 to
4220 runlevel 3, init will first execute all of the <tt>K</tt>
4221 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4222 all of the <tt>S</tt> prefixed scripts. The links
4223 starting with <tt>K</tt> will cause the referred-to file
4224 to be executed with an argument of <tt>stop</tt>, and the
4225 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4228 The two-digit number <var>mm</var> is used to decide which
4229 order to start and stop things in--low-numbered links have
4230 their scripts run first. For example, the <tt>K20</tt>
4231 scripts will be executed before the <tt>K30</tt> scripts.
4232 This is used when a certain service must be started before
4233 another. For example, the name server <prgn>bind</prgn>
4234 might need to be started before the news server
4235 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4236 access lists. In this case, the script that starts
4237 <prgn>bind</prgn> would have a lower number than the
4238 script that starts <prgn>inn</prgn> so that it runs first:
4247 <heading>Writing the scripts</heading>
4250 Packages that include daemons for system services should
4251 place scripts in <tt>/etc/init.d</tt> to start or stop
4252 services at boot time or during a change of runlevel.
4253 These scripts should be named
4254 <tt>/etc/init.d/<var>package</var></tt>, and they should
4255 accept one argument, saying what to do:
4258 <tag><tt>start</tt></tag>
4259 <item><p>start the service,</p></item>
4261 <tag><tt>stop</tt></tag>
4262 <item><p>stop the service,</p></item>
4264 <tag><tt>restart</tt></tag>
4265 <item><p>stop and restart the service,</p></item>
4267 <tag><tt>reload</tt></tag>
4268 <item><p>cause the configuration of the service to be
4269 reloaded without actually stopping and restarting
4270 the service,</p></item>
4272 <tag><tt>force-reload</tt></tag> <item><p>cause the
4273 configuration to be reloaded if the service supports
4274 this, otherwise restart the service.</p></item>
4277 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4278 <tt>force-reload</tt> options should be supported by all
4279 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4280 option is optional.</p>
4283 The <tt>init.d</tt> scripts should ensure that they will
4284 behave sensibly if invoked with <tt>start</tt> when the
4285 service is already running, or with <tt>stop</tt> when it
4286 isn't, and that they don't kill unfortunately-named user
4287 processes. The best way to achieve this is usually to use
4288 <prgn>start-stop-daemon</prgn>.</p>
4291 If a service reloads its configuration automatically (as
4292 in the case of <prgn>cron</prgn>, for example), the
4293 <tt>reload</tt> option of the <tt>init.d</tt> script
4294 should behave as if the configuration has been reloaded
4298 These scripts should not fail obscurely when the
4299 configuration files remain but the package has been
4300 removed, as configuration files remain on the system after
4301 the package has been removed. Only when <prgn>dpkg</prgn>
4302 is executed with the <tt>--purge</tt> option will
4303 configuration files be removed. In particular, the init
4304 script itself is usually a configuration file (see
4305 <ref id="init.d notes">), and will remain on the system if
4306 the package is removed but not purged. Therefore, you
4307 should include a <tt>test</tt> statement at the top of the
4310 test -f <var>program-executed-later-in-script</var> || exit 0
4314 Often there are some values in the `<tt>init.d</tt>'
4315 scripts that a system administrator will frequently want
4316 to change. While the scripts are frequently conffiles,
4317 modifying them requires that the administrator merge in
4318 their changes each time the package is upgraded and the
4319 conffile changes. To ease the burden on the system
4320 administrator, such configurable values should not be
4321 placed directly in the script. Instead, they should be
4322 placed in a file in `<tt>/etc/default</tt>', which
4323 typically will have the same base name as the
4324 `<tt>init.d</tt>' script. This extra file can be sourced
4325 by the script when the script runs. It must contain only
4326 variable settings and comments.
4330 To ensure that vital configurable values are always
4331 available, the `<tt>init.d</tt>' script should set default
4332 values for each of the shell variables it uses before
4333 sourcing the <tt>/etc/default/</tt> file. Also, since the
4334 `<tt>/etc/default/</tt>' file is often a conffile, the
4335 `<tt>init.d</tt>' script must behave sensibly without
4336 failing if it is deleted.
4342 <heading>Managing the links</heading>
4345 The program <prgn>update-rc.d</prgn> is provided to make
4346 it easier for package maintainers to arrange for the
4347 proper creation and removal of
4348 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4349 functional equivalent if another method is being used.
4350 This may be used by maintainers in their packages'
4351 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4354 You must use this script to make changes to
4355 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4356 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4357 in the actual archive or manually create or remove the
4358 symbolic links in maintainer scripts. (The latter will
4359 fail if an alternative method of maintaining runlevel
4360 information is being used.)</p>
4363 By default <prgn>update-rc.d</prgn> will start services in
4364 each of the multi-user state runlevels (2, 3, 4, and 5)
4365 and stop them in the halt runlevel (0), the single-user
4366 runlevel (1) and the reboot runlevel (6). The system
4367 administrator will have the opportunity to customize
4368 runlevels by either running <prgn>update-rc.d</prgn>, by
4369 simply adding, moving, or removing the symbolic links in
4370 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4371 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4372 <tt>file-rc</tt> method is being used.</p>
4375 To get the default behavior for your package, put in your
4376 <tt>postinst</tt> script
4378 update-rc.d <var>package</var> defaults >/dev/null
4380 and in your <tt>postrm</tt>
4382 if [ purge = "$1" ]; then
4383 update-rc.d <var>package</var> remove >/dev/null
4388 This will use a default sequence number of 20. If it does
4389 not matter when or in which order the script is run, use
4390 this default. If it does, then you should talk to the
4391 maintainer of the <prgn>sysvinit</prgn> package or post to
4392 <tt>debian-devel</tt>, and they will help you choose a
4396 For more information about using <tt>update-rc.d</tt>,
4397 please consult its manpage <manref name="update-rc.d"
4398 section="8">.</p></sect1>
4402 <heading>Boot-time initialization</heading>
4405 There used to be another directory, <tt>/etc/rc.boot</tt>,
4406 which contained scripts which were run once per machine
4407 boot. This has been deprecated in favour of links from
4408 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4409 described in <ref id="/etc/init.d">. Packages must not
4410 place files in <tt>/etc/rc.boot</tt>.</p>
4412 <sect1 id="init.d notes">
4413 <heading>Notes</heading>
4416 <em>Do not</em> include the
4417 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4418 <tt>.deb</tt> file system archive! <em>This will cause
4419 problems!</em> You must create them with
4420 <prgn>update-rc.d</prgn>, as above.</p>
4423 <em>Do not</em> include the
4424 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4425 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4426 problems!</em> You should, however, treat the
4427 <tt>/etc/init.d</tt> scripts as configuration files,
4428 either by marking them as conffiles or managing them
4429 correctly in the maintainer scripts (see
4430 <ref id="config files">). (This is important since we want
4431 to give the local system administrator the chance to adapt
4432 the scripts to the local system--e.g., to disable a
4433 service without de-installing the package, or to specify
4434 some special command line options when starting a
4435 service--while making sure her changes aren't lost during
4436 the next package upgrade.)</p>
4440 <heading>Example</heading>
4443 The <prgn>bind</prgn> DNS (nameserver) package wants to
4444 make sure that the nameserver is running in multiuser
4445 runlevels, and is properly shut down with the system. It
4446 puts a script in <tt>/etc/init.d</tt>, naming the script
4447 appropriately <tt>bind</tt>. As you can see, the script
4448 interprets the argument <tt>reload</tt> to send the
4449 nameserver a <tt>HUP</tt> signal (causing it to reload its
4450 configuration); this way the user can say
4451 <tt>/etc/init.d/bind reload</tt> to reload the name
4452 server. The script has one configurable value, which can
4453 be used to pass parameters to the named program at
4461 # Original version by Robert Leslie
4462 # <rob@mars.org>, edited by iwj and cs
4464 test -x /usr/sbin/named || exit 0
4466 # Source defaults file.
4468 if [ -f /etc/default/bind ]; then
4475 echo -n "Starting domain name service: named"
4476 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4481 echo -n "Stopping domain name service: named"
4482 start-stop-daemon --stop --quiet \
4483 --pidfile /var/run/named.pid --exec /usr/sbin/named
4487 echo -n "Restarting domain name service: named"
4488 start-stop-daemon --stop --quiet \
4489 --pidfile /var/run/named.pid --exec /usr/sbin/named
4490 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4494 force-reload|reload)
4495 echo -n "Reloading configuration of domain name service: named"
4496 start-stop-daemon --stop --signal 1 --quiet \
4497 --pidfile /var/run/named.pid --exec /usr/sbin/named
4501 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4511 Complementing the above init script is a file
4512 '<tt>/etc/default/bind</tt>', which contains configurable
4513 parameters used by the script.
4517 # Specified parameters to pass to named. See named(8).
4518 # You may uncomment the following line, and edit to taste.
4524 Another example on which to base your <tt>/etc/init.d</tt>
4525 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4528 If this package is happy with the default setup from
4529 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4530 and having named running in all runlevels, it can say in
4531 its <tt>postinst</tt>:
4533 update-rc.d bind defaults >/dev/null
4535 And in its <tt>postrm</tt>, to remove the links when the
4538 if [ purge = "$1" ]; then
4539 update-rc.d bind remove >/dev/null
4545 <heading>Cron jobs</heading>
4548 Packages must not modify the configuration file
4549 <tt>/etc/crontab</tt>, and they must not modify the files in
4550 <tt>/var/spool/cron/crontabs</tt>.</p>
4553 If a package wants to install a job that has to be executed
4554 via cron, it should place a file with the name of the
4555 package in one of the following directories:
4561 As these directory names imply, the files within them are
4562 executed on a daily, weekly, or monthly basis,
4563 respectively. The exact times are listed in
4564 <tt>/etc/crontab</tt>.</p>
4567 All files installed in any of these directories must be
4568 scripts (shell scripts, Perl scripts, etc.) so that they can
4569 easily be modified by the local system administrator. In
4570 addition, they should be treated as configuration files.</p>
4573 If a certain job has to be executed more frequently than
4574 daily, the package should install a file
4575 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4576 the same syntax as <tt>/etc/crontab</tt> and is processed by
4577 <prgn>cron</prgn> automatically. The file must also be
4578 treated as a configuration file. (Note, that entries in the
4579 <tt>/etc/cron.d</tt> directory are not handled by
4580 <prgn>anacron</prgn>. Thus, you should only use this
4581 directory for jobs which may be skipped if the system is not
4585 The scripts or crontab entries in these directories should
4586 check if all necessary programs are installed before they
4587 try to execute them. Otherwise, problems will arise when a
4588 package was removed but not purged since configuration files
4589 are kept on the system in this situation.</p>
4593 <heading>Console messages</heading>
4596 This section describes different formats for messages
4597 written to standard output by the <tt>/etc/init.d</tt>
4598 scripts. The intent is to improve the consistency of
4599 Debian's startup and shutdown look and feel.</p>
4602 Please look very careful at the details. We want to get the
4603 messages to look exactly the same way concerning spaces,
4604 punctuation, and case of letters.</p>
4607 Here is a list of overall rules that you should use when you
4608 create output messages. They can be useful if you have a
4609 non-standard message that isn't covered in the sections
4616 Every message should cover one line, start with a
4617 capital letter and end with a period `.'.</p></item>
4622 If you want to express that the computer is working on
4623 something (performing a specific task, not starting or
4624 stopping a program), we use an ``ellipsis'', namely
4625 three dots `...'. Note that we don't insert spaces in
4626 front of or behind the dots. If the task has been
4627 completed we write `done.' and a line feed.</p></item>
4632 Design your messages as if the computer is telling you
4633 what he is doing (let him be polite :-) but don't
4634 mention ``him'' directly. For example, if you think
4637 I'm starting network daemons: nfsd mountd.
4641 Starting network daemons: nfsd mountd.
4642 </example></p></item>
4646 The following formats should be used</p>
4651 <p>when daemons get started.</p>
4654 Use this format if your script starts one or more
4655 daemons. The output should look like this (a single
4656 line, no leading spaces):
4658 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4660 The <description> should describe the subsystem
4661 the daemon or set of daemons are part of, while
4662 <daemon-1> up to <daemon-n> denote each
4663 daemon's name (typically the file name of the
4667 For example, the output of /etc/init.d/lpd would look like:
4669 Starting printer spooler: lpd.
4673 This can be achieved by saying
4675 echo -n "Starting printer spooler: lpd"
4676 start-stop-daemon --start --quiet lpd
4679 in the script. If you have more than one daemon to
4680 start, you should do the following:
4682 echo -n "Starting remote file system services:"
4683 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4684 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4685 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4688 This makes it possible for the user to see what takes
4689 so long and when the final daemon has been
4690 started. You should be careful where to put spaces: In the
4691 example above the system administrator can easily
4692 comment out a line if he don't wants to start a
4693 specific daemon, while the displayed message still
4694 looks good.</p></item>
4698 <p>when something needs to be configured.</p>
4701 If you have to set up different parameters of the
4702 system upon boot up, you should use this format:
4704 Setting <parameter> to `<value>'.
4708 You can use the following echo statement to get the quotes right:
4710 echo "Setting DNS domainname to \`"value"'."
4714 Note that the left quotation mark (`) is different
4715 from the right (').</p></item>
4718 <p>when a daemon is stopped.</p>
4721 When you stop a daemon you should issue a message
4722 similar to the startup message, except that `Starting'
4723 is replaced with `Stopping'.</p>
4726 So stopping the printer daemon will like like this:
4728 Stopping printer spooler: lpd.
4729 </example></p></item>
4732 <p>when something is executed.</p>
4735 There are several examples where you have to run a
4736 program at system startup or shutdown to perform a
4737 specific task. For example, setting the system's clock
4738 via `netdate' or killing all processes when the system
4739 comes down. Your message should like this:
4741 Doing something very useful...done.
4743 You should print the `done.' right after the job has been completed,
4744 so that the user gets informed why he has to wait. You can get this
4747 echo -n "Doing something very useful..."
4751 in your script.</p></item>
4754 <p>when the configuration is reloaded.</p>
4757 When a daemon is forced to reload its configuration
4758 files you should use the following format:
4760 Reloading <daemon's-name> configuration...done.
4761 </example></p></item>
4764 <p>when none of the above rules apply.</p>
4767 If you have to print a message that doesn't fit into
4768 the styles described above, you can use something
4769 appropriate, but please have a look at the overall
4770 rules listed above.</p></item>
4775 <heading>Menus</heading>
4778 Menu entries should follow the current menu policy as
4779 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4780 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4781 or your local mirror. In addition, it is included in the
4782 <tt>debian-policy</tt> package.
4786 The Debian <tt>menu</tt> packages provides a unique
4787 interface between packages providing applications and
4788 documents, and <em>menu programs</em> (either X window
4789 managers or text-based menu programs as
4790 <prgn>pdmenu</prgn>).</p>
4793 All packages that provide applications that need not be
4794 passed any special command line arguments for normal
4795 operation should register a menu entry for those
4796 applications, so that users of the <tt>menu</tt> package
4797 will automatically get menu entries in their window
4798 managers, as well in shells like <tt>pdmenu</tt>.</p>
4801 Please refer to the <em>Debian Menu System</em> document
4802 that comes with the <tt>menu</tt> package for information
4803 about how to register your applications and web
4809 <heading>Multimedia handlers</heading>
4812 Packages which provide the ability to view/show/play,
4813 compose, edit or print MIME types should register themselves
4814 as such following the current MIME support policy as defined
4815 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4816 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4817 or your local mirror. In addition, it is included in the
4818 <tt>debian-policy</tt> package.
4822 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4823 mechanism for encoding files and data streams and providing
4824 meta-information about them, in particular their type (e.g.
4825 audio or video) and format (e.g. PNG, HTML, MP3).
4829 Registration of MIME type handlers allows programs like mail
4830 user agents and web browsers to to invoke these handlers to
4831 view, edit or display MIME types they don't support
4837 <heading>Keyboard configuration</heading>
4840 To achieve a consistent keyboard configuration (i.e., all
4841 applications interpret a keyboard event the same way) all
4842 programs in the Debian distribution must be configured to
4843 comply with the following guidelines.</p>
4846 Here is a list that contains certain keys and their interpretation:
4849 <tag><tt><--</tt></tag>
4850 <item><p>delete the character to the left of the cursor</p></item>
4852 <tag><tt>Delete</tt></tag>
4853 <item><p>delete the character to the right of the cursor</p></item>
4855 <tag><tt>Control+H</tt></tag>
4856 <item><p>emacs: the help prefix</p></item>
4859 The interpretation of any keyboard events should be independent
4860 of the terminal that's used, be it a virtual console, an X
4861 terminal emulator, an rlogin/telnet session, etc.</p>
4864 The following list explains how the different programs
4865 should be set up to achieve this:</p>
4868 <list compact="compact">
4869 <item><p>`<tt><--</tt>' generates KB_Backspace in
4872 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4876 X translations are set up to make KB_Backspace
4877 generate ASCII DEL, and to make KB_Delete generate
4878 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4879 the `delete character' key). This must be done by
4880 loading the resources using xrdb on all local X
4881 displays, not using the application defaults, so that
4882 the translation resources used correspond to the
4883 xmodmap settings.</p></item>
4887 The Linux console is configured to make
4888 `<tt><--</tt>' generate DEL, and `Delete' generate
4889 <tt>ESC [ 3 ~</tt> (this is the case at the
4893 X applications are configured so that Backspace
4894 deletes left, and Delete deletes right. Motif
4895 applications already work like this.</p></item>
4897 <item><p>stty erase <tt>^?</tt> .</p></item>
4900 The `xterm' terminfo entry should have <tt>ESC [ 3
4901 ~</tt> for kdch1, just like TERM=linux and
4902 TERM=vt220.</p></item>
4905 Emacs is programmed to map KB_Backspace or the `stty
4906 erase' character to delete-backward-char, and
4907 KB_Delete or kdch1 to delete-forward-char, and
4908 <tt>^H</tt> to help as always.</p></item>
4911 Other applications use the `stty erase' character and
4912 kdch1 for the two delete keys, with ASCII DEL being
4913 `delete previous character' and kdch1 being `delete
4914 character under cursor'.</p></item>
4918 This will solve the problem except for:</p>
4921 <list compact="compact">
4923 Some terminals have a <tt><--</tt> key that cannot
4924 be made to produce anything except <tt>^H</tt>. On
4925 these terminals Emacs help will be unavailable on
4926 <tt>^H</tt> (assuming that the `stty erase' character
4927 takes precedence in Emacs, and has been set
4928 correctly). M-x help or F1 (if available) can be used
4932 Some operating systems use <tt>^H</tt> for stty erase.
4933 However, modern telnet versions and all rlogin
4934 versions propagate stty settings, and almost all UNIX
4935 versions honour stty erase. Where the stty settings
4936 are not propagated correctly things can be made to
4937 work by using stty manually.</p></item>
4940 Some systems (including previous Debian versions) use
4941 xmodmap to arrange for both <tt><--</tt> and Delete
4942 to generate KB_Delete. We can change the behavior
4943 of their X clients via the same X resources that we
4944 use to do it for our own, or have our clients be
4945 configured via their resources when things are the
4946 other way around. On displays configured like this
4947 Delete will not work, but <tt><--</tt>
4951 Some operating systems have different kdch1 settings
4952 in their terminfo for xterm and others. On these
4953 systems the Delete key will not work correctly when
4954 you log in from a system conforming to our policy, but
4955 <tt><--</tt> will.</p></item>
4962 <heading>Environment variables</heading>
4965 A program must not depend on environment variables to get
4966 reasonable defaults. (That's because these environment
4967 variables would have to be set in a system-wide
4968 configuration file like /etc/profile, which is not supported
4972 If a program usually depends on environment variables for its
4973 configuration, the program should be changed to fall back to
4974 a reasonable default configuration if these environment
4975 variables are not present. If this cannot be done easily
4976 (e.g., if the source code of a non-free program is not
4977 available), the program must be replaced by a small
4978 `wrapper' shell script which sets the environment variables
4979 if they are not already defined, and calls the original program.</p>
4982 Here is an example of a wrapper script for this purpose:
4986 BAR=${BAR:-/var/lib/fubar}
4988 exec /usr/lib/foo/foo "$@"
4992 Furthermore, as <tt>/etc/profile</tt> is a configuration
4993 file of the <prgn>base-files</prgn> package, other packages must not
4994 put any environment variables or other commands into that
4999 <heading>Files</heading>
5003 <heading>Binaries</heading>
5006 Two different packages must not install programs with
5007 different functionality but with the same filenames. (The
5008 case of two programs having the same functionality but
5009 different implementations is handled via `alternatives.')
5010 If this case happens, one of the programs must be
5011 renamed. The maintainers should report this to the
5012 developers' mailing and try to find a consensus about
5013 which package will have to be renamed. If a consensus can
5014 not be reached, <em>both</em> programs must be
5018 Generally the following compilation parameters should be used:
5021 CFLAGS = -O2 -Wall # sane warning options vary between programs
5023 install -s # (or use strip on the files in debian/tmp)
5027 Note that by default all installed binaries should be stripped,
5028 either by using the <tt>-s</tt> flag to
5029 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5030 the binaries after they have been copied into
5031 <tt>debian/tmp</tt> but before the tree is made into a
5035 The <tt>-N</tt> flag should not be used. On a.out systems
5036 it may have been useful for some very small binaries, but
5037 for ELF it has no good effect.</p>
5040 Debugging symbols are useful for error diagnosis,
5041 investigation of core dumps (which may be submitted by users
5042 in bug reports), or testing and developing the
5043 software. Therefore it is recommended to support building
5044 the package with debugging information through the following
5045 interface: If the environment variable
5046 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5047 <tt>debug</tt>, compile the software with debugging
5048 information (usually this involves adding the <tt>-g</tt>
5049 flag to <tt>CFLAGS</tt>). This allows the generation of a
5050 build tree with debugging information. If the environment
5051 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5052 <tt>nostrip</tt>, do not strip the files at installation
5053 time. This allows one to generate a package with debugging
5054 information included. The following makefile snippet is only
5055 an example of how one may test for either condition:
5058 Rationale: Building by default with -g causes more
5059 wasted CPU cycles since the information is stripped away
5060 anyway. The package can by default build without -g if
5061 it also provides a mechanism to easily be rebuilt with
5062 debugging information. This can be done by providing a
5063 "build-debug" make target, or allowing the user to
5064 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5065 compiling that package.
5067 <p>Now this has several added benefits:
5071 It is actually easier to build debugging bins and
5072 libraries this way (no more editing debian/rules
5073 or similar) since it provides a documented way of
5074 getting this type of build.</p>
5078 There will be much less wasted CPU time for the
5079 autobuilders since not having debugging
5080 information (and hence also not having to strip
5081 it) will increase the speed of compiles. This
5082 skips an entire pass of the compiler.
5093 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5094 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5095 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5096 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5098 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5101 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5102 INSTALL_PROGRAM += -s
5106 Please note that the above example is merely informative,
5107 and is not a policy mandate. You may have to massage this
5108 example in order to make it work for your package.
5113 It is up to the package maintainer to decide what
5114 compilation options are best for the package. Certain
5115 binaries (such as computationally-intensive programs) will
5116 function better with certain flags (<tt>-O3</tt>, for
5117 example); feel free to use them. Please use good judgment
5118 here. Don't use flags for the sake of it; only use them
5119 if there is good reason to do so. Feel free to override
5120 the upstream author's ideas about which compilation
5121 options are best--they are often inappropriate for our
5122 environment.</p></sect>
5126 <heading>Libraries</heading>
5129 All libraries must have a shared version in the lib
5130 package and a static version in the lib-dev package. The
5131 shared version must be compiled with <tt>-fPIC</tt>, and
5132 the static version must not be. In other words, each
5133 <tt>*.c</tt> file will need to be compiled twice.</p>
5136 You must specify the gcc option <tt>-D_REENTRANT</tt>
5137 when building a library (either static or shared) to make
5138 the library compatible with LinuxThreads.</p>
5141 Note that all installed shared libraries should be
5144 strip --strip-unneeded <your-lib>
5146 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5147 only the symbols which aren't needed for relocation
5148 processing.) Shared libraries can function perfectly well
5149 when stripped, since the symbols for dynamic linking are
5150 in a separate part of the ELF object file.</p>
5153 Note that under some circumstances it may be useful to
5154 install a shared library unstripped, for example when
5155 building a separate package to support debugging.
5159 An ever increasing number of packages are using libtool to
5160 do their linking. The latest GNU libtools (>= 1.3a) can take
5161 advantage of the metadata in the installed libtool archive
5162 files (`*.la'). The main advantage of libtool's .la files is
5163 that it allows libtool to store and subsequently access
5164 metadata with respect to the libraries it builds. libtool
5165 will search for those files, which contain a lot of useful
5166 information about a library (e.g. dependency libraries for
5167 static linking). Also, they're <em>essential</em> for
5168 programs using libltdl.
5172 Certainly libtool is fully capable of linking against shared
5173 libraries which don't have .la files, but being a mere shell
5174 script it can add considerably to the build time of a
5175 libtool using package if that shell-script has to derive all
5176 this information from first principles for each library every
5177 time it is linked. With the advent of libtool-1.4 (and to a
5178 lesser extent libtool-1.3), the .la files will also store
5179 information about inter-library dependencies which cannot
5180 necessarily be derived after the .la file is deleted.
5184 Packages that use libtool to create shared libraries should
5185 include the <em>.la</em> files in the <em>-dev</em>
5186 packages, with the exception that if the package relies on
5187 libtool's <em>libltdl</em> library, in which case the .la
5188 files must go in the run-time library package. This is a
5189 good idea in general, and especially for static linking
5194 You must make sure that you use only released versions of
5195 shared libraries to build your packages; otherwise other
5196 users will not be able to run your binaries
5197 properly. Producing source packages that depend on
5198 unreleased compilers is also usually a bad
5205 <heading>Shared libraries</heading>
5208 Packages involving shared libraries should be split up
5209 into several binary packages.</p>
5212 For a straightforward library which has a development
5213 environment and a runtime kit including just shared
5214 libraries you need to create two packages:
5215 <tt><var>libraryname</var><var>soname</var></tt>
5216 (<var>soname</var> is the shared object name of the shared
5217 library--it's the thing that has to match exactly between
5218 building an executable and running it for the dynamic
5219 linker to be able run the program; usually the
5220 <var>soname</var> is the major number of the library) and
5221 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5224 If you prefer only to support one development version at a
5225 time you may name the development package
5226 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5227 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5228 ensure that the user only installs one development version
5229 at a time (after all, different development versions are
5230 likely to have the same header files in them, causing a
5231 filename clash if both are installed). Typically the
5232 development version should also have an exact version
5233 dependency on the runtime library, to make sure that
5234 compilation and linking happens correctly.</p>
5237 Packages which use the shared library should have a
5238 dependency on the name of the shared library package,
5239 <tt><var>libraryname</var><var>soname</var></tt>. When
5240 the <var>soname</var> changes you can have both versions
5241 of the library installed while moving from the old library
5245 If your package has some run-time support programs which
5246 use the shared library you must not put them in
5247 the shared library package. If you do that then you won't
5248 be able to install several versions of the shared library
5249 without getting filename clashes. Instead, either create
5250 a third package for the runtime binaries (this package
5251 might typically be named
5252 <tt><var>libraryname</var>-runtime</tt>--note the absence
5253 of the <var>soname</var> in the package name) or if the
5254 development package is small include them in there.</p>
5257 If you have several shared libraries built from the same
5258 source tree you may lump them all together into a single
5259 shared library package, provided that you change all their
5260 <var>soname</var>s at once (so that you don't get filename
5261 clashes if you try to install different versions of the
5262 combined shared libraries package).</p>
5265 You should follow the directions in the <em>Debian Packaging
5266 Manual</em> for putting the shared library in its package,
5267 and you must include a <tt>shlibs</tt> control area
5268 file with details of the dependencies for packages which
5269 use the library.</p>
5272 Shared libraries should not be installed
5273 executable, since <prgn>ld.so</prgn> does not require this
5274 and trying to execute a shared library results in a core
5279 <heading>Scripts</heading>
5282 All command scripts, including the package maintainer
5283 scripts inside the package and used by <prgn>dpkg</prgn>,
5284 should have a <tt>#!</tt> line naming the shell to be used
5285 to interpret them.</p>
5288 In the case of Perl scripts this should be
5289 <tt>#!/usr/bin/perl</tt>.</p>
5292 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5293 should almost certainly start with <tt>set -e</tt> so that
5294 errors are detected. Every script should use
5295 <tt>set -e</tt> or check the exit status of <em>every</em>
5299 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5300 symbolic link to any POSIX compatible shell, if <tt>echo
5301 -n</tt> does not generate a newline.
5304 Debian policy specifies POSIX behavior for /bin/sh, but
5305 echo -n has widespread use in the Linux community
5306 (including especially debian policy, the linux kernel
5307 source, many debian scripts, etc.). This echo -n
5308 mechanism is valid but not required under POSIX, hence
5309 this explicit addition. Also, rumour has it that this
5310 shall be mandated under the LSB anyway.
5314 specifying `<tt>/bin/sh</tt>' as interpreter should only
5315 use POSIX features. If a script requires non-POSIX
5316 features from the shell interpreter, the appropriate shell
5317 must be specified in the first line of the script (e.g.,
5318 `<tt>#!/bin/bash</tt>') and the package must depend on the
5319 package providing the shell (unless the shell package is
5320 marked `Essential', e.g., in the case of
5325 You may wish to restrict your script to POSIX features when possible so
5326 that it may use <tt>/bin/sh</tt> as its interpreter. If
5327 your script works with <prgn>ash</prgn>, it's probably
5328 POSIX compliant, but if you are in doubt, use
5329 <tt>/bin/bash</tt>.</p>
5332 Perl scripts should check for errors when making any
5333 system calls, including <tt>open</tt>, <tt>print</tt>,
5334 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5337 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5338 as scripting languages. See <em>Csh Programming
5339 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5340 FAQs. It can be found on
5341 <url id="http://language.perl.com/versus/csh.whynot">, or
5342 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5343 or even on <ftpsite>ftp.cpan.org</ftpsite>
5344 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5345 If an upstream package comes with <prgn>csh</prgn> scripts
5346 then you must make sure that they start with
5347 <tt>#!/bin/csh</tt> and make your package depend on the
5348 <prgn>c-shell</prgn> virtual package.</p>
5351 Any scripts which create files in world-writeable
5352 directories (e.g., in <tt>/tmp</tt>) must use a
5353 mechanism which will fail if a file with the same name
5357 The Debian base distribution provides the
5358 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5359 for use by scripts for this purpose.</p></sect>
5363 <heading>Symbolic links</heading>
5366 In general, symbolic links within a top-level directory
5367 should be relative, and symbolic links pointing from one
5368 top-level directory into another should be absolute. (A
5369 top-level directory is a sub-directory of the root
5373 In addition, symbolic links should be specified as short
5374 as possible, i.e., link targets like `foo/../bar' are
5378 Note that when creating a relative link using
5379 <prgn>ln</prgn> it is not necessary for the target of the
5380 link to exist relative to the working directory you're
5381 running <prgn>ln</prgn> from; nor is it necessary to
5382 change directory to the directory where the link is to be
5383 made. Simply include the string that should appear as the
5384 target of the link (this will be a pathname relative to
5385 the directory in which the link resides) as the first
5386 argument to <prgn>ln</prgn>.</p>
5389 For example, in your <prgn>Makefile</prgn> or
5390 <tt>debian/rules</tt>, do things like:
5392 ln -fs gcc $(prefix)/bin/cc
5393 ln -fs gcc debian/tmp/usr/bin/cc
5394 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5395 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5399 A symbolic link pointing to a compressed file should
5400 always have the same file extension as the referenced
5401 file. (For example, if a file `<tt>foo.gz</tt>' is
5402 referenced by a symbolic link, the filename of the link
5403 has to end with `<tt>.gz</tt>' too, as in
5404 `bar.gz.')</p></sect>
5408 <heading>Device files</heading>
5411 Packages must not include device files in the package file
5415 If a package needs any special device files that are not
5416 included in the base system, it must call
5417 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5418 after asking the user for permission to do so.</p>
5421 Packages must not remove any device files in the
5422 <tt>postrm</tt> or any other script. This is left to the
5423 system administrator.</p>
5426 Debian uses the serial devices
5427 <tt>/dev/ttyS*</tt>. Programs using the old
5428 <tt>/dev/cu*</tt> devices should be changed to use
5429 <tt>/dev/ttyS*</tt>.</p>
5432 <sect id="config files">
5433 <heading>Configuration files</heading>
5435 <heading>Definitions</heading>
5438 <tag>configuration file</tag>
5440 A file that affects the operation of program, or
5441 provides site- or host-specific information, or
5442 otherwise customizes the behavior of program.
5443 Typically, configuration files are intended to be
5444 modified by the system administrator (if needed or
5445 desired) to conform to local policy or provide more
5446 useful site-specific behavior.</p>
5449 <tag><tt>conffile</tt></tag>
5451 A file listed in a package's <tt>conffiles</tt>
5452 file, and is treated specially by <prgn>dpkg</prgn>
5453 (see the <em>Debian Packaging Manual</em>).</p>
5459 The distinction between these two is important; they are
5460 not interchangeable concepts. Almost all
5461 <tt>conffiles</tt> are configuration files, but many
5462 configuration files are not <tt>conffiles</tt>.</p>
5465 Note that a script that embeds configuration information
5466 (such as most of the files in <tt>/etc/init.d</tt> and
5467 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5468 configuration file and should be treated as such.</p>
5472 <heading>Location</heading>
5474 Any configuration files created or used by your package
5475 must reside in <tt>/etc</tt>. If there are several you
5476 should consider creating a subdirectory of <tt>/etc</tt>
5477 named after your package.</p>
5480 If your package creates or uses configuration files
5481 outside of <tt>/etc</tt>, and it is not feasible to modify
5482 the package to use the <tt>/etc</tt>, you should still put
5483 the files in <tt>/etc</tt> and create symbolic links to
5484 those files from the location that the package
5489 <heading>Behavior</heading>
5491 Configuration file handling must conform to the following
5495 <p>local changes must be preserved during a package
5499 <p>configuration files must be preserved when the
5500 package is removed, and only deleted when the
5501 package is purged.</p>
5506 The easy way to achieve this behavior is to make the
5507 configuration file a <tt>conffile</tt>. This is
5508 appropriate only if it is possible to distribute a default
5509 version that will work for most installations, although
5510 some system administrators may choose to modify it. This
5511 implies that the default version will be part of the
5512 package distribution, and must not be modified by the
5513 maintainer scripts during installation (or at any other
5518 In order to ensure that local changes are preserved
5519 correctly, no package may contain or make hard links to
5523 Rationale: There are two problems with hard links.
5524 The first is that some editors break the link while
5525 editing one of the files, so that the two files may
5526 unwittingly become different. The second is that
5527 <prgn>dpkg</prgn> might break the hard link while
5528 upgrading <tt>conffile</tt>s.
5534 The other way to do it is via the maintainer scripts.
5535 In this case, the configuration file must not be listed as
5536 a <tt>conffile</tt> and must not be part of the package
5537 distribution. If the existence of a file is required for
5538 the package to be sensibly configured it is the
5539 responsibility of the package maintainer to write scripts
5540 which correctly create, update, maintain and
5541 remove-on-purge the file. These scripts must be idempotent
5542 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5543 re-run them due to errors during installation or removal),
5544 must cope with all the variety of ways <prgn>dpkg</prgn>
5545 can call maintainer scripts, must not overwrite or
5546 otherwise mangle the user's configuration without asking,
5547 must not ask unnecessary questions (particularly during
5548 upgrades), and otherwise be good citizens.</p>
5551 The scripts are not required to configure every possible option for
5552 the package, but only those necessary to get the package
5553 running on a given system. Ideally the sysadmin should not
5554 have to do any configuration other than that done
5555 (semi-)automatically by the <tt>postinst</tt> script.</p>
5558 A common practice is to create a script called
5559 <tt><var>package</var>-configure</tt> and have the
5560 package's <tt>postinst</tt> call it if and only if the
5561 configuration file does not already exist. In certain
5562 cases it is useful for there to be an example or template
5563 file which the maintainer scripts use. Such files should
5564 be in <tt>/usr/share/<package></tt> or
5565 <tt>/usr/lib/<package></tt> with a symbolic link
5566 from <tt>/usr/share/doc/<package>/examples</tt>
5567 if they are examples, and should be
5568 perfectly ordinary <prgn>dpkg</prgn>-handled files
5569 (<em>not</em> <tt>conffiles</tt>).
5573 These two styles of configuration file handling must
5574 not be mixed, for that way lies madness:
5575 <prgn>dpkg</prgn> will ask about overwriting the file
5576 every time the package is upgraded.</p>
5581 <heading>Sharing configuration files</heading>
5583 Packages which specify the same file as
5584 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5589 The maintainer scripts must not alter the conffile of
5590 <em>any</em> package, including the one the scripts belong
5594 If two or more packages use the same configuration file
5595 and it is reasonable for both to be installed at the same
5596 time, one of these packages must be defined as
5597 <em>owner</em> of the configuration file, i.e., it will be
5598 the package to list that distributes the file and lists it
5599 as a <tt>conffile</tt>. Other packages that use the
5600 configuration file must depend on the owning package if
5601 they require the configuration file to operate. If the
5602 other package will use the configuration file if present,
5603 but is capable of operating without it, no dependency need
5607 If it is desirable for two or more related packages to
5608 share a configuration file <em>and</em> for all of the
5609 related packages to be able to modify that configuration
5610 file, then the following should be done:
5614 have one of the related packages (the "core"
5615 package) manage the configuration file with
5616 maintainer scripts as described in the previous
5620 the core package should also provide a program that
5621 the other packages may use to modify the
5622 configuration file.</p>
5626 the related packages must use the provided program
5627 to make any modifications to the configuration file.
5628 They should either depend on the core package to
5629 guarantee that the configuration modifier program is
5630 available or accept gracefully that they cannot
5631 modify the configuration file if it is not.</p>
5636 Sometimes it's appropriate to create a new package which
5637 provides the basic infrastructure for the other packages
5638 and which manages the shared configuration files. (Check
5639 out the <tt>sgml-base</tt> package as an example.)</p>
5643 <heading>User configuration files ("dotfiles")</heading>
5646 Files in <tt>/etc/skel</tt> will automatically be copied
5647 into new user accounts by <prgn>adduser</prgn>. They
5648 should not be referenced there by any program.</p>
5651 Therefore, if a program needs a dotfile to exist in
5652 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5653 should be installed in <tt>/etc/skel</tt> (and listed in
5654 conffiles, if it is not generated and modified dynamically
5655 by the package's installation scripts).</p>
5658 However, programs that require dotfiles in order to
5659 operate sensibly (dotfiles that they do not create
5660 themselves automatically, that is) are a bad thing, and
5661 programs should be configured by the Debian default
5662 installation as close to normal as possible.</p>
5665 Therefore, if a program in a Debian package needs to be
5666 configured in some way in order to operate sensibly that
5667 configuration should be done in a site-wide global
5668 configuration file elsewhere in <tt>/etc</tt>. Only if the
5669 program doesn't support a site-wide default configuration
5670 and the package maintainer doesn't have time to add it
5671 may a default per-user file be placed in
5672 <tt>/etc/skel</tt>.</p>
5675 <tt>/etc/skel</tt> should be as empty as we can make it.
5676 This is particularly true because there is no easy
5677 mechanism for ensuring that the appropriate dotfiles are
5678 copied into the accounts of existing users when a package
5684 <heading>Log files</heading>
5686 The traditional approach to log files has been to set up ad
5687 hoc log rotation schemes using simple shell scripts and
5688 cron. While this approach is highly customizable, it
5689 requires quite a lot of sysadmin work. Even though the
5690 original Debian system helped a little by automatically
5691 installing a system which can be used as a template, this
5692 was deemed not enough.
5696 A better scheme is to use logrotate, a GPL'd program
5697 developed by Red Hat, which centralizes log management. It
5698 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5699 and a directory where packages can drop logrotation info
5700 (<tt>/etc/logrotate.d</tt>).
5704 Log files should usually be named
5705 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5706 log files, or need a separate directory for permissions
5707 reasons (<tt>/var/log</tt> is writable only by
5708 <tt>root</tt>), you should usually create a directory named
5709 <tt>/var/log/<var>package</var></tt>.</p>
5712 Log files must be rotated occasionally so
5713 that they don't grow indefinitely; the best way to do this
5714 is to drop a script into the directory
5715 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5716 logrotate. Here is a good example for a logrotate config
5717 file (for more information see <manref name="logrotate"
5725 /etc/init.d/foo force-reload
5729 Which rotates all files under `/var/log/foo', saves 12
5730 compressed generations, and sends a HUP signal at the end of
5736 Log files should be removed when the package is
5737 purged (but not when it is only removed), by checking the
5738 argument to the <tt>postrm</tt> script (see the <em>Debian
5739 Packaging Manual</em> for details).</p>
5744 <heading>Permissions and owners</heading>
5747 The rules in this section are guidelines for general use.
5748 If necessary you may deviate from the details below.
5749 However, if you do so you must make sure that what is done
5750 is secure and you should try to be as consistent as possible
5751 with the rest of the system. You should probably also
5752 discuss it on <prgn>debian-devel</prgn> first.</p>
5755 Files should be owned by <tt>root.root</tt>, and made
5756 writable only by the owner and universally readable (and
5757 executable, if appropriate).</p>
5760 Directories should be mode 755 or (for group-writability)
5761 mode 2775. The ownership of the directory should be
5762 consistent with its mode--if a directory is mode 2775, it
5763 should be owned by the group that needs write access to
5767 Setuid and setgid executables should be mode 4755 or 2755
5768 respectively, and owned by the appropriate user or group.
5769 They should not be made unreadable (modes like 4711 or
5770 2711 or even 4111); doing so achieves no extra security,
5771 because anyone can find the binary in the freely available
5772 Debian package--it is merely inconvenient. For the same
5773 reason you should not restrict read or execute permissions
5774 on non-set-id executables.</p>
5777 Some setuid programs need to be restricted to particular
5778 sets of users, using file permissions. In this case they
5779 should be owned by the uid to which they are set-id, and
5780 by the group which should be allowed to execute them.
5781 They should have mode 4754; there is no point in making
5782 them unreadable to those users who must not be allowed to
5786 You must not arrange that the system administrator can only
5787 reconfigure the package to correspond to their local
5788 security policy by changing the permissions on a binary.
5789 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5790 to conffiles and other similar objects) have their
5791 permissions reset to the distributed permissions when the
5792 package is reinstalled. Instead you should consider (for
5793 example) creating a group for people allowed to use the
5794 program(s) and making any setuid executables executable
5795 only by that group.</p>
5798 If you need to create a new user or group for your package
5799 there are two possibilities. Firstly, you may need to
5800 make some files in the binary package be owned by this
5801 user or group, or you may need to compile the user or
5802 group id (rather than just the name) into the binary
5803 (though this latter should be avoided if possible, as in
5804 this case you need a statically allocated id).</p>
5807 If you need a statically allocated id, you must ask for a
5808 user or group id from the base system
5809 maintainer, and must not release the package until you
5810 have been allocated one. Once you have been allocated one
5811 you must make the package depend on a version of the base
5812 system with the id present in <tt>/etc/passwd</tt> or
5813 <tt>/etc/group</tt>, or alternatively arrange for your
5814 package to create the user or group itself with the
5815 correct id (using <tt>adduser</tt>) in its pre- or
5816 post-installation script (the latter is to be preferred if
5817 it is possible).</p>
5820 On the other hand, the program might be able to determine the
5821 uid or gid from the group name at runtime, so that a
5822 dynamic id can be used. In this case you should choose an
5823 appropriate user or group name, discussing this on
5824 <prgn>debian-devel</prgn> and checking with the base
5825 system maintainer that it is unique and that they do not
5826 wish you to use a statically allocated id instead. When
5827 this has been checked you must arrange for your package to
5828 create the user or group if necessary using
5829 <prgn>adduser</prgn> in the pre- or post-installation
5830 script (again, the latter is to be preferred if it is
5834 Note that changing the numeric value of an id associated with a name
5835 is very difficult, and involves searching the file system for all
5836 appropriate files. You need to think carefully whether a static or
5837 dynamic id is required, since changing your mind later will cause
5843 <heading>Customized programs</heading>
5845 <sect id="arch-spec">
5846 <heading>Architecture specification strings</heading>
5849 If a program needs to specify an <em>architecture specification
5850 string</em> in some place, the following format should be used:
5852 <arch>-<os>
5854 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5855 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5856 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5857 operating system.</p>
5859 Note, that we don't want to use `<arch>-debian-linux'
5860 to apply to the rule `architecture-vendor-os' since this
5861 would make our programs incompatible to other Linux
5862 distributions. Also note, that we don't use
5863 `<arch>-unknown-linux', since the `unknown' does not
5864 look very good.</p></sect>
5868 <heading>Daemons</heading>
5871 The configuration files <tt>/etc/services</tt>,
5872 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5873 by the <prgn>netbase</prgn> package and may not be modified
5874 by other packages.</p>
5877 If a package requires a new entry in one of these files, the
5878 maintainer should get in contact with the
5879 <prgn>netbase</prgn> maintainer, who will add the entries
5880 and release a new version of the <prgn>netbase</prgn>
5884 The configuration file <tt>/etc/inetd.conf</tt> must not be
5885 modified by the package's scripts except via the
5886 <prgn>update-inetd</prgn> script or the
5887 <prgn>DebianNet.pm</prgn> Perl module.</p>
5890 If a package wants to install an example entry into
5891 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5892 exactly one hash character (<tt>#</tt>). Such lines are
5893 treated as `commented out by user' by the
5894 <prgn>update-inetd</prgn> script and are not changed or
5895 activated during a package updates.</p></sect>
5899 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5902 Some programs need to create pseudo-ttys. This should be done
5903 using Unix98 ptys if the C library supports it. The resulting
5904 program must not be installed setuid root, unless that
5905 is required for other functionality.
5909 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5910 <tt>/var/log/lastlog</tt> must be installed writeable by
5911 group utmp. Programs who need to modify those files must
5912 be installed setgid utmp.
5917 <heading>Editors and pagers</heading>
5920 Some programs have the ability to launch an editor or pager
5921 program to edit or display a text document. Since there are
5922 lots of different editors and pagers available in the Debian
5923 distribution, the system administrator and each user should
5924 have the possibility to choose his/her preferred editor and
5928 In addition, every program should choose a good default
5929 editor/pager if none is selected by the user or system
5933 Thus, every program that launches an editor or pager must
5934 use the EDITOR or PAGER environment variables to determine
5935 the editor/pager the user wants to get started. If these
5936 variables are not set, the programs <tt>/usr/bin/editor</tt>
5937 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5940 These two files are managed through `alternatives.' That is,
5941 every package providing an editor or pager must call the
5942 <prgn>update-alternatives</prgn> script to register these
5946 If it is very hard to adapt a program to make us of the
5947 EDITOR and PAGER variables, that program may be configured
5948 to use <tt>/usr/bin/sensible-editor</tt> and
5949 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5950 respectively. These are two scripts provided in the Debian
5951 base system that check the EDITOR and PAGER variables and
5952 launch the appropriate program or fall back to
5953 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5957 A program may also use the VISUAL environment variable to
5958 determine the user's choice of editor. If it exists, it
5959 should take precedence over EDITOR. This is in fact what
5960 <tt>/usr/bin/sensible-editor</tt> does.</p>
5963 It is not required for a package to depend on
5964 `editor' and `pager', nor is it required for a package to
5965 provide such virtual packages.
5968 The Debian base system already provides an editor and
5977 <sect id="web-appl">
5978 <heading>Web servers and applications</heading>
5981 This section describes the locations and URLs that should
5982 be used by all web servers and web application in the Debian
5988 <p>Cgi-bin executable files are installed in the
5991 /usr/lib/cgi-bin/<cgi-bin-name>
5993 and should be referred to as
5995 http://localhost/cgi-bin/<cgi-bin-name>
5996 </example></p></item>
5999 <item><p>Access to html documents</p>
6002 Html documents for a package are stored in
6003 <tt>/usr/share/doc/<var>package</var></tt> but should
6004 be accessed via symlinks as
6005 <tt>/usr/doc/<var>package</var></tt><footnote> for
6006 backward compatibility, see <ref id="usrdoc"></footnote>
6007 and can be referred to as
6009 http://localhost/doc/<package>/<filename>
6010 </example></p></item>
6013 <item><p>Web Document Root</p>
6016 Web Applications should try to avoid storing files in
6017 the Web Document Root. Instead they should use the
6018 /usr/share/doc/<package> directory for documents and
6019 register the Web Application via the menu package. If
6020 access to the web-root is unavoidable then use
6024 as the Document Root. This might be just a
6025 symbolic link to the location where the sysadmin has
6026 put the real document root.</p>
6029 </enumlist></p></sect>
6033 <heading>Mail transport, delivery and user agents</heading>
6036 Debian packages which process electronic mail, whether
6037 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6038 must make sure that they are compatible with the
6039 configuration decisions below. Failure to do this may
6040 result in lost mail, broken <tt>From:</tt> lines, and other
6041 serious brain damage!</p>
6044 The mail spool is <tt>/var/spool/mail</tt> and the interface
6045 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6046 per the FHS). The mail spool is part of the base system
6047 and not part of the MTA package.</p>
6050 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6051 programs (like IMAP daemons) must lock the mailbox in an
6052 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6053 be combined with dot locking. To avoid deadlocks, a
6054 program should use <tt>fcntl()</tt> first and dot locking
6055 after this or alternatively implement the two locking
6056 methods in a non blocking way<footnote>
6058 If it is not possible to establish both locks, the
6059 system shouldn't wait for the second lock to be
6060 established, but remove the first lock, wait a (random)
6061 time, and start over locking again.</p>
6062 </footnote>. Using the functions <tt>maillock</tt> and
6063 <tt>mailunlock</tt> provided by the
6064 <tt>liblockfile*</tt><footnote>
6066 <tt>liblockfile</tt> version >>1.01</p>
6067 </footnote> packages is the recommended way to realize this.
6071 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6072 unless the user has chosen otherwise. A MUA may remove a
6073 mailbox (unless it has nonstandard permissions) in which
6074 case the MTA or another MUA must recreate it if needed.
6075 Mailboxes must be writable by group mail.</p>
6078 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6079 be setgid mail to do the locking mentioned above (and
6080 must obviously avoid accessing other users' mailboxes
6081 using this privilege).</p>
6084 <tt>/etc/aliases</tt> is the source file for the system mail
6085 aliases (e.g., postmaster, usenet, etc.)--it is the one
6086 which the sysadmin and <tt>postinst</tt> scripts may edit.
6087 After <tt>/etc/aliases</tt> is edited the program or human
6088 editing it must call <prgn>newaliases</prgn>. All MTA
6089 packages must come with a <prgn>newaliases</prgn> program,
6090 even if it does nothing, but older MTA packages do not do
6091 this so programs should not fail if <prgn>newaliases</prgn>
6092 cannot be found.</p>
6095 The convention of writing <tt>forward to
6096 <var>address</var></tt> in the mailbox itself is not
6097 supported. Use a <tt>.forward</tt> file instead.</p>
6100 The <prgn>rmail</prgn> program used by UUCP
6101 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6102 Likewise, <prgn>rsmtp</prgn>, for receiving
6103 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6107 If you need to know what name to use (for example) on
6108 outgoing news and mail messages which are generated locally,
6109 you should use the file <tt>/etc/mailname</tt>. It will
6110 contain the portion after the username and <tt>@</tt> (at)
6111 sign for email addresses of users on the machine (followed
6115 A package should check for the existence of this file. If
6116 it exists it should use it without comment. (An MTA's
6117 prompting configuration script may wish to prompt the user
6118 even if it finds this file exists.) If it does not exist it
6119 should prompt the user for the value and store it in
6120 <tt>/etc/mailname</tt> as well as using it in the package's
6121 configuration. The prompt should make it clear that the
6122 name will not just be used by that package. For example, in
6123 this situation the INN package says:
6125 Please enter the `mail name' of your system. This is the
6126 hostname portion of the address to be shown on outgoing
6127 news and mail messages. The default is
6128 <var>syshostname</var>, your system's host name. Mail
6129 name [`<var>syshostname</var>']:
6131 where <var>syshostname</var> is the output of <tt>hostname
6132 --fqdn</tt>.</p></sect>
6136 <heading>News system configuration</heading>
6139 All the configuration files related to the NNTP (news)
6140 servers and clients should be located under
6141 <tt>/etc/news</tt>.</p>
6144 There are some configuration issues that apply to a number
6145 of news clients and server packages on the machine. These
6149 <tag>/etc/news/organization</tag>
6150 <item><p>A string which should appear as the
6151 organization header for all messages posted
6152 by NNTP clients on the machine</p></item>
6154 <tag>/etc/news/server</tag>
6155 <item><p>Contains the FQDN of the upstream NNTP
6156 server, or localhost if the local machine is
6157 an NNTP server.</p></item>
6160 Other global files may be added as required for cross-package news
6161 configuration.</p></sect>
6165 <heading>Programs for the X Window System</heading>
6168 <em>Programs that may be configured with support for the X Window
6169 System</em> must be configured to do so and must declare any
6170 package dependencies necessary to satisfy their runtime
6171 requirements when using the X Window System, unless the package
6172 in question is of standard or higher priority, in which case
6173 X-specific binaries may be split into a separate package, or
6174 alternative versions of the package with X support may be
6180 <em>Packages which provide an X server</em> that, directly or
6181 indirectly, communicates with real input and display hardware
6182 should declare in their control data that they provide the
6183 virtual package <tt>xserver</tt>.
6186 This implements current practice, and provides an actual
6187 policy for usage of the "xserver" virtual package which
6188 appears in the virtual packages list. In a nutshell, X
6189 servers that interface directly with the display and input
6190 hardware or via another subsystem (e.g., GGI) should provide
6191 xserver. Things like Xvfb, Xnest, and Xprt should not.
6197 <em>Packages that provide a terminal emulator</em> for the X
6198 Window System which support a terminal type with a terminfo
6199 description provided in the <tt>ncurses-base</tt> package
6200 should declare in their control data that they provide the
6201 virtual package <tt>x-terminal-emulator</tt>. They should
6202 also register themselves as an alternative for
6203 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6208 <em>Packages that provide window managers</em> should declare in
6209 their control data that they provide the virtual package
6210 <tt>x-window-manager</tt>. They should also register themselves as an
6211 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6212 calculated as follows:
6214 <item>Start with a priority of 20.</item>
6215 <item>If the window manager supports the Debian menu system,
6216 add 20 points if this support is available in the
6217 package's default configuration (i.e., no
6218 configuration files belonging to the system or user
6219 have to be edited to activate the feature); if
6220 configuration files must be modified, add only 10
6222 <item>If the window manager permits the X session to be
6223 restarted using a <em>different</em> window manager
6224 (without killing the X server) in its default
6225 configuration, add 10 points; otherwise add
6231 <em>Packages that provide fonts for the X Window System</em>
6232 must do a number of things to ensure that they are both
6233 available without modification of the X or font server
6234 configuration, and that they do not corrupt files used by
6235 other font packages to register information about themselves.
6238 Fonts of any type supported by the X Window System
6239 should be be in a separate binary package from any
6240 executables, libraries, or documentation (except that
6241 specific to the fonts shipped); if a program or
6242 library is <em>unusable</em> without one or more
6243 specific fonts, the package containing the program or
6244 library should declare a dependency on the package(s)
6245 containing the font(s) it requires.
6248 BDF fonts should be converted to PCF fonts with the
6249 <tt>bdftopcf</tt> utility (available in the
6250 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6251 placed in a directory that corresponds to their
6255 100 dpi fonts should be placed in
6256 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6259 75 dpi fonts should be placed in
6260 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6263 Character-cell fonts, cursor fonts, and other
6264 low-resolution fonts should be placed in
6265 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6270 Speedo fonts should be placed in
6271 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6274 Type 1 fonts should be placed in
6275 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6276 metric files are available, they may be placed here as
6280 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6281 other than those listed above should be neither created nor
6282 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6283 excepted for historical reasons, but installation of files into
6284 these directories remains discouraged.)
6287 Font packages may, instead of placing files directly in
6288 the X font directories listed above, provide symbolic links in
6289 the font directory which point to the files' actual location
6290 in the filesystem. Such a location should comply with the
6294 Font packages should not contain both 75dpi and 100dpi
6295 versions of a font. If both are available, they should be
6296 provided in separate binary packages with "-75dpi" or "-100dpi"
6297 appended to the names of the packages containing the
6298 corresponding fonts.
6301 Fonts destined for the <tt>misc</tt> subdirectory should
6302 not be included in the same package as 75dpi or 100dpi fonts;
6303 instead, they should be provided in a separate package with
6304 "-misc" appended to its name.
6307 Font packages <em>must not</em> provide the files
6308 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6309 <tt>fonts.scale</tt> in a font directory.
6312 <tt>fonts.dir</tt> files must not be provided at
6316 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6317 files, if needed, should be provided in the
6319 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6320 where <em>fontdir</em> is the name of the
6322 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6323 package's corresponding fonts are stored (e.g.,
6324 <tt>75dpi</tt> or <tt>misc</tt>),
6325 <em>package</em> is the name of the package that
6326 provides these fonts, and <em>extension</em> is
6327 either <tt>scale</tt> or <tt>alias</tt>,
6328 whichever corresponds to the file
6334 Font packages must declare a dependency on
6335 <tt>xutils</tt> and, in the package
6336 post-installation and post-removal scripts, invoke the
6337 <tt>mkfontdir</tt> command on each directory into
6338 which they installed fonts.
6341 Font packages that provide one or more
6342 <tt>fonts.scale</tt> files as described above must declare a
6343 versioned dependency on <tt>xutils (>=
6344 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6345 directory into which they installed fonts
6346 <em>before</em> invoking <tt>mkfontdir</tt> on that
6347 directory. This invocation must occur in both the
6348 post-installation and post-removal scripts.
6351 Font packages that provide one or more
6352 <tt>fonts.alias</tt> files as described above must
6353 declare a versioned dependency on <tt>xutils
6354 (>= 4.0.2)</tt> and, in the package
6355 post-installation and post-removal scripts, invoke
6356 <tt>update-fonts-alias</tt> on each directory into
6357 which they installed fonts.
6360 Font packages must not provide alias names for the
6361 fonts they include which collide with alias names already in
6362 use by fonts already packaged.
6365 Font packages must not provide fonts with the same XLFD
6366 registry name as another font already packaged.
6372 <em>Application defaults</em> files must be installed in the
6373 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6374 localized subdirectory of <tt>/etc/X11/</tt> as described in
6375 the <em>X Toolkit Intrinsics - C Language Interface</em>
6376 manual is also permitted). They must be registered as
6377 <em>conffile</em>s or handled as configuration files. For
6378 programs that are not linked against the X Toolkit (Xt)
6379 library, customization of programs' X resources may also be
6380 supported with the provision of a file with the same name as
6381 that of the package placed in the
6382 <tt>/etc/X11/Xresources/</tt> directory, which must
6383 registered as a <em>conffile</em> or handled as a
6384 configuration file. <em>Important:</em> packages that
6385 install files into the <tt>/etc/X11/Xresources/</tt>
6386 directory <em>must</em> declare a conflict with <tt>xbase
6387 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6388 possible for the installing package to destroy a
6389 previously-existing <tt>/etc/X11/Xresources</tt> file which
6390 had been customized by the system administrator.
6394 <em>Packages using the X Window System should abide by the FHS
6395 standard whenever possible</em>; they should install binaries,
6396 libraries, manual pages, and other files in FHS-mandated
6397 locations wherever possible. This means that files must
6398 not be installed into <tt>/usr/X11R6/bin/</tt>,
6399 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6400 this is necessary for the package to operate properly.
6401 Configuration files for window managers and display managers
6402 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6403 corresponding to the package name due to these programs'
6404 tight integration with the mechanisms of the X Window
6405 System. Application-level programs should use the
6406 <tt>/etc/</tt> directory unless otherwise mandated by
6407 policy. The installation of files into subdirectories of
6408 <tt>/usr/X11R6/include/X11/</tt> and
6409 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6410 package maintainers should determine if subdirectories of
6411 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6412 instead (symlinks from the X11R6 directories to
6413 FHS-compliant locations is encouraged if the program is not
6414 easily configured to look elsewhere for its files).
6415 Packages must not provide -- or install files into -- the
6416 directories <tt>/usr/bin/X11/</tt>,
6417 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6418 Files within a package should, however, make reference to
6419 these directories, rather than their X11R6-named
6420 counterparts <tt>/usr/X11R6/bin/</tt>,
6421 <tt>/usr/X11R6/include/X11/</tt>, and
6422 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6423 referred to have not been moved to FHS-compliant locations.
6427 <em>Programs that require the non-DFSG-compliant OSF/Motif
6428 library</em> should be compiled against and tested with
6429 LessTif (a free re-implementation of Motif) instead. If the
6430 maintainer judges that the program or programs do not work
6431 sufficiently well with LessTif to be distributed and
6432 supported, but do so when compiled against Motif, then two
6433 versions of the package should be created; one linked
6434 statically against Motif and with <tt>-smotif</tt> appended
6435 to the package name, and one linked dynamically against
6436 Motif and with <tt>-dmotif</tt> appended to the package
6437 name. Both Motif-linked versions are dependent upon
6438 non-DFSG-compliant software and thus cannot be uploaded to
6439 the main distribution; if the software is itself
6440 DFSG-compliant it may be uploaded to the contrib
6441 distribution. While known existing versions of OSF/Motif
6442 permit unlimited redistribution of binaries linked against
6443 the library (whether statically or dynamically), it is the
6444 package maintainer's responsibility to determine whether
6445 this is permitted by the license of the copy of OSF/Motif in
6446 his or her possession.
6452 <heading>Emacs lisp programs</heading>
6455 Please refer to the `Debian Emacs Policy' (documented in
6456 <tt>debian-emacs-policy.gz</tt> of the
6457 <prgn>emacsen-common</prgn> package) for details of how to
6458 package emacs lisp programs.</p></sect>
6462 <heading>Games</heading>
6465 The permissions on /var/games are 755
6466 <tt>root.root</tt>.</p>
6469 Each game decides on its own security policy.</p>
6472 Games which require protected, privileged access to
6473 high-score files, savegames, etc., may be made
6474 set-<em>group</em>-id (mode 2755) and owned by
6475 <tt>root.games</tt>, and use files and directories with
6476 appropriate permissions (770 <tt>root.games</tt>, for
6477 example). They must not be made
6478 set-<em>user</em>-id, as this causes security problems. (If
6479 an attacker can subvert any set-user-id game they can
6480 overwrite the executable of any other, causing other players
6481 of these games to run a Trojan horse program. With a
6482 set-group-id game the attacker only gets access to less
6483 important game data, and if they can get at the other
6484 players' accounts at all it will take considerably more
6488 Some packages, for example some fortune cookie programs, are
6489 configured by the upstream authors to install with their
6490 data files or other static information made unreadable so
6491 that they can only be accessed through set-id programs
6492 provided. You should not do this in a Debian package: anyone can
6493 download the <tt>.deb</tt> file and read the data from it,
6494 so there is no point making the files unreadable. Not
6495 making the files unreadable also means that you don't have
6496 to make so many programs set-id, which reduces the risk of a
6500 As described in the FHS, binaries of games should be
6501 installed in the directory <tt>/usr/games</tt>. This also
6502 applies to games that use the X Window System. Manual pages
6503 for games (X and non-X games) should be installed in
6504 <tt>/usr/share/man/man6</tt>.</p>
6508 <chapt><heading>Documentation</heading>
6512 <heading>Manual pages</heading>
6515 You should install manual pages in <prgn>nroff</prgn> source
6516 form, in appropriate places under <tt>/usr/share/man</tt>. You
6517 should only use sections 1 to 9 (see the FHS for more
6518 details). You must not install a preformatted `cat
6522 Each program, utility, and function should have an
6523 associated manpage included in the same package. It is
6524 suggested that all configuration files also have a manual
6525 page included as well.
6529 If no manual page is available for a particular program,
6530 utility, function or configuration file and this is reported as a bug on
6531 debian-bugs, a symbolic link from the requested manual page
6532 to the <manref name="undocumented" section="7"> manual page
6533 may be provided. This symbolic link can be created from
6534 <tt>debian/rules</tt> like this:
6536 ln -s ../man7/undocumented.7.gz \
6537 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6539 This manpage claims that the lack of a manpage has been
6540 reported as a bug, so you may only do this if it really has
6541 (you can report it yourself, if you like). Do not close the
6542 bug report until a proper manpage is available.</p>
6545 You may forward a complaint about a missing manpage to the
6546 upstream authors, and mark the bug as forwarded in the
6547 Debian bug tracking system. Even though the GNU Project do
6548 not in general consider the lack of a manpage to be a bug,
6549 we do--if they tell you that they don't consider it a bug
6550 you should leave the bug in our bug tracking system open
6554 Manual pages should be installed compressed using <tt>gzip
6558 If one manpage needs to be accessible via several names it
6559 is better to use a symbolic link than the <tt>.so</tt>
6560 feature, but there is no need to fiddle with the relevant
6561 parts of the upstream source to change from <tt>.so</tt> to
6562 symlinks--don't do it unless it's easy. You should not create hard
6563 links in the manual page directories, nor put
6564 absolute filenames in <tt>.so</tt> directives. The filename
6565 in a <tt>.so</tt> in a manpage should be relative to the
6566 base of the manpage tree (usually
6567 <tt>/usr/share/man</tt>).</p></sect>
6571 <heading>Info documents</heading>
6574 Info documents should be installed in <tt>/usr/share/info</tt>.
6575 They should be compressed with <tt>gzip -9</tt>.</p>
6578 Your package should call <prgn>install-info</prgn> to update the Info
6580 file, in its post-installation script:
6582 install-info --quiet --section Development Development \
6583 /usr/share/info/foobar.info
6587 It is a good idea to specify a section for the location of
6588 your program; this is done with the <tt>--section</tt>
6589 switch. To determine which section to use, you should look
6590 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6591 relevant (or create a new section if none of the current
6592 sections are relevant). Note that the <tt>--section</tt>
6593 flag takes two arguments; the first is a regular expression
6594 to match (case-insensitively) against an existing section,
6595 the second is used when creating a new one.</p>
6598 You should remove the entries in the pre-removal script:
6600 install-info --quiet --remove /usr/share/info/foobar.info
6604 If <prgn>install-info</prgn> cannot find a description entry
6605 in the Info file you must supply one. See <manref
6606 name="install-info" section="8"> for details.</p>
6610 <heading>Additional documentation</heading>
6613 Any additional documentation that comes with the package may
6614 be installed at the discretion of the package maintainer.
6615 Text documentation should be installed in a directory
6616 <tt>/usr/share/doc/<var>package</var></tt>, where
6617 <var>package</var> is the name of the package, and
6618 compressed with <tt>gzip -9</tt> unless it is small.</p>
6621 If a package comes with large amounts of documentation which
6622 many users of the package will not require you should create
6623 a separate binary package to contain it, so that it does not
6624 take up disk space on the machines of users who do not need
6625 or want it installed.</p>
6628 It is often a good idea to put text information files
6629 (<tt>README</tt>s, changelogs, and so forth) that come with
6630 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6631 in the binary package. However, you don't need to install
6632 the instructions for building and installing the package, of
6636 Files in <tt>/usr/share/doc</tt> should not be referenced by
6637 any program, and the system administrator should be able to
6638 delete them without causing any programs to break. Any files
6639 that are referenced by programs but are also useful as
6640 standalone documentation should be installed under
6641 <tt>/usr/share/<package>/</tt> and symlinked in
6642 <tt>/usr/share/doc/<package>/</tt>.
6648 <heading>Accessing the documentation</heading>
6651 Former Debian releases placed all additional documentation
6652 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6654 <tt>/usr/share/doc/<var>package</var></tt>, each package
6655 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6656 that points to the new location of its documentation in
6657 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6658 symlinks will be removed in the future, but they have to be
6659 there for compatibility reasons until all packages have
6660 moved and the policy is changed accordingly.</footnote>.
6661 The symlink must be created when the package is installed;
6662 it cannot be contained in the package itself due to problems
6663 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6664 this is to put the following in the package's
6665 <prgn>postinst</prgn>:
6667 if [ "$1" = "configure" ]; then
6668 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6669 -a -d /usr/share/doc/#PACKAGE# ]; then
6670 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6674 And the following in the package's <prgn>prerm</prgn>:
6676 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6677 -a -L /usr/doc/#PACKAGE# ]; then
6678 rm -f /usr/doc/#PACKAGE#
6685 <heading>Preferred documentation formats</heading>
6688 The unification of Debian documentation is being carried out
6692 If your package comes with extensive documentation in a
6693 mark up format that can be converted to various other formats
6694 you should if possible ship HTML versions in a binary
6695 package, in the directory
6696 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6699 <p>The rationale: The important thing here is that HTML
6700 docs should be available in <em>some</em> package, not
6701 necessarily in the main binary package, though. </p>
6706 Other formats such as PostScript may be provided at your
6710 <sect id="copyrightfile">
6711 <heading>Copyright information</heading>
6714 Every package must be accompanied by a verbatim copy of its
6715 copyright and distribution license in the file
6716 /usr/share/doc/<package-name>/copyright. This file must
6717 neither be compressed nor be a symbolic link.</p>
6720 In addition, the copyright file must say where the upstream
6721 sources (if any) were obtained, and should explain briefly what
6722 modifications were made in the Debian version of the package
6723 compared to the upstream one. It should name the original
6724 authors of the package and the Debian maintainer(s) who were
6725 involved with its creation.</p>
6728 A copy of the file which will be installed in
6729 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6730 in <tt>debian/copyright</tt>.</p>
6734 /usr/share/doc/<package-name> may be a symbolic link to a
6735 directory in /usr/share/doc only if two packages both come from
6736 the same source and the first package has a "Depends"
6737 relationship on the second. These rules are important
6738 because copyrights must be extractable by mechanical
6742 Packages distributed under the UCB BSD license, the Artistic
6743 license, the GNU GPL, and the GNU LGPL should refer to the
6744 files /usr/share/common-licenses/BSD,
6745 /usr/share/common-licenses/Artistic,
6746 /usr/share/common-licenses/GPL, and
6747 /usr/share/common-licenses/LGPL.
6750 Why "licenses" and not "copyright"? Because
6751 <tt>/usr/doc/copyright</tt> used to contain all the
6752 copyright files, plus the four common licenses GPL,
6753 LGPL, Artistic and BSD. Now individual copyright files
6754 for packages are no longer in a common directory. Once
6755 <tt>/usr/doc/copyright</tt> is almost empty it makes
6756 sense to rename "copyright" to "licenses"
6759 Why "common-licenses" and not "licenses"? Because if I
6760 put just "licenses" I'm sure I will receive a bug report
6761 saying "license foo is not included in the licenses
6762 directory. They are not all the licenses, just a few
6763 common ones. I could use /usr/share/doc/common-licenses
6764 but I think this is too long, and, after all, the GPL
6765 does not "document" anything, it is merely a license.
6771 You should not use the copyright file as a general <tt>README</tt>
6772 file. If your package has such a file it should be
6773 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6774 <tt>README.Debian</tt> or some other appropriate place.</p>
6778 <heading>Examples</heading>
6781 Any examples (configurations, source files, whatever),
6782 should be installed in a directory
6783 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6784 files should not be referenced by any program--they're there
6785 for the benefit of the system administrator and users, as
6786 documentation only. Architecture-specific example files
6787 should be installed in a directory
6788 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6789 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6790 to files in it. Or the latter directory may be a symlink to
6794 <sect id="instchangelog">
6795 <heading>Changelog files</heading>
6798 Packages that are not Debian-native must contain a copy of
6799 <tt>debian/changelog</tt> file from the Debian source tree
6800 in <tt>/usr/share/doc/<var>package</var></tt> as
6801 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6802 available, it should be accessible as
6803 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6804 plain text. If the upstream changelog is distributed in
6805 HTML, it should be made available in that form as
6806 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6807 and the <tt>changelog.gz</tt> should be generated using, eg,
6808 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6809 do not already conform to this naming convention, then this
6810 may be achieved either by renaming the files, or adding a
6811 symbolic link, at the maintainer's discretion.
6814 Rationale: People should not have to look into two
6815 places for upstream changelogs merely because they are
6823 All these files should be installed compressed using <tt>gzip -9</tt>,
6824 as they will become large with time even if they start out
6829 If the package has only one changelog which is used both as
6830 the Debian changelog and the upstream one because there is
6831 no separate upstream maintainer then that changelog should
6832 usually be installed as
6833 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6834 there is a separate upstream maintainer, but no upstream
6835 changelog, then the Debian changelog should still be called
6836 <tt>changelog.Debian.gz</tt>.</p>