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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
2174 It has a special format which allows the package building
2175 tools to discover which version of the package is being
2176 built and find out other release-specific information.
2180 That format is a series of entries like this:
2182 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2184 * <var>change details</var>
2185 <var>more change details</var>
2186 * <var>even more change details</var>
2188 -- <var>maintainer name and email address</var> <var>date</var>
2193 <var>package</var> and <var>version</var> are the source
2194 package name and version number.
2198 <var>distribution(s)</var> lists the distributions where
2199 this version should be installed when it is uploaded - it
2200 is copied to the <tt>Distribution</tt> field in the
2201 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2205 <var>urgency</var> is the value for the <tt>Urgency</tt>
2206 field in the <tt>.changes</tt> file for the upload. It is
2207 not possible to specify an urgency containing commas; commas
2208 are used to separate
2209 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2210 <prgn>dpkg</prgn> changelog format (though there is
2211 currently only one useful <var>keyword</var>,
2216 The change details may in fact be any series of lines
2217 starting with at least two spaces, but conventionally each
2218 change starts with an asterisk and a separating space and
2219 continuation lines are indented so as to bring them in
2220 line with the start of the text above. Blank lines may be
2221 used here to separate groups of changes, if desired.
2225 The maintainer name and email address need <em>not</em>
2226 necessarily be those of the usual package maintainer.
2227 They should be the details of the person doing
2228 <em>this</em> version. The information here will be
2229 copied to the <tt>.changes</tt> file, and then later used
2230 to send an acknowledgement when the upload has been
2235 The <var>date</var> should be in RFC822 format
2238 This is generated by the <prgn>822-date</prgn>
2241 </footnote>; it should include the time zone specified
2242 numerically, with the time zone name or abbreviation
2243 optionally present as a comment.
2247 The first `title' line with the package name should start
2248 at the left hand margin; the `trailer' line with the
2249 maintainer and date details should be preceded by exactly
2250 one space. The maintainer details and the date must be
2251 separated by exactly two spaces.
2254 <sect1><heading>Defining alternative changelog formats</heading>
2257 It is possible to use a different format to the standard
2258 one, by providing a parser for the format you wish to
2262 A changelog parser must not interact with the user at
2268 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2269 and variable substitutions </heading>
2272 When <prgn>dpkg-gencontrol</prgn>,
2273 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2274 generate control files they do variable substitutions on
2275 their output just before writing it. Variable
2276 substitutions have the form
2277 <tt>${<var>variable-name</var>}</tt>. The optional file
2278 <tt>debian/substvars</tt> contains variable substitutions
2279 to be used; variables can also be set directly from
2280 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2281 source packaging commands, and certain predefined
2282 variables are available.
2286 The is usually generated and modified dynamically by
2287 <tt>debian/rules</tt> targets; in this case it must be
2288 removed by the <prgn>clean</prgn> target.
2292 See <manref name="dpkg-source" section="1"> for full
2293 details about source variable substitutions, including the
2294 format of <tt>debian/substvars</tt>.</p>
2297 <sect id="debianfiles"><heading><tt>debian/files</tt>
2301 This file is not a permanent part of the source tree; it
2302 is used while building packages to record which files are
2303 being generated. <prgn>dpkg-genchanges</prgn> uses it
2304 when it generates a <tt>.changes</tt> file.
2308 It should not exist in a shipped source package, and so it
2309 (and any backup files or temporary files such as
2313 <tt>files.new</tt> is used as a temporary file by
2314 <prgn>dpkg-gencontrol</prgn> and
2315 <prgn>dpkg-distaddfile</prgn> - they write a new
2316 version of <tt>files</tt> here before renaming it,
2317 to avoid leaving a corrupted copy if an error
2320 </footnote>) should be removed by the
2321 <prgn>clean</prgn> target. It may also be wise to
2322 ensure a fresh start by emptying or removing it at the
2323 start of the <prgn>binary</prgn> target.
2327 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2328 for the <tt>.deb</tt> file that will be created by
2329 <prgn>dpkg-deb</prgn> from the control file that it
2330 generates, so for most packages all that needs to be done
2331 with this file is to delete it in <prgn>clean</prgn>.
2335 If a package upload includes files besides the source
2336 package and any binary packages whose control files were
2337 made with <prgn>dpkg-gencontrol</prgn> then they should be
2338 placed in the parent of the package's top-level directory
2339 and <prgn>dpkg-distaddfile</prgn> should be called to add
2340 the file to the list in <tt>debian/files</tt>.</p>
2343 <sect id="restrictions"><heading>Restrictions on objects in source packages
2347 The source package may not contain any hard links
2350 This is not currently detected when building source
2351 packages, but only when extracting
2357 Hard links may be permitted at some point in the
2358 future, but would require a fair amount of
2361 </footnote>, device special files, sockets or setuid or
2365 Setgid directories are allowed.
2370 <sect id="descriptions"><heading>Descriptions of packages - the
2371 <tt>Description</tt> field </heading>
2374 The description is intended to describe the program to a user
2375 who has never met it before so that they know whether they
2376 want to install it. It should also give information about the
2377 significant dependencies and conflicts between this package
2378 and others, so that the user knows why these dependencies and
2379 conflicts have been declared.
2382 <sect1><heading>Notes about writing descriptions
2386 The single line synopsis should be kept brief - certainly
2387 under 80 characters.
2391 Do not include the package name in the synopsis line. The
2392 display software knows how to display this already, and you
2393 do not need to state it. Remember that in many situations
2394 the user may only see the synopsis line - make it as
2395 informative as you can.
2399 Do not try to continue the single line synopsis into the
2400 extended description. This will not work correctly when
2401 the full description is displayed, and makes no sense
2402 where only the summary (the single line synopsis) is
2407 The extended description should describe what the package
2408 does and how it relates to the rest of the system (in terms
2409 of, for example, which subsystem it is which part of).
2413 The description field needs to make sense to anyone, even
2414 people who have no idea about any of the things the
2418 The blurb that comes with a program in its
2419 announcements and/or <prgn>README</prgn> files is
2420 rarely suitable for use in a description. It is
2421 usually aimed at people who are already in the
2422 community where the package is used.
2428 Put important information first, both in the synopsis and
2429 extended description. Sometimes only the first part of the
2430 synopsis or of the description will be displayed. You can
2431 assume that there will usually be a way to see the whole
2432 extended description.
2436 You may include information about dependencies and so forth
2437 in the extended description, if you wish.
2441 Do not use tab characters. Their effect is not predictable.
2449 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2450 and installation procedure
2453 <sect><heading>Introduction to package maintainer scripts
2457 It is possible to supply scripts as part of a package which
2458 the package management system will run for you when your
2459 package is installed, upgraded or removed.
2463 These scripts should be the files <tt>preinst</tt>,
2464 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2465 control area of the package. They must be proper executable
2466 files; if they are scripts (which is recommended) they must
2467 start with the usual <tt>#!</tt> convention. They should be
2468 readable and executable by anyone, and not world-writable.
2472 The package management system looks at the exit status from
2473 these scripts. It is important that they exit with a
2474 non-zero status if there is an error, so that the package
2475 management system can stop its processing. For shell
2476 scripts this means that you <em>almost always</em> need to
2477 use <tt>set -e</tt> (this is usually true when writing shell
2478 scripts, in fact). It is also important, of course, that
2479 they don't exit with a non-zero status if everything went
2484 It is necessary for the error recovery procedures that the
2485 scripts be idempotent: i.e., invoking the same script several
2486 times in the same situation should do no harm. If the first
2487 call failed, or aborted half way through for some reason,
2488 the second call should merely do the things that were left
2489 undone the first time, if any, and exit with a success
2494 When a package is upgraded a combination of the scripts from
2495 the old and new packages is called in amongst the other
2496 steps of the upgrade procedure. If your scripts are going
2497 to be at all complicated you need to be aware of this, and
2498 may need to check the arguments to your scripts.
2502 Broadly speaking the <prgn>preinst</prgn> is called before
2503 (a particular version of) a package is installed, and the
2504 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2505 before (a version of) a package is removed and the
2506 <prgn>postrm</prgn> afterwards.
2509 <p> Programs called from maintainer scripts should not
2510 normally have a path prepended to them. Before installation
2511 is started the package management system checks to see if
2512 the programs <prgn>ldconfig</prgn>,
2513 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2514 and <prgn>update-rc.d</prgn> can be found via the
2515 <tt>PATH</tt> environment variable. Those programs, and any
2516 other program that one would expect to on the <tt>PATH</tt>,
2517 should thus be invoked without an absolute
2518 pathname. Maintainer scripts should also not reset the
2519 <tt>PATH</tt>, though they might choose to modify it by pre-
2520 or appending package-specific directories. These
2521 considerations really apply to all shell scripts.</p>
2524 <heading>Maintainer scripts Idempotency</heading>
2527 It is very important to make maintainer scripts
2531 That means that if it runs successfully or fails
2532 and then you call it again it doesn't bomb out,
2533 but just ensures that everything is the way it
2536 </footnote> This is so that if an error occurs, the
2537 user interrupts <prgn>dpkg</prgn> or some other
2538 unforeseen circumstance happens you don't leave the
2539 user with a badly-broken package.
2543 <heading>Controlling terminal for maintainer scripts</heading>
2546 The maintainer scripts are guaranteed to run with a
2547 controlling terminal and can interact with the user.
2548 If they need to prompt for passwords, do full-screen
2549 interaction or something similar you should do these
2550 things to and from <tt>/dev/tty</tt>, since
2551 <prgn>dpkg</prgn> will at some point redirect scripts'
2552 standard input and output so that it can log the
2553 installation process. Likewise, because these scripts
2554 may be executed with standard output redirected into a
2555 pipe for logging purposes, Perl scripts should set
2556 unbuffered output by setting <tt>$|=1</tt> so that the
2557 output is printed immediately rather than being
2562 Each script should return a zero exit status for
2563 success, or a nonzero one for failure.
2567 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2572 <list compact="compact">
2574 <p><var>new-preinst</var> <tt>install</tt></p>
2577 <p><var>new-preinst</var> <tt>install</tt>
2578 <var>old-version</var></p>
2581 <p><var>new-preinst</var> <tt>upgrade</tt>
2582 <var>old-version</var></p>
2585 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2586 <var>new-version</var>
2592 <list compact="compact">
2594 <p><var>postinst</var> <tt>configure</tt>
2595 <var>most-recently-configured-version</var></p>
2598 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2599 <var>new version</var></p>
2602 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2603 <tt>in-favour</tt> <var>package</var>
2604 <var>new-version</var></p>
2608 <var>deconfigured's-postinst</var>
2609 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2610 <var>failed-install-package</var> <var>version</var>
2611 <tt>removing</tt> <var>conflicting-package</var>
2618 <list compact="compact">
2620 <p><var>prerm</var> <tt>remove</tt></p>
2623 <p><var>old-prerm</var> <tt>upgrade</tt>
2624 <var>new-version</var></p>
2627 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2628 <var>old-version</var></p>
2631 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2632 <tt>in-favour</tt> <var>package</var>
2633 <var>new-version</var></p>
2637 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2638 <tt>in-favour</tt> <var>package-being-installed</var>
2639 <var>version</var> <tt>removing</tt>
2640 <var>conflicting-package</var>
2647 <list compact="compact">
2649 <p><var>postrm</var> <tt>remove</tt></p>
2652 <p><var>postrm</var> <tt>purge</tt></p>
2656 <var>old-postrm</var> <tt>upgrade</tt>
2657 <var>new-version</var></p>
2660 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2661 <var>old-version</var></p>
2664 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2667 <p><var>new-postrm</var> <tt>abort-install</tt>
2668 <var>old-version</var></p>
2671 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2672 <var>old-version</var></p>
2676 <var>disappearer's-postrm</var> <tt>disappear</tt>
2677 <var>overwriter</var>
2678 <var>overwriter-version</var></p></item>
2683 <sect id="unpackphase"><heading>Details of unpack phase of
2684 installation or upgrade
2688 The procedure on installation/upgrade/overwrite/disappear
2689 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2690 stage of <tt>dpkg --install</tt>) is as follows. In each
2691 case if an error occurs the actions are, in general, run
2692 backwards - this means that the maintainer scripts are run
2693 with different arguments in reverse order. These are the
2694 `error unwind' calls listed below.
2701 <p>If a version of the package is already
2704 <var>old-prerm</var> upgrade <var>new-version</var>
2709 If the script runs but exits with a non-zero
2710 exit status, <prgn>dpkg</prgn> will attempt:
2712 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2714 Error unwind, for both the above cases:
2716 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2724 <p>If a `conflicting' package is being removed at the same time:
2728 If any packages depended on that conflicting
2729 package and <tt>--auto-deconfigure</tt> is
2730 specified, call, for each such package:
2732 <var>deconfigured's-prerm</var> deconfigure \
2733 in-favour <var>package-being-installed</var> <var>version</var> \
2734 removing <var>conflicting-package</var> <var>version</var>
2738 <var>deconfigured's-postinst</var> abort-deconfigure \
2739 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2740 removing <var>conflicting-package</var> <var>version</var>
2742 The deconfigured packages are marked as
2743 requiring configuration, so that if
2744 <tt>--install</tt> is used they will be
2745 configured again if possible.</p>
2748 <p>To prepare for removal of the conflicting package, call:
2750 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2754 <var>conflictor's-postinst</var> abort-remove \
2755 in-favour <var>package</var> <var>new-version</var>
2766 <p>If the package is being upgraded, call:
2768 <var>new-preinst</var> upgrade <var>old-version</var>
2773 Otherwise, if the package had some configuration
2774 files from a previous version installed (i.e., it
2775 is in the `configuration files only' state):
2777 <var>new-preinst</var> install <var>old-version</var>
2781 <p>Otherwise (i.e., the package was completely purged):
2783 <var>new-preinst</var> install
2785 Error unwind versions, respectively:
2787 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2788 <var>new-postrm</var> abort-install <var>old-version</var>
2789 <var>new-postrm</var> abort-install
2799 The new package's files are unpacked, overwriting any
2800 that may be on the system already, for example any
2801 from the old version of the same package or from
2802 another package (backups of the old files are left
2803 around, and if anything goes wrong the package
2804 management system will attempt to put them back as
2805 part of the error unwind).
2809 It is an error for a package to contains files which
2810 are on the system in another package, unless
2811 <tt>Replaces</tt> is used (see <ref id="replaces">).
2812 Currently the <tt>--force-overwrite</tt> flag is
2813 enabled, downgrading it to a warning, but this may not
2818 It is a more serious error for a package to contain a
2819 plain file or other kind of non-directory where another
2820 package has a directory (again, unless
2821 <tt>Replaces</tt> is used). This error can be
2822 overridden if desired using
2823 <tt>--force-overwrite-dir</tt>, but this is not
2828 Packages which overwrite each other's files produce
2829 behavior which though deterministic is hard for the
2830 system administrator to understand. It can easily
2831 lead to `missing' programs if, for example, a package
2832 is installed which overwrites a file from another
2833 package, and is then removed again.
2836 Part of the problem is due to what is arguably a
2837 bug in <prgn>dpkg</prgn>.
2843 A directory will never be replaced by a symbolic links
2844 to a directory or vice versa; instead, the existing
2845 state (symlink or not) will be left alone and
2846 <prgn>dpkg</prgn> will follow the symlink if there is
2854 <p>If the package is being upgraded, call
2856 <var>old-postrm</var> upgrade <var>new-version</var>
2860 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2862 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2864 Error unwind, for both cases:
2866 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2872 This is the point of no return - if
2873 <prgn>dpkg</prgn> gets this far, it won't back off
2874 past this point if an error occurs. This will
2875 leave the package in a fairly bad state, which
2876 will require a successful re-installation to clear
2877 up, but it's when <prgn>dpkg</prgn> starts doing
2878 things that are irreversible.
2883 Any files which were in the old version of the package
2884 but not in the new are removed.</p>
2887 <p>The new file list replaces the old.</p>
2890 <p>The new maintainer scripts replace the old.</p>
2894 <p>Any packages all of whose files have been overwritten during the
2895 installation, and which aren't required for
2896 dependencies, are considered to have been removed.
2897 For each such package,
2900 <p><prgn>dpkg</prgn> calls:
2902 <var>disappearer's-postrm</var> disappear \
2903 <var>overwriter</var> <var>overwriter-version</var>
2908 <p>The package's maintainer scripts are removed.
2913 It is noted in the status database as being in a
2914 sane state, namely not installed (any conffiles
2915 it may have are ignored, rather than being
2916 removed by <prgn>dpkg</prgn>). Note that
2917 disappearing packages do not have their prerm
2918 called, because <prgn>dpkg</prgn> doesn't know
2919 in advance that the package is going to
2928 Any files in the package we're unpacking that are also
2929 listed in the file lists of other packages are removed
2930 from those lists. (This will lobotomize the file list
2931 of the `conflicting' package if there is one.)
2936 The backup files made during installation, above, are
2943 The new package's status is now sane, and recorded as
2944 `unpacked'. Here is another point of no return - if
2945 the conflicting package's removal fails we do not
2946 unwind the rest of the installation; the conflicting
2947 package is left in a half-removed limbo.
2952 If there was a conflicting package we go and do the
2953 removal actions (described below), starting with the
2954 removal of the conflicting package's files (any that
2955 are also in the package being installed have already
2956 been removed from the conflicting package's file list,
2957 and so do not get removed now).
2964 <sect><heading>Details of configuration</heading>
2967 When we configure a package (this happens with <tt>dpkg
2968 --install</tt>, or with <tt>--configure</tt>), we first
2969 update the conffiles and then call:
2971 <var>postinst</var> configure <var>most-recently-configured-version</var>
2976 No attempt is made to unwind after errors during
2981 If there is no most recently configured version
2982 <prgn>dpkg</prgn> will pass a null argument; older versions
2983 of dpkg may pass <tt><unknown></tt> (including the
2984 angle brackets) in this case. Even older ones do not pass a
2985 second argument at all, under any circumstances.
2989 <sect><heading>Details of removal and/or configuration purging
2997 <var>prerm</var> remove
3003 The package's files are removed (except conffiles).
3008 <var>postrm</var> remove
3012 <p>All the maintainer scripts except the postrm are removed.
3016 If we aren't purging the package we stop here. Note
3017 that packages which have no postrm and no conffiles
3018 are automatically purged when removed, as there is no
3019 difference except for the <prgn>dpkg</prgn>
3024 The conffiles and any backup files (<tt>~</tt>-files,
3025 <tt>#*#</tt> files, <tt>%</tt>-files,
3026 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3030 <var>postrm</var> purge
3034 <p>The package's file list is removed.</p>
3037 No attempt is made to unwind after errors during
3043 <chapt id="relationships"><heading>Declaring relationships between
3047 Packages can declare in their control file that they have
3048 certain relationships to other packages - for example, that
3049 they may not be installed at the same time as certain other
3050 packages, and/or that they depend on the presence of others,
3051 or that they should overwrite files in certain other packages
3056 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3057 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3058 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3062 Source packages may declare relationships to binary packages,
3063 saying that they require certain binary packages to be
3064 installed or absent at the time of building the package.
3068 This is done using the <tt>Build-Depends</tt>,
3069 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3070 <tt>Build-Conflicts-Indep</tt> control file fields.
3073 <sect id="depsyntax"><heading>Syntax of relationship fields
3077 These fields all have a uniform syntax. They are a list of
3078 package names separated by commas.
3082 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3083 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3084 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3085 control file fields of the package, which declare
3086 dependencies on other packages, the package names listed may
3087 also include lists of alternative package names, separated
3088 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3089 a case, the presence of any one of the alternative packages
3090 is installed, that part of the dependency is considered to
3095 All the fields except <tt>Provides</tt> may restrict their
3096 applicability to particular versions of each named package.
3097 This is done in parentheses after each individual package
3098 name; the parentheses should contain a relation from the
3099 list below followed by a version number, in the format
3100 described in <ref id="versions">.
3104 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3105 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3106 strictly earlier, earlier or equal, exactly equal, later or
3107 equal and strictly later, respectively. The forms
3108 <tt><</tt> and <tt>></tt> were used to mean
3109 earlier/later or equal, rather than strictly earlier/later,
3110 so they should not appear in new packages (though
3111 <prgn>dpkg</prgn> still supports them).
3115 Whitespace may appear at any point in the version
3116 specification, and must appear where it's necessary to
3117 disambiguate; it is not otherwise significant. For
3118 consistency and in case of future changes to
3119 <prgn>dpkg</prgn> it is recommended that a single space be
3120 used after a version relationship and before a version
3121 number; it is usual also to put a single space after each
3122 comma, on either side of each vertical bar, and before each
3131 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3136 All fields that specify build-time relationships
3137 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3138 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3139 may be restricted to a certain set of architectures. This
3140 is done in brackets after each individual package name and
3141 the optional version specification. The brackets enclose a
3142 list of Debian architecture names separated by whitespace.
3143 Exclamation marks may be prepended to each of the names.
3144 (It is not permitted for some names to be prepended with
3145 exclamation marks and others not.) If the current Debian
3146 host architecture is not in this list and there are no
3147 exclamation marks in the list, or it is in the list with a
3148 prepended exclamation mark, the package name and the
3149 associated version specification are ignored completely for
3150 the purposes of defining the relationships.
3157 Build-Depends-Indep: texinfo
3158 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3159 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3165 <heading>Binary Dependencies - <tt>Depends</tt>,
3166 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3167 <tt>Pre-Depends</tt>
3171 These five fields are used to declare a dependency
3172 relationship by one package on another. They appear in the
3173 depending package's control file.
3177 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3178 (discussed below) take effect <em>only</em> when a package
3179 is to be configured. They do not prevent a package being on
3180 the system in an unconfigured state while its dependencies
3181 are unsatisfied, and it is possible to replace a package
3182 whose dependencies are satisfied and which is properly
3183 installed with a different version whose dependencies are
3184 not and cannot be satisfied; when this is done the depending
3185 package will be left unconfigured (since attempts to
3186 configure it will give errors) and will not function
3191 For this reason packages in an installation run are usually
3192 all unpacked first and all configured later; this gives
3193 later versions of packages with dependencies on later
3194 versions of other packages the opportunity to have their
3195 dependencies satisfied.
3199 Thus <tt>Depends</tt> allows package maintainers to impose
3200 an order in which packages should be configured.
3202 <tag><tt>Depends</tt></tag>
3205 <p>This declares an absolute dependency.
3209 The <tt>Depends</tt> field should be used if the
3210 depended-on package is required for the depending
3211 package to provide a significant amount of
3215 <tag><tt>Recommends</tt></tag>
3217 <p>This declares a strong, but not absolute, dependency.
3221 The <tt>Recommends</tt> field should list packages
3222 that would be found together with this one in all but
3223 unusual installations.</p>
3226 <tag><tt>Suggests</tt></tag>
3230 This is used to declare that one package may be more
3231 useful with one or more others. Using this field
3232 tells the packaging system and the user that the
3233 listed packages are related to this one and can
3234 perhaps enhance its usefulness, but that installing
3235 this one without them is perfectly reasonable.
3239 <tag><tt>Enhances</tt></tag>
3242 This field is similar to Suggests but works in the
3243 opposite direction. It is used to declare that a
3244 package can enhance the functionality of another
3249 <tag><tt>Pre-Depends</tt></tag>
3253 This field is like <tt>Depends</tt>, except that it
3254 also forces <prgn>dpkg</prgn> to complete installation
3255 of the packages named before even starting the
3256 installation of the package which declares the
3261 <tt>Pre-Depends</tt> should be used sparingly,
3262 preferably only by packages whose premature upgrade or
3263 installation would hamper the ability of the system to
3264 continue with any upgrade that might be in progress.
3268 When the package declaring it is being configured, a
3269 <tt>Pre-Dependency</tt> will be considered satisfied
3270 only if the depending package has been correctly
3271 configured, just as if an ordinary <tt>Depends</tt>
3276 However, when a package declaring a Pre-dependency is
3277 being unpacked the predependency can be satisfied even
3278 if the depended-on package(s) are only unpacked or
3279 half-configured, provided that they have been
3280 configured correctly at some point in the past (and
3281 not removed or partially removed since). In this case
3282 both the previously-configured and currently unpacked
3283 or half-configured versions must satisfy any version
3284 clause in the <tt>Pre-Depends</tt> field.
3290 When selecting which level of dependency to use you should
3291 consider how important the depended-on package is to the
3292 functionality of the one declaring the dependency. Some
3293 packages are composed of components of varying degrees of
3294 importance. Such a package should list using
3295 <tt>Depends</tt> the package(s) which are required by the
3296 more important components. The other components'
3297 requirements may be mentioned as Suggestions or
3298 Recommendations, as appropriate to the components' relative
3303 <sect id="conflicts"><heading>Alternative binary packages -
3304 <tt>Conflicts</tt> and <tt>Replaces</tt>
3308 When one binary package declares a conflict with another
3309 <prgn>dpkg</prgn> will refuse to allow them to be installed
3310 on the system at the same time.
3314 If one package is to be installed, the other must be removed
3315 first - if the package being installed is marked as
3316 replacing (<ref id="replaces">) the one on the system, or
3317 the one on the system is marked as deselected, or both
3318 packages are marked <tt>Essential</tt>, then
3319 <prgn>dpkg</prgn> will automatically remove the package
3320 which is causing the conflict, otherwise it will halt the
3321 installation of the new package with an error. This
3322 mechanism specifically doesn't work when the installed
3323 package is <tt>Essential</tt>, but the new package is not.
3328 A package will not cause a conflict merely because its
3329 configuration files are still installed; it must be at least
3334 A special exception is made for packages which declare a
3335 conflict with their own package name, or with a virtual
3336 package which they provide (see below): this does not
3337 prevent their installation, and allows a package to conflict
3338 with others providing a replacement for it. You use this
3339 feature when you want the package in question to be the only
3340 package providing something.
3344 A <tt>Conflicts</tt> entry should almost never have an
3345 `earlier than' version clause. This would prevent
3346 <prgn>dpkg</prgn> from upgrading or installing the package
3347 which declared such a conflict until the upgrade or removal
3348 of the conflicted-with package had been completed.
3352 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3356 As well as the names of actual (`concrete') packages, the
3357 package relationship fields <tt>Depends</tt>,
3358 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3359 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3360 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3361 mention virtual packages.
3365 A virtual package is one which appears in the
3366 <tt>Provides</tt> control file field of another package.
3367 The effect is as if the package(s) which provide a
3368 particular virtual package name had been listed by name
3369 everywhere the virtual package name appears.
3373 If there are both a real and a virtual package of the same
3374 name then the dependency may be satisfied (or the conflict
3375 caused) by either the real package or any of the virtual
3376 packages which provide it. This is so that, for example,
3382 and someone else releases an xemacs package they can say
3386 </example> and all will work in the interim (until a purely
3387 virtual package name is decided on and the <tt>emacs</tt>
3388 and <tt>vm</tt> packages are changed to use it).
3392 If a dependency or a conflict has a version number attached
3393 then only real packages will be considered to see whether
3394 the relationship is satisfied (or the prohibition violated,
3395 for a conflict) - it is assumed that a real package which
3396 provides the virtual package is not of the `right' version.
3397 So, a <tt>Provides</tt> field may not contain version
3398 numbers, and the version number of the concrete package
3399 which provides a particular virtual package will not be
3400 looked at when considering a dependency on or conflict with
3401 the virtual package name.
3405 It is likely that the ability will be added in a future
3406 release of <prgn>dpkg</prgn> to specify a version number for
3407 each virtual package it provides. This feature is not yet
3408 present, however, and is expected to be used only
3413 If you want to specify which of a set of real packages should be the
3414 default to satisfy a particular dependency on a virtual package, you
3415 should list the real package as an alternative before the virtual.
3420 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3421 files and replacing packages
3425 The <tt>Replaces</tt> control file field has two purposes,
3426 which come into play in different situations.
3430 Virtual packages (<ref id="virtual">) are not considered
3431 when looking at a <tt>Replaces</tt> field - the packages
3432 declared as being replaced must be mentioned by their real
3436 <sect1><heading>Overwriting files in other packages
3440 Firstly, as mentioned before, it is usually an error for a
3441 package to contain files which are on the system in
3442 another package, though currently the
3443 <tt>--force-overwrite</tt> flag is enabled by default,
3444 downgrading the error to a warning,
3448 If the overwriting package declares that it replaces the
3449 one containing the file being overwritten then
3450 <prgn>dpkg</prgn> will proceed, and replace the file from
3451 the old package with that from the new. The file will no
3452 longer be listed as `owned' by the old package.
3456 If a package is completely replaced in this way, so that
3457 <prgn>dpkg</prgn> does not know of any files it still
3458 contains, it is considered to have disappeared. It will
3459 be marked as not wanted on the system (selected for
3460 removal) and not installed. Any conffiles details noted
3461 in the package will be ignored, as they will have been
3462 taken over by the replacing package(s). The package's
3463 <prgn>postrm</prgn> script will be run to allow the
3464 package to do any final cleanup required. See <ref
3465 id="mscriptsinstact">.
3469 In the future <prgn>dpkg</prgn> will discard files which
3470 would overwrite those from an already installed package
3471 which declares that it replaces the package being
3472 installed. This is so that you can install an older
3473 version of a package without problems.
3477 This usage of <tt>Replaces</tt> only takes effect when
3478 both packages are at least partially on the system at
3479 once, so that it can only happen if they do not conflict
3480 or if the conflict has been overridden.</p>
3483 <sect1><heading>Replacing whole packages, forcing their
3488 Secondly, <tt>Replaces</tt> allows the packaging system to
3489 resolve which package should be removed when there is a
3490 conflict - see <ref id="conflicts">. This usage only
3491 takes effect when the two packages <em>do</em> conflict,
3492 so that the two effects do not interfere with each other.
3497 <sect><heading>Relationships between source and binary packages -
3498 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3499 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3503 A source package may declare a dependency or a conflict on a
3504 binary package. This is done with the control file fields
3505 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3506 <tt>Build-Conflicts</tt>, and
3507 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3508 the dependencies and conflicts they define must be satisfied
3509 (as defined earlier for binary packages), when one of the
3510 targets in <tt>debian/rules</tt> that the particular field
3511 applies to is invoked.
3514 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3517 The <tt>Build-Depends</tt> and
3518 <tt>Build-Conflicts</tt> fields apply to the targets
3519 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3520 and <tt>binary-indep</tt>.
3523 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3526 The <tt>Build-Depends-Indep</tt> and
3527 <tt>Build-Conflicts-Indep</tt> fields apply to the
3528 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3539 <chapt id="conffiles"><heading>Configuration file handling
3543 <prgn>dpkg</prgn> can do a certain amount of automatic
3544 handling of package configuration files.
3548 Whether this mechanism is appropriate depends on a number of
3549 factors, but basically there are two approaches to any
3550 particular configuration file.
3554 The easy method is to ship a best-effort configuration in the
3555 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3556 handle updates. If the user is unlikely to want to edit the
3557 file, but you need them to be able to without losing their
3558 changes, and a new package with a changed version of the file
3559 is only released infrequently, this is a good approach.
3563 The hard method is to build the configuration file from
3564 scratch in the <prgn>postinst</prgn> script, and to take the
3565 responsibility for fixing any mistakes made in earlier
3566 versions of the package automatically. This will be
3567 appropriate if the file is likely to need to be different on
3572 <chapt id="sharedlibs"><heading>Shared libraries
3576 Packages containing shared libraries must be constructed with
3577 a little care to make sure that the shared library is always
3578 available. This is especially important for packages whose
3579 shared libraries are vitally important, such as the libc.
3583 Firstly, your package should install the shared libraries
3584 under their normal names. For example, the
3585 <prgn>libgdbm1</prgn> package should install
3586 <tt>libgdbm.so.1.7.3</tt> as
3587 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3588 renamed or re-linked by any prerm or postrm scripts;
3589 <prgn>dpkg</prgn> will take care of renaming things safely
3590 without affecting running programs, and attempts to interfere
3591 with this are likely to lead to problems.
3595 Secondly, your package should include the symlink that
3596 <prgn>ldconfig</prgn> would create for the shared libraries.
3597 For example, the <prgn>libgdbm1</prgn> package should include
3598 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3599 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3600 <prgn>ld.so</prgn> can find the library in between the time
3601 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3602 in the <prgn>postinst</prgn> script. Furthermore, older
3603 versions of the package management system required the library
3604 must be placed before the symlink pointing to it in the
3605 <tt>.deb</tt> file. This is so that by the time
3606 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3607 the previous symlink pointing at an older version of the
3608 library) the new shared library is already in place.
3609 Unfortunately, this was not not always possible, since it
3610 highly depends on the behavior of the file system. Some
3611 file systems (such as reiserfs) will reorder the files so it
3612 doesn't matter in what order you create them. Starting with
3613 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3614 files itself when building a package.
3618 Thirdly, the development package should contain a symlink for
3619 the shared library without a version number. For example, the
3620 <tt>libgdbm1-dev</tt> package should include a symlink from
3621 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3622 symlink is needed by <prgn>ld</prgn> when compiling packages
3623 as it will only look for <tt>libgdm.so</tt> and
3624 <tt>libgdm.a</tt> when compiling dynamically or statically,
3629 Any package installing shared libraries in a directory that's listed
3630 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3631 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3632 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3633 script if and only if the first argument is `configure'. However, it
3634 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3635 scripts in the case where the package is being upgraded (see <ref
3636 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3637 that <prgn>dpkg</prgn> uses for the files while it is
3638 installing them and will make the shared library links point
3639 to them, just before <prgn>dpkg</prgn> continues the
3640 installation and removes the links!
3643 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3647 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3648 required when your package provides shared libraries.
3652 Each line is of the form:
3654 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3659 <var>library-name</var> is the name of the shared library,
3660 for example <tt>libc5</tt>.
3664 <var>version-or-soname</var> is the soname of the library -
3665 i.e., the thing that must exactly match for the library to be
3666 recognized by <prgn>ld.so</prgn>. Usually this is the major
3667 version number of the library.
3671 <var>dependencies</var> has the same syntax as a dependency
3672 field in a binary package control file. It should give
3673 details of which package(s) are required to satisfy a binary
3674 built against the version of the library contained in the
3675 package. See <ref id="depsyntax">.
3679 For example, if the package <tt>foo</tt> contains
3680 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3681 <tt>libfoo.so.1</tt>, and the first version of the package
3682 which contained a minor number of at least <tt>2.3</tt> was
3683 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3686 libfoo 1 foo (>= 1.2.3-1)
3691 The version-specific dependency is to avoid warnings from
3692 <prgn>ld.so</prgn> about using older shared libraries with
3696 <sect><heading>Further Technical information on
3697 <tt>shlibs</tt></heading>
3699 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3703 The <tt>debian/shlibs</tt> file provides a way of checking
3704 for shared library dependencies on packaged binaries.
3705 They are intended to be used by package maintainers to
3706 make their lives easier.
3710 Other <tt>shlibs</tt> files that exist on a Debian system are
3712 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3713 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3714 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3715 <item> <p><tt>debian/shlibs.local</tt></p></item>
3717 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3718 creating a binary package.</p>
3721 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3725 <prgn>dpkg-shlibdeps</prgn>
3726 determines the shared libraries directly
3729 It used to do this by calling <prgn>ldd</prgn>, but it
3730 now calls <prgn>objdump</prgn> to do this. This
3731 requires a couple of changes in the way that packages
3735 A binary <tt>foo</tt> directly uses a library
3736 <tt>libbar</tt> if it is linked with that
3737 library. Other libraries that are needed by
3738 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3739 and the dynamic linker will load them automatically
3740 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3741 lists all of the libraries used, both directly and
3742 indirectly; but <prgn>objdump</prgn> only lists the
3743 directly linked libraries. A package only needs to
3744 depend on the libraries it is directly linked to,
3745 since the dependencies for those libraries should
3746 automatically pull in the other libraries.
3749 This change does mean a change in the way packages are
3750 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3751 only run on binaries. But since we will now rely on the
3752 libraries depending on the libraries they themselves
3753 need, the packages containing those libraries will
3754 need to run <prgn>dpkg-shlibdeps</prgn> on the
3758 A good example where this would help us is the current
3759 mess with multiple version of the <tt>mesa</tt>
3760 library. With the <prgn>ldd</prgn>-based system, every
3761 package that uses <tt>mesa</tt> needs to add a
3762 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3763 to handle the glide <tt>mesa</tt> variant. With an
3764 <prgn>objdump</prgn>-based system this isn't necessary
3765 anymore and would have saved everyone a lot of work.
3768 Another example: we could update <tt>libimlib</tt>
3769 with a new version that supports a new graphics format
3770 called dgf. If we use the old <prgn>ldd</prgn> method,
3771 every package that uses <tt>libimlib</tt> would need
3772 to be recompiled so it would also depend on
3773 <tt>libdgf</tt> or it wouldn't run due to missing
3774 symbols. However with the new system, packages using
3775 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3776 having the dependency on <tt>libdgf</tt> and wouldn't
3780 used by the compiled binaries and libraries passed through
3781 on its command line.
3785 For each shared library linked to,
3786 <prgn>dpkg-shlibdeps</prgn> needs to know
3787 <list compact="compact">
3788 <item><p>the package containing the library, and</p></item>
3789 <item><p>the library version number,</p></item>
3791 and it scans the following files in this order:
3792 <enumlist compact="compact">
3793 <item><p><tt>debian/shlibs.local</tt></p></item>
3794 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3795 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3796 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3801 <sect1><heading><em>Who</em> maintains the various
3802 <tt>shlibs</tt> files?
3806 <list compact="compact">
3808 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3813 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3814 - the maintainer of each package</p>
3818 <tt>/etc/dpkg/shlibs.override</tt> - the local
3819 system administrator</p>
3822 <p><tt>debian/shlibs.local</tt> - the maintainer of
3827 The <tt>shlibs.default</tt> file is managed by
3828 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3829 that are provided by <prgn>dpkg</prgn> are just there to
3830 fix things until the shared library packages all have
3831 <tt>shlibs</tt> files.
3835 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3836 the <tt>shlibs</tt> files
3839 <sect2><heading>If your package doesn't provide a shared
3844 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3845 <tt>debian/rules</tt> file. If your package contains
3846 only binaries (e.g. no scripts) use:
3848 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3850 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3851 done. If it does complain you might need to create your
3852 own <tt>debian/shlibs.local</tt> file.</p>
3855 <sect2><heading>If your package provides a shared library
3859 Create a <tt>debian/shlibs</tt> file and let
3860 <tt>debian/rules</tt> install it in the control area:
3862 install -m644 debian/shlibs debian/tmp/DEBIAN
3864 If your package contains additional binaries see above.
3869 <sect1><heading><em>How</em> to write
3870 <tt>debian/shlibs.local</tt>
3874 This file is intended only as a <em>temporary</em> fix if
3875 your binaries depend on a library which doesn't provide
3876 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3880 Let's assume you are packaging a binary <tt>foo</tt>. Your
3881 output in building the package might look like this.
3884 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3885 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3886 libc.so.6 => /lib/libc.so.6 (0x40114000)
3887 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3889 And when you ran <prgn>dpkg-shlibdeps</prgn>
3891 $ dpkg-shlibdeps -O foo
3892 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3893 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3894 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3896 The <prgn>foo</prgn> binary depends on the
3897 <prgn>libbar</prgn> shared library, but no package seems
3898 to provide a <tt>*.shlibs</tt> file in
3899 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3905 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3906 bar1: /usr/X11R6/lib/libbar.so.1.0
3907 $ dpkg -s bar1 | grep Version
3910 This tells us that the <prgn>bar1</prgn> package, version
3911 1.0-1 is the one we are using. Now we can create our own
3912 <tt>debian/shlibs.local</tt> to temporarily fix the above
3913 problem. Include the following line into your
3914 <tt>debian/shlibs.local</tt> file.
3916 libbar 1 bar1 (>= 1.0-1)
3918 Now your package build should work. As soon as the
3919 maintainer of <prgn>libbar1</prgn> provides a
3920 <tt>shlibs</tt> file, you can remove your
3921 <tt>debian/shlibs.local</tt> file.
3927 <chapt><heading>The Operating System</heading>
3931 <heading>File system hierarchy</heading>
3935 <heading>Linux File system Structure</heading>
3938 The location of all installed files and directories must
3939 comply with the Linux File system Hierarchy Standard
3940 (FHS). The latest version of this document can be found
3941 alongside this manual or on
3942 <url id="http://www.pathname.com/fhs/">.
3943 Specific questions about following the standard may be
3944 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3945 Quinlan, the FHS coordinator, at
3946 <email>quinlan@pathname.com</email>.</p></sect1>
3950 <heading>Site-specific programs</heading>
3953 As mandated by the FHS, packages must not place any
3954 files in <tt>/usr/local</tt>, either by putting them in
3955 the file system archive to be unpacked by <prgn>dpkg</prgn>
3956 or by manipulating them in their maintainer scripts.</p>
3959 However, the package may create empty directories below
3960 <tt>/usr/local</tt> so that the system administrator knows
3961 where to place site-specific files. These directories
3962 should be removed on package removal if they are
3966 Note, that this applies only to directories <em>below</em>
3967 <tt>/usr/local</tt>, not <em>in</em>
3968 <tt>/usr/local</tt>. Packages must not create sub-directories
3969 in the directory <tt>/usr/local</tt> itself, except those listed in
3970 FHS, section 4.5. However, you may create directories
3971 below them as you wish. You must not remove any of the
3972 directories listed in 4.5, even if you created them.</p>
3975 Since <tt>/usr/local</tt> can be mounted read-only from a
3976 remote server, these directories must be created and
3977 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3978 maintainer scripts. These scripts must not fail if either
3979 of these operations fail. (In the future, it will be
3980 possible to tell <prgn>dpkg</prgn> not to unpack files
3981 matching certain patterns, so that the directories can be
3982 included in the <tt>.deb</tt> packages and system
3983 administrators who do not wish these directories in
3984 /usr/local do not need to have them.)</p>
3987 For example, the <prgn>emacs</prgn> package will contain
3989 mkdir -p /usr/local/lib/emacs/site-lisp || true
3991 in the <tt>postinst</tt> script, and
3993 rmdir /usr/local/lib/emacs/site-lisp || true
3994 rmdir /usr/local/lib/emacs || true
3996 in the <tt>prerm</tt> script.</p>
3999 If you do create a directory in <tt>/usr/local</tt> for
4000 local additions to a package, you should ensure that
4001 settings in <tt>/usr/local</tt> take precedence over the
4002 equivalents in <tt>/usr</tt>.</p>
4005 However, because '/usr/local' and its contents are for
4006 exclusive use of the local administrator, a package must
4007 not rely on the presence or absence of files or
4008 directories in '/usr/local' for normal operation.</p>
4011 The <tt>/usr/local</tt> directory itself and all the
4012 subdirectories created by the package should (by default) have
4013 permissions 2775 (group-writable and set-group-id) and be
4014 owned by <tt>root.staff</tt>.</p>
4019 <heading>Users and groups</heading>
4022 The Debian system can be configured to use either plain or
4023 shadow passwords.</p>
4026 Some user ids (UIDs) and group ids (GIDs) are reserved
4027 globally for use by certain packages. Because some packages
4028 need to include files which are owned by these users or
4029 groups, or need the ids compiled into binaries, these ids
4030 must be used on any Debian system only for the purpose for
4031 which they are allocated. This is a serious restriction, and
4032 we should avoid getting in the way of local administration
4033 policies. In particular, many sites allocate users and/or
4034 local system groups starting at 100.</p>
4037 Apart from this we should have dynamically allocated ids,
4038 which should by default be arranged in some sensible
4039 order--but the behavior should be configurable.</p>
4042 Packages other than <tt>base-passwd</tt> must not modify
4043 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4044 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4047 The UID and GID ranges are as follows:
4052 Globally allocated by the Debian project, the
4053 same on every Debian system. These ids will appear in
4054 the <tt>passwd</tt> and <tt>group</tt> files of all
4055 Debian systems, new ids in this range being added
4056 automatically as the <tt>base-passwd</tt> package is
4060 Packages which need a single statically allocated uid
4061 or gid should use one of these; their maintainers
4062 should ask the <tt>base-passwd</tt> maintainer for
4069 Dynamically allocated system users and groups.
4070 Packages which need a user or group, but can have this
4071 user or group allocated dynamically and differently on
4072 each system, should use `<tt>adduser --system</tt>' to
4073 create the group and/or user. <prgn>adduser</prgn>
4074 will check for the existence of the user or group, and
4075 if necessary choose an unused id based on the ranges
4076 specified in <tt>adduser.conf</tt>.</p></item>
4079 <tag>1000-29999:</tag>
4082 Dynamically allocated user accounts. By default
4083 <prgn>adduser</prgn> will choose UIDs and GIDs for
4084 user accounts in this range, though
4085 <tt>adduser.conf</tt> may be used to modify this
4089 <tag>30000-59999:</tag>
4091 <p>Reserved.</p></item>
4094 <tag>60000-64999:</tag>
4097 Globally allocated by the Debian project, but only
4098 created on demand. The ids are allocated centrally and
4099 statically, but the actual accounts are only created
4100 on users' systems on demand.</p>
4103 These ids are for packages which are obscure or which
4104 require many statically-allocated ids. These packages
4105 should check for and create the accounts in
4106 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4107 <prgn>adduser</prgn> if it has this facility) if
4108 necessary. Packages which are likely to require
4109 further allocations should have a `hole' left after
4110 them in the allocation, to give them room to
4114 <tag>65000-65533:</tag>
4116 <p>Reserved.</p></item>
4121 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4122 to the group `<tt>nogroup</tt>.'</p></item>
4128 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4129 because it is the error return sentinel value.</p>
4134 <sect id="sysvinit">
4135 <heading>System run levels</heading>
4138 <sect1 id="/etc/init.d">
4139 <heading>Introduction</heading>
4142 The <tt>/etc/init.d</tt> directory contains the scripts
4143 executed by <prgn>init</prgn> at boot time and when init
4144 state (or `runlevel') is changed (see <manref name="init"
4148 There are at least two different, yet functionally
4149 equivalent, ways of handling these scripts. For the sake
4150 of simplicity, this document describes only the symbolic
4151 link method. However, it must not be assumed by maintainer
4152 scripts that this method is being used, and any automated
4153 manipulation of the various runlevel behaviours by
4154 maintainer scripts must be performed using `update-rc.d'
4155 as described below and not by manually installing or
4156 removing symlinks. For information on the
4157 implementation details of the other method, implemented in
4158 the <tt>file-rc</tt> package, please refer to the
4159 documentation of that package.</p>
4162 These scripts are referenced by symbolic links in
4163 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4164 changing runlevels, <prgn>init</prgn> looks in the
4165 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4166 it should execute, where <var>n</var> is the runlevel that
4167 is being changed to, or `S' for the boot-up scripts.</p>
4170 The names of the links all have the form
4171 <tt>S<var>mm</var><var>script</var></tt> or
4172 <tt>K<var>mm</var><var>script</var></tt> where
4173 <var>mm</var> is a two-digit number and <var>script</var>
4174 is the name of the script (this should be the same as the
4175 name of the actual script in <tt>/etc/init.d</tt>.</p>
4178 When <prgn>init</prgn> changes runlevel first the targets
4179 of the links whose names starting with a <tt>K</tt> are
4180 executed, each with the single argument <tt>stop</tt>,
4181 followed by the scripts prefixed with an <tt>S</tt>, each
4182 with the single argument <tt>start</tt>. The <tt>K</tt>
4183 links are responsible for killing services and the
4184 <tt>S</tt> link for starting services upon entering the
4188 For example, if we are changing from runlevel 2 to
4189 runlevel 3, init will first execute all of the <tt>K</tt>
4190 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4191 all of the <tt>S</tt> prefixed scripts. The links
4192 starting with <tt>K</tt> will cause the referred-to file
4193 to be executed with an argument of <tt>stop</tt>, and the
4194 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4197 The two-digit number <var>mm</var> is used to decide which
4198 order to start and stop things in--low-numbered links have
4199 their scripts run first. For example, the <tt>K20</tt>
4200 scripts will be executed before the <tt>K30</tt> scripts.
4201 This is used when a certain service must be started before
4202 another. For example, the name server <prgn>bind</prgn>
4203 might need to be started before the news server
4204 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4205 access lists. In this case, the script that starts
4206 <prgn>bind</prgn> would have a lower number than the
4207 script that starts <prgn>inn</prgn> so that it runs first:
4216 <heading>Writing the scripts</heading>
4219 Packages that include daemons for system services should
4220 place scripts in <tt>/etc/init.d</tt> to start or stop
4221 services at boot time or during a change of runlevel.
4222 These scripts should be named
4223 <tt>/etc/init.d/<var>package</var></tt>, and they should
4224 accept one argument, saying what to do:
4227 <tag><tt>start</tt></tag>
4228 <item><p>start the service,</p></item>
4230 <tag><tt>stop</tt></tag>
4231 <item><p>stop the service,</p></item>
4233 <tag><tt>restart</tt></tag>
4234 <item><p>stop and restart the service,</p></item>
4236 <tag><tt>reload</tt></tag>
4237 <item><p>cause the configuration of the service to be
4238 reloaded without actually stopping and restarting
4239 the service,</p></item>
4241 <tag><tt>force-reload</tt></tag> <item><p>cause the
4242 configuration to be reloaded if the service supports
4243 this, otherwise restart the service.</p></item>
4246 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4247 <tt>force-reload</tt> options should be supported by all
4248 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4249 option is optional.</p>
4252 The <tt>init.d</tt> scripts should ensure that they will
4253 behave sensibly if invoked with <tt>start</tt> when the
4254 service is already running, or with <tt>stop</tt> when it
4255 isn't, and that they don't kill unfortunately-named user
4256 processes. The best way to achieve this is usually to use
4257 <prgn>start-stop-daemon</prgn>.</p>
4260 If a service reloads its configuration automatically (as
4261 in the case of <prgn>cron</prgn>, for example), the
4262 <tt>reload</tt> option of the <tt>init.d</tt> script
4263 should behave as if the configuration has been reloaded
4267 These scripts should not fail obscurely when the
4268 configuration files remain but the package has been
4269 removed, as configuration files remain on the system after
4270 the package has been removed. Only when <prgn>dpkg</prgn>
4271 is executed with the <tt>--purge</tt> option will
4272 configuration files be removed. In particular, the init
4273 script itself is usually a configuration file (see
4274 <ref id="init.d notes">), and will remain on the system if
4275 the package is removed but not purged. Therefore, you
4276 should include a <tt>test</tt> statement at the top of the
4279 test -f <var>program-executed-later-in-script</var> || exit 0
4283 Often there are some values in the `<tt>init.d</tt>'
4284 scripts that a system administrator will frequently want
4285 to change. While the scripts are frequently conffiles,
4286 modifying them requires that the administrator merge in
4287 their changes each time the package is upgraded and the
4288 conffile changes. To ease the burden on the system
4289 administrator, such configurable values should not be
4290 placed directly in the script. Instead, they should be
4291 placed in a file in `<tt>/etc/default</tt>', which
4292 typically will have the same base name as the
4293 `<tt>init.d</tt>' script. This extra file can be sourced
4294 by the script when the script runs. It must contain only
4295 variable settings and comments.
4299 To ensure that vital configurable values are always
4300 available, the `<tt>init.d</tt>' script should set default
4301 values for each of the shell variables it uses before
4302 sourcing the <tt>/etc/default/</tt> file. Also, since the
4303 `<tt>/etc/default/</tt>' file is often a conffile, the
4304 `<tt>init.d</tt>' script must behave sensibly without
4305 failing if it is deleted.
4311 <heading>Managing the links</heading>
4314 The program <prgn>update-rc.d</prgn> is provided to make
4315 it easier for package maintainers to arrange for the
4316 proper creation and removal of
4317 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4318 functional equivalent if another method is being used.
4319 This may be used by maintainers in their packages'
4320 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4323 You must use this script to make changes to
4324 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4325 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4326 in the actual archive or manually create or remove the
4327 symbolic links in maintainer scripts. (The latter will
4328 fail if an alternative method of maintaining runlevel
4329 information is being used.)</p>
4332 By default <prgn>update-rc.d</prgn> will start services in
4333 each of the multi-user state runlevels (2, 3, 4, and 5)
4334 and stop them in the halt runlevel (0), the single-user
4335 runlevel (1) and the reboot runlevel (6). The system
4336 administrator will have the opportunity to customize
4337 runlevels by either running <prgn>update-rc.d</prgn>, by
4338 simply adding, moving, or removing the symbolic links in
4339 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4340 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4341 <tt>file-rc</tt> method is being used.</p>
4344 To get the default behavior for your package, put in your
4345 <tt>postinst</tt> script
4347 update-rc.d <var>package</var> defaults >/dev/null
4349 and in your <tt>postrm</tt>
4351 if [ purge = "$1" ]; then
4352 update-rc.d <var>package</var> remove >/dev/null
4357 This will use a default sequence number of 20. If it does
4358 not matter when or in which order the script is run, use
4359 this default. If it does, then you should talk to the
4360 maintainer of the <prgn>sysvinit</prgn> package or post to
4361 <tt>debian-devel</tt>, and they will help you choose a
4365 For more information about using <tt>update-rc.d</tt>,
4366 please consult its manpage <manref name="update-rc.d"
4367 section="8">.</p></sect1>
4371 <heading>Boot-time initialization</heading>
4374 There used to be another directory, <tt>/etc/rc.boot</tt>,
4375 which contained scripts which were run once per machine
4376 boot. This has been deprecated in favour of links from
4377 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4378 described in <ref id="/etc/init.d">. Packages must not
4379 place files in <tt>/etc/rc.boot</tt>.</p>
4381 <sect1 id="init.d notes">
4382 <heading>Notes</heading>
4385 <em>Do not</em> include the
4386 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4387 <tt>.deb</tt> file system archive! <em>This will cause
4388 problems!</em> You must create them with
4389 <prgn>update-rc.d</prgn>, as above.</p>
4392 <em>Do not</em> include the
4393 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4394 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4395 problems!</em> You should, however, treat the
4396 <tt>/etc/init.d</tt> scripts as configuration files,
4397 either by marking them as conffiles or managing them
4398 correctly in the maintainer scripts (see
4399 <ref id="config files">). (This is important since we want
4400 to give the local system administrator the chance to adapt
4401 the scripts to the local system--e.g., to disable a
4402 service without de-installing the package, or to specify
4403 some special command line options when starting a
4404 service--while making sure her changes aren't lost during
4405 the next package upgrade.)</p>
4409 <heading>Example</heading>
4412 The <prgn>bind</prgn> DNS (nameserver) package wants to
4413 make sure that the nameserver is running in multiuser
4414 runlevels, and is properly shut down with the system. It
4415 puts a script in <tt>/etc/init.d</tt>, naming the script
4416 appropriately <tt>bind</tt>. As you can see, the script
4417 interprets the argument <tt>reload</tt> to send the
4418 nameserver a <tt>HUP</tt> signal (causing it to reload its
4419 configuration); this way the user can say
4420 <tt>/etc/init.d/bind reload</tt> to reload the name
4421 server. The script has one configurable value, which can
4422 be used to pass parameters to the named program at
4430 # Original version by Robert Leslie
4431 # <rob@mars.org>, edited by iwj and cs
4433 test -x /usr/sbin/named || exit 0
4435 # Source defaults file.
4437 if [ -f /etc/default/bind ]; then
4444 echo -n "Starting domain name service: named"
4445 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4450 echo -n "Stopping domain name service: named"
4451 start-stop-daemon --stop --quiet \
4452 --pidfile /var/run/named.pid --exec /usr/sbin/named
4456 echo -n "Restarting domain name service: named"
4457 start-stop-daemon --stop --quiet \
4458 --pidfile /var/run/named.pid --exec /usr/sbin/named
4459 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4463 force-reload|reload)
4464 echo -n "Reloading configuration of domain name service: named"
4465 start-stop-daemon --stop --signal 1 --quiet \
4466 --pidfile /var/run/named.pid --exec /usr/sbin/named
4470 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4480 Complementing the above init script is a file
4481 '<tt>/etc/default/bind</tt>', which contains configurable
4482 parameters used by the script.
4486 # Specified parameters to pass to named. See named(8).
4487 # You may uncomment the following line, and edit to taste.
4493 Another example on which to base your <tt>/etc/init.d</tt>
4494 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4497 If this package is happy with the default setup from
4498 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4499 and having named running in all runlevels, it can say in
4500 its <tt>postinst</tt>:
4502 update-rc.d bind defaults >/dev/null
4504 And in its <tt>postrm</tt>, to remove the links when the
4507 if [ purge = "$1" ]; then
4508 update-rc.d bind remove >/dev/null
4514 <heading>Cron jobs</heading>
4517 Packages must not modify the configuration file
4518 <tt>/etc/crontab</tt>, and they must not modify the files in
4519 <tt>/var/spool/cron/crontabs</tt>.</p>
4522 If a package wants to install a job that has to be executed
4523 via cron, it should place a file with the name of the
4524 package in one of the following directories:
4530 As these directory names imply, the files within them are
4531 executed on a daily, weekly, or monthly basis,
4532 respectively. The exact times are listed in
4533 <tt>/etc/crontab</tt>.</p>
4536 All files installed in any of these directories must be
4537 scripts (shell scripts, Perl scripts, etc.) so that they can
4538 easily be modified by the local system administrator. In
4539 addition, they should be treated as configuration files.</p>
4542 If a certain job has to be executed more frequently than
4543 daily, the package should install a file
4544 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4545 the same syntax as <tt>/etc/crontab</tt> and is processed by
4546 <prgn>cron</prgn> automatically. The file must also be
4547 treated as a configuration file. (Note, that entries in the
4548 <tt>/etc/cron.d</tt> directory are not handled by
4549 <prgn>anacron</prgn>. Thus, you should only use this
4550 directory for jobs which may be skipped if the system is not
4554 The scripts or crontab entries in these directories should
4555 check if all necessary programs are installed before they
4556 try to execute them. Otherwise, problems will arise when a
4557 package was removed but not purged since configuration files
4558 are kept on the system in this situation.</p>
4562 <heading>Console messages</heading>
4565 This section describes different formats for messages
4566 written to standard output by the <tt>/etc/init.d</tt>
4567 scripts. The intent is to improve the consistency of
4568 Debian's startup and shutdown look and feel.</p>
4571 Please look very careful at the details. We want to get the
4572 messages to look exactly the same way concerning spaces,
4573 punctuation, and case of letters.</p>
4576 Here is a list of overall rules that you should use when you
4577 create output messages. They can be useful if you have a
4578 non-standard message that isn't covered in the sections
4585 Every message should cover one line, start with a
4586 capital letter and end with a period `.'.</p></item>
4591 If you want to express that the computer is working on
4592 something (performing a specific task, not starting or
4593 stopping a program), we use an ``ellipsis'', namely
4594 three dots `...'. Note that we don't insert spaces in
4595 front of or behind the dots. If the task has been
4596 completed we write `done.' and a line feed.</p></item>
4601 Design your messages as if the computer is telling you
4602 what he is doing (let him be polite :-) but don't
4603 mention ``him'' directly. For example, if you think
4606 I'm starting network daemons: nfsd mountd.
4610 Starting network daemons: nfsd mountd.
4611 </example></p></item>
4615 The following formats should be used</p>
4620 <p>when daemons get started.</p>
4623 Use this format if your script starts one or more
4624 daemons. The output should look like this (a single
4625 line, no leading spaces):
4627 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4629 The <description> should describe the subsystem
4630 the daemon or set of daemons are part of, while
4631 <daemon-1> up to <daemon-n> denote each
4632 daemon's name (typically the file name of the
4636 For example, the output of /etc/init.d/lpd would look like:
4638 Starting printer spooler: lpd.
4642 This can be achieved by saying
4644 echo -n "Starting printer spooler: lpd"
4645 start-stop-daemon --start --quiet lpd
4648 in the script. If you have more than one daemon to
4649 start, you should do the following:
4651 echo -n "Starting remote file system services:"
4652 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4653 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4654 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4657 This makes it possible for the user to see what takes
4658 so long and when the final daemon has been
4659 started. You should be careful where to put spaces: In the
4660 example above the system administrator can easily
4661 comment out a line if he don't wants to start a
4662 specific daemon, while the displayed message still
4663 looks good.</p></item>
4667 <p>when something needs to be configured.</p>
4670 If you have to set up different parameters of the
4671 system upon boot up, you should use this format:
4673 Setting <parameter> to `<value>'.
4677 You can use the following echo statement to get the quotes right:
4679 echo "Setting DNS domainname to \`"value"'."
4683 Note that the left quotation mark (`) is different
4684 from the right (').</p></item>
4687 <p>when a daemon is stopped.</p>
4690 When you stop a daemon you should issue a message
4691 similar to the startup message, except that `Starting'
4692 is replaced with `Stopping'.</p>
4695 So stopping the printer daemon will like like this:
4697 Stopping printer spooler: lpd.
4698 </example></p></item>
4701 <p>when something is executed.</p>
4704 There are several examples where you have to run a
4705 program at system startup or shutdown to perform a
4706 specific task. For example, setting the system's clock
4707 via `netdate' or killing all processes when the system
4708 comes down. Your message should like this:
4710 Doing something very useful...done.
4712 You should print the `done.' right after the job has been completed,
4713 so that the user gets informed why he has to wait. You can get this
4716 echo -n "Doing something very useful..."
4720 in your script.</p></item>
4723 <p>when the configuration is reloaded.</p>
4726 When a daemon is forced to reload its configuration
4727 files you should use the following format:
4729 Reloading <daemon's-name> configuration...done.
4730 </example></p></item>
4733 <p>when none of the above rules apply.</p>
4736 If you have to print a message that doesn't fit into
4737 the styles described above, you can use something
4738 appropriate, but please have a look at the overall
4739 rules listed above.</p></item>
4744 <heading>Menus</heading>
4747 Menu entries should follow the current menu policy as
4748 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4749 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4750 or your local mirror. In addition, it is included in the
4751 <tt>debian-policy</tt> package.
4755 The Debian <tt>menu</tt> packages provides a unique
4756 interface between packages providing applications and
4757 documents, and <em>menu programs</em> (either X window
4758 managers or text-based menu programs as
4759 <prgn>pdmenu</prgn>).</p>
4762 All packages that provide applications that need not be
4763 passed any special command line arguments for normal
4764 operation should register a menu entry for those
4765 applications, so that users of the <tt>menu</tt> package
4766 will automatically get menu entries in their window
4767 managers, as well in shells like <tt>pdmenu</tt>.</p>
4770 Please refer to the <em>Debian Menu System</em> document
4771 that comes with the <tt>menu</tt> package for information
4772 about how to register your applications and web
4778 <heading>Multimedia handlers</heading>
4781 Packages which provide the ability to view/show/play,
4782 compose, edit or print MIME types should register themselves
4783 as such following the current MIME support policy as defined
4784 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4785 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4786 or your local mirror. In addition, it is included in the
4787 <tt>debian-policy</tt> package.
4791 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4792 mechanism for encoding files and data streams and providing
4793 meta-information about them, in particular their type (e.g.
4794 audio or video) and format (e.g. PNG, HTML, MP3).
4798 Registration of MIME type handlers allows programs like mail
4799 user agents and web browsers to to invoke these handlers to
4800 view, edit or display MIME types they don't support
4806 <heading>Keyboard configuration</heading>
4809 To achieve a consistent keyboard configuration (i.e., all
4810 applications interpret a keyboard event the same way) all
4811 programs in the Debian distribution must be configured to
4812 comply with the following guidelines.</p>
4815 Here is a list that contains certain keys and their interpretation:
4818 <tag><tt><--</tt></tag>
4819 <item><p>delete the character to the left of the cursor</p></item>
4821 <tag><tt>Delete</tt></tag>
4822 <item><p>delete the character to the right of the cursor</p></item>
4824 <tag><tt>Control+H</tt></tag>
4825 <item><p>emacs: the help prefix</p></item>
4828 The interpretation of any keyboard events should be independent
4829 of the terminal that's used, be it a virtual console, an X
4830 terminal emulator, an rlogin/telnet session, etc.</p>
4833 The following list explains how the different programs
4834 should be set up to achieve this:</p>
4837 <list compact="compact">
4838 <item><p>`<tt><--</tt>' generates KB_Backspace in
4841 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4845 X translations are set up to make KB_Backspace
4846 generate ASCII DEL, and to make KB_Delete generate
4847 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4848 the `delete character' key). This must be done by
4849 loading the resources using xrdb on all local X
4850 displays, not using the application defaults, so that
4851 the translation resources used correspond to the
4852 xmodmap settings.</p></item>
4856 The Linux console is configured to make
4857 `<tt><--</tt>' generate DEL, and `Delete' generate
4858 <tt>ESC [ 3 ~</tt> (this is the case at the
4862 X applications are configured so that Backspace
4863 deletes left, and Delete deletes right. Motif
4864 applications already work like this.</p></item>
4866 <item><p>stty erase <tt>^?</tt> .</p></item>
4869 The `xterm' terminfo entry should have <tt>ESC [ 3
4870 ~</tt> for kdch1, just like TERM=linux and
4871 TERM=vt220.</p></item>
4874 Emacs is programmed to map KB_Backspace or the `stty
4875 erase' character to delete-backward-char, and
4876 KB_Delete or kdch1 to delete-forward-char, and
4877 <tt>^H</tt> to help as always.</p></item>
4880 Other applications use the `stty erase' character and
4881 kdch1 for the two delete keys, with ASCII DEL being
4882 `delete previous character' and kdch1 being `delete
4883 character under cursor'.</p></item>
4887 This will solve the problem except for:</p>
4890 <list compact="compact">
4892 Some terminals have a <tt><--</tt> key that cannot
4893 be made to produce anything except <tt>^H</tt>. On
4894 these terminals Emacs help will be unavailable on
4895 <tt>^H</tt> (assuming that the `stty erase' character
4896 takes precedence in Emacs, and has been set
4897 correctly). M-x help or F1 (if available) can be used
4901 Some operating systems use <tt>^H</tt> for stty erase.
4902 However, modern telnet versions and all rlogin
4903 versions propagate stty settings, and almost all UNIX
4904 versions honour stty erase. Where the stty settings
4905 are not propagated correctly things can be made to
4906 work by using stty manually.</p></item>
4909 Some systems (including previous Debian versions) use
4910 xmodmap to arrange for both <tt><--</tt> and Delete
4911 to generate KB_Delete. We can change the behavior
4912 of their X clients via the same X resources that we
4913 use to do it for our own, or have our clients be
4914 configured via their resources when things are the
4915 other way around. On displays configured like this
4916 Delete will not work, but <tt><--</tt>
4920 Some operating systems have different kdch1 settings
4921 in their terminfo for xterm and others. On these
4922 systems the Delete key will not work correctly when
4923 you log in from a system conforming to our policy, but
4924 <tt><--</tt> will.</p></item>
4931 <heading>Environment variables</heading>
4934 A program must not depend on environment variables to get
4935 reasonable defaults. (That's because these environment
4936 variables would have to be set in a system-wide
4937 configuration file like /etc/profile, which is not supported
4941 If a program usually depends on environment variables for its
4942 configuration, the program should be changed to fall back to
4943 a reasonable default configuration if these environment
4944 variables are not present. If this cannot be done easily
4945 (e.g., if the source code of a non-free program is not
4946 available), the program must be replaced by a small
4947 `wrapper' shell script which sets the environment variables
4948 if they are not already defined, and calls the original program.</p>
4951 Here is an example of a wrapper script for this purpose:
4955 BAR=${BAR:-/var/lib/fubar}
4957 exec /usr/lib/foo/foo "$@"
4961 Furthermore, as <tt>/etc/profile</tt> is a configuration
4962 file of the <prgn>base-files</prgn> package, other packages must not
4963 put any environment variables or other commands into that
4968 <heading>Files</heading>
4972 <heading>Binaries</heading>
4975 Two different packages must not install programs with
4976 different functionality but with the same filenames. (The
4977 case of two programs having the same functionality but
4978 different implementations is handled via `alternatives.')
4979 If this case happens, one of the programs must be
4980 renamed. The maintainers should report this to the
4981 developers' mailing and try to find a consensus about
4982 which package will have to be renamed. If a consensus can
4983 not be reached, <em>both</em> programs must be
4987 Generally the following compilation parameters should be used:
4990 CFLAGS = -O2 -Wall # sane warning options vary between programs
4992 install -s # (or use strip on the files in debian/tmp)
4996 Note that by default all installed binaries should be stripped,
4997 either by using the <tt>-s</tt> flag to
4998 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4999 the binaries after they have been copied into
5000 <tt>debian/tmp</tt> but before the tree is made into a
5004 The <tt>-N</tt> flag should not be used. On a.out systems
5005 it may have been useful for some very small binaries, but
5006 for ELF it has no good effect.</p>
5009 Debugging symbols are useful for error diagnosis,
5010 investigation of core dumps (which may be submitted by users
5011 in bug reports), or testing and developing the
5012 software. Therefore it is recommended to support building
5013 the package with debugging information through the following
5014 interface: If the environment variable
5015 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5016 <tt>debug</tt>, compile the software with debugging
5017 information (usually this involves adding the <tt>-g</tt>
5018 flag to <tt>CFLAGS</tt>). This allows the generation of a
5019 build tree with debugging information. If the environment
5020 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5021 <tt>nostrip</tt>, do not strip the files at installation
5022 time. This allows one to generate a package with debugging
5023 information included. The following makefile snippet is only
5024 an example of how one may test for either condition:
5027 Rationale: Building by default with -g causes more
5028 wasted CPU cycles since the information is stripped away
5029 anyway. The package can by default build without -g if
5030 it also provides a mechanism to easily be rebuilt with
5031 debugging information. This can be done by providing a
5032 "build-debug" make target, or allowing the user to
5033 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5034 compiling that package.
5036 <p>Now this has several added benefits:
5040 It is actually easier to build debugging bins and
5041 libraries this way (no more editing debian/rules
5042 or similar) since it provides a documented way of
5043 getting this type of build.</p>
5047 There will be much less wasted CPU time for the
5048 autobuilders since not having debugging
5049 information (and hence also not having to strip
5050 it) will increase the speed of compiles. This
5051 skips an entire pass of the compiler.
5062 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5063 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5064 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5065 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5067 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5070 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5071 INSTALL_PROGRAM += -s
5075 Please note that the above example is merely informative,
5076 and is not a policy mandate. You may have to massage this
5077 example in order to make it work for your package.
5082 It is up to the package maintainer to decide what
5083 compilation options are best for the package. Certain
5084 binaries (such as computationally-intensive programs) will
5085 function better with certain flags (<tt>-O3</tt>, for
5086 example); feel free to use them. Please use good judgment
5087 here. Don't use flags for the sake of it; only use them
5088 if there is good reason to do so. Feel free to override
5089 the upstream author's ideas about which compilation
5090 options are best--they are often inappropriate for our
5091 environment.</p></sect>
5095 <heading>Libraries</heading>
5098 All libraries must have a shared version in the lib
5099 package and a static version in the lib-dev package. The
5100 shared version must be compiled with <tt>-fPIC</tt>, and
5101 the static version must not be. In other words, each
5102 <tt>*.c</tt> file will need to be compiled twice.</p>
5105 You must specify the gcc option <tt>-D_REENTRANT</tt>
5106 when building a library (either static or shared) to make
5107 the library compatible with LinuxThreads.</p>
5110 Note that all installed shared libraries should be
5113 strip --strip-unneeded <your-lib>
5115 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5116 only the symbols which aren't needed for relocation
5117 processing.) Shared libraries can function perfectly well
5118 when stripped, since the symbols for dynamic linking are
5119 in a separate part of the ELF object file.</p>
5122 Note that under some circumstances it may be useful to
5123 install a shared library unstripped, for example when
5124 building a separate package to support debugging.
5128 An ever increasing number of packages are using libtool to
5129 do their linking. The latest GNU libtools (>= 1.3a) can take
5130 advantage of the metadata in the installed libtool archive
5131 files (`*.la'). The main advantage of libtool's .la files is
5132 that it allows libtool to store and subsequently access
5133 metadata with respect to the libraries it builds. libtool
5134 will search for those files, which contain a lot of useful
5135 information about a library (e.g. dependency libraries for
5136 static linking). Also, they're <em>essential</em> for
5137 programs using libltdl.
5141 Certainly libtool is fully capable of linking against shared
5142 libraries which don't have .la files, but being a mere shell
5143 script it can add considerably to the build time of a
5144 libtool using package if that shell-script has to derive all
5145 this information from first principles for each library every
5146 time it is linked. With the advent of libtool-1.4 (and to a
5147 lesser extent libtool-1.3), the .la files will also store
5148 information about inter-library dependencies which cannot
5149 necessarily be derived after the .la file is deleted.
5153 Packages that use libtool to create shared libraries should
5154 include the <em>.la</em> files in the <em>-dev</em>
5155 packages, with the exception that if the package relies on
5156 libtool's <em>libltdl</em> library, in which case the .la
5157 files must go in the run-time library package. This is a
5158 good idea in general, and especially for static linking
5163 You must make sure that you use only released versions of
5164 shared libraries to build your packages; otherwise other
5165 users will not be able to run your binaries
5166 properly. Producing source packages that depend on
5167 unreleased compilers is also usually a bad
5174 <heading>Shared libraries</heading>
5177 Packages involving shared libraries should be split up
5178 into several binary packages.</p>
5181 For a straightforward library which has a development
5182 environment and a runtime kit including just shared
5183 libraries you need to create two packages:
5184 <tt><var>libraryname</var><var>soname</var></tt>
5185 (<var>soname</var> is the shared object name of the shared
5186 library--it's the thing that has to match exactly between
5187 building an executable and running it for the dynamic
5188 linker to be able run the program; usually the
5189 <var>soname</var> is the major number of the library) and
5190 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5193 If you prefer only to support one development version at a
5194 time you may name the development package
5195 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5196 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5197 ensure that the user only installs one development version
5198 at a time (after all, different development versions are
5199 likely to have the same header files in them, causing a
5200 filename clash if both are installed). Typically the
5201 development version should also have an exact version
5202 dependency on the runtime library, to make sure that
5203 compilation and linking happens correctly.</p>
5206 Packages which use the shared library should have a
5207 dependency on the name of the shared library package,
5208 <tt><var>libraryname</var><var>soname</var></tt>. When
5209 the <var>soname</var> changes you can have both versions
5210 of the library installed while moving from the old library
5214 If your package has some run-time support programs which
5215 use the shared library you must not put them in
5216 the shared library package. If you do that then you won't
5217 be able to install several versions of the shared library
5218 without getting filename clashes. Instead, either create
5219 a third package for the runtime binaries (this package
5220 might typically be named
5221 <tt><var>libraryname</var>-runtime</tt>--note the absence
5222 of the <var>soname</var> in the package name) or if the
5223 development package is small include them in there.</p>
5226 If you have several shared libraries built from the same
5227 source tree you may lump them all together into a single
5228 shared library package, provided that you change all their
5229 <var>soname</var>s at once (so that you don't get filename
5230 clashes if you try to install different versions of the
5231 combined shared libraries package).</p>
5234 You should follow the directions in the <em>Debian Packaging
5235 Manual</em> for putting the shared library in its package,
5236 and you must include a <tt>shlibs</tt> control area
5237 file with details of the dependencies for packages which
5238 use the library.</p>
5241 Shared libraries should not be installed
5242 executable, since <prgn>ld.so</prgn> does not require this
5243 and trying to execute a shared library results in a core
5248 <heading>Scripts</heading>
5251 All command scripts, including the package maintainer
5252 scripts inside the package and used by <prgn>dpkg</prgn>,
5253 should have a <tt>#!</tt> line naming the shell to be used
5254 to interpret them.</p>
5257 In the case of Perl scripts this should be
5258 <tt>#!/usr/bin/perl</tt>.</p>
5261 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5262 should almost certainly start with <tt>set -e</tt> so that
5263 errors are detected. Every script should use
5264 <tt>set -e</tt> or check the exit status of <em>every</em>
5268 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5269 symbolic link to any POSIX compatible shell, if <tt>echo
5270 -n</tt> does not generate a newline.
5273 Debian policy specifies POSIX behavior for /bin/sh, but
5274 echo -n has widespread use in the Linux community
5275 (including especially debian policy, the linux kernel
5276 source, many debian scripts, etc.). This echo -n
5277 mechanism is valid but not required under POSIX, hence
5278 this explicit addition. Also, rumour has it that this
5279 shall be mandated under the LSB anyway.
5283 specifying `<tt>/bin/sh</tt>' as interpreter should only
5284 use POSIX features. If a script requires non-POSIX
5285 features from the shell interpreter, the appropriate shell
5286 must be specified in the first line of the script (e.g.,
5287 `<tt>#!/bin/bash</tt>') and the package must depend on the
5288 package providing the shell (unless the shell package is
5289 marked `Essential', e.g., in the case of
5294 You may wish to restrict your script to POSIX features when possible so
5295 that it may use <tt>/bin/sh</tt> as its interpreter. If
5296 your script works with <prgn>ash</prgn>, it's probably
5297 POSIX compliant, but if you are in doubt, use
5298 <tt>/bin/bash</tt>.</p>
5301 Perl scripts should check for errors when making any
5302 system calls, including <tt>open</tt>, <tt>print</tt>,
5303 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5306 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5307 as scripting languages. See <em>Csh Programming
5308 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5309 FAQs. It can be found on
5310 <url id="http://language.perl.com/versus/csh.whynot">, or
5311 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5312 or even on <ftpsite>ftp.cpan.org</ftpsite>
5313 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5314 If an upstream package comes with <prgn>csh</prgn> scripts
5315 then you must make sure that they start with
5316 <tt>#!/bin/csh</tt> and make your package depend on the
5317 <prgn>c-shell</prgn> virtual package.</p>
5320 Any scripts which create files in world-writeable
5321 directories (e.g., in <tt>/tmp</tt>) must use a
5322 mechanism which will fail if a file with the same name
5326 The Debian base distribution provides the
5327 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5328 for use by scripts for this purpose.</p></sect>
5332 <heading>Symbolic links</heading>
5335 In general, symbolic links within a top-level directory
5336 should be relative, and symbolic links pointing from one
5337 top-level directory into another should be absolute. (A
5338 top-level directory is a sub-directory of the root
5342 In addition, symbolic links should be specified as short
5343 as possible, i.e., link targets like `foo/../bar' are
5347 Note that when creating a relative link using
5348 <prgn>ln</prgn> it is not necessary for the target of the
5349 link to exist relative to the working directory you're
5350 running <prgn>ln</prgn> from; nor is it necessary to
5351 change directory to the directory where the link is to be
5352 made. Simply include the string that should appear as the
5353 target of the link (this will be a pathname relative to
5354 the directory in which the link resides) as the first
5355 argument to <prgn>ln</prgn>.</p>
5358 For example, in your <prgn>Makefile</prgn> or
5359 <tt>debian/rules</tt>, do things like:
5361 ln -fs gcc $(prefix)/bin/cc
5362 ln -fs gcc debian/tmp/usr/bin/cc
5363 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5364 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5368 A symbolic link pointing to a compressed file should
5369 always have the same file extension as the referenced
5370 file. (For example, if a file `<tt>foo.gz</tt>' is
5371 referenced by a symbolic link, the filename of the link
5372 has to end with `<tt>.gz</tt>' too, as in
5373 `bar.gz.')</p></sect>
5377 <heading>Device files</heading>
5380 Packages must not include device files in the package file
5384 If a package needs any special device files that are not
5385 included in the base system, it must call
5386 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5387 after asking the user for permission to do so.</p>
5390 Packages must not remove any device files in the
5391 <tt>postrm</tt> or any other script. This is left to the
5392 system administrator.</p>
5395 Debian uses the serial devices
5396 <tt>/dev/ttyS*</tt>. Programs using the old
5397 <tt>/dev/cu*</tt> devices should be changed to use
5398 <tt>/dev/ttyS*</tt>.</p>
5401 <sect id="config files">
5402 <heading>Configuration files</heading>
5404 <heading>Definitions</heading>
5407 <tag>configuration file</tag>
5409 A file that affects the operation of program, or
5410 provides site- or host-specific information, or
5411 otherwise customizes the behavior of program.
5412 Typically, configuration files are intended to be
5413 modified by the system administrator (if needed or
5414 desired) to conform to local policy or provide more
5415 useful site-specific behavior.</p>
5418 <tag><tt>conffile</tt></tag>
5420 A file listed in a package's <tt>conffiles</tt>
5421 file, and is treated specially by <prgn>dpkg</prgn>
5422 (see the <em>Debian Packaging Manual</em>).</p>
5428 The distinction between these two is important; they are
5429 not interchangeable concepts. Almost all
5430 <tt>conffiles</tt> are configuration files, but many
5431 configuration files are not <tt>conffiles</tt>.</p>
5434 Note that a script that embeds configuration information
5435 (such as most of the files in <tt>/etc/init.d</tt> and
5436 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5437 configuration file and should be treated as such.</p>
5441 <heading>Location</heading>
5443 Any configuration files created or used by your package
5444 must reside in <tt>/etc</tt>. If there are several you
5445 should consider creating a subdirectory of <tt>/etc</tt>
5446 named after your package.</p>
5449 If your package creates or uses configuration files
5450 outside of <tt>/etc</tt>, and it is not feasible to modify
5451 the package to use the <tt>/etc</tt>, you should still put
5452 the files in <tt>/etc</tt> and create symbolic links to
5453 those files from the location that the package
5458 <heading>Behavior</heading>
5460 Configuration file handling must conform to the following
5464 <p>local changes must be preserved during a package
5468 <p>configuration files must be preserved when the
5469 package is removed, and only deleted when the
5470 package is purged.</p>
5475 The easy way to achieve this behavior is to make the
5476 configuration file a <tt>conffile</tt>. This is
5477 appropriate only if it is possible to distribute a default
5478 version that will work for most installations, although
5479 some system administrators may choose to modify it. This
5480 implies that the default version will be part of the
5481 package distribution, and must not be modified by the
5482 maintainer scripts during installation (or at any other
5487 In order to ensure that local changes are preserved
5488 correctly, no package may contain or make hard links to
5492 Rationale: There are two problems with hard links.
5493 The first is that some editors break the link while
5494 editing one of the files, so that the two files may
5495 unwittingly become different. The second is that
5496 <prgn>dpkg</prgn> might break the hard link while
5497 upgrading <tt>conffile</tt>s.
5503 The other way to do it is via the maintainer scripts.
5504 In this case, the configuration file must not be listed as
5505 a <tt>conffile</tt> and must not be part of the package
5506 distribution. If the existence of a file is required for
5507 the package to be sensibly configured it is the
5508 responsibility of the package maintainer to write scripts
5509 which correctly create, update, maintain and
5510 remove-on-purge the file. These scripts must be idempotent
5511 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5512 re-run them due to errors during installation or removal),
5513 must cope with all the variety of ways <prgn>dpkg</prgn>
5514 can call maintainer scripts, must not overwrite or
5515 otherwise mangle the user's configuration without asking,
5516 must not ask unnecessary questions (particularly during
5517 upgrades), and otherwise be good citizens.</p>
5520 The scripts are not required to configure every possible option for
5521 the package, but only those necessary to get the package
5522 running on a given system. Ideally the sysadmin should not
5523 have to do any configuration other than that done
5524 (semi-)automatically by the <tt>postinst</tt> script.</p>
5527 A common practice is to create a script called
5528 <tt><var>package</var>-configure</tt> and have the
5529 package's <tt>postinst</tt> call it if and only if the
5530 configuration file does not already exist. In certain
5531 cases it is useful for there to be an example or template
5532 file which the maintainer scripts use. Such files should
5533 be in <tt>/usr/share/<package></tt> or
5534 <tt>/usr/lib/<package></tt> with a symbolic link
5535 from <tt>/usr/share/doc/<package>/examples</tt>
5536 if they are examples, and should be
5537 perfectly ordinary <prgn>dpkg</prgn>-handled files
5538 (<em>not</em> <tt>conffiles</tt>).
5542 These two styles of configuration file handling must
5543 not be mixed, for that way lies madness:
5544 <prgn>dpkg</prgn> will ask about overwriting the file
5545 every time the package is upgraded.</p>
5550 <heading>Sharing configuration files</heading>
5552 Packages which specify the same file as
5553 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5558 The maintainer scripts must not alter the conffile of
5559 <em>any</em> package, including the one the scripts belong
5563 If two or more packages use the same configuration file
5564 and it is reasonable for both to be installed at the same
5565 time, one of these packages must be defined as
5566 <em>owner</em> of the configuration file, i.e., it will be
5567 the package to list that distributes the file and lists it
5568 as a <tt>conffile</tt>. Other packages that use the
5569 configuration file must depend on the owning package if
5570 they require the configuration file to operate. If the
5571 other package will use the configuration file if present,
5572 but is capable of operating without it, no dependency need
5576 If it is desirable for two or more related packages to
5577 share a configuration file <em>and</em> for all of the
5578 related packages to be able to modify that configuration
5579 file, then the following should be done:
5583 have one of the related packages (the "core"
5584 package) manage the configuration file with
5585 maintainer scripts as described in the previous
5589 the core package should also provide a program that
5590 the other packages may use to modify the
5591 configuration file.</p>
5595 the related packages must use the provided program
5596 to make any modifications to the configuration file.
5597 They should either depend on the core package to
5598 guarantee that the configuration modifier program is
5599 available or accept gracefully that they cannot
5600 modify the configuration file if it is not.</p>
5605 Sometimes it's appropriate to create a new package which
5606 provides the basic infrastructure for the other packages
5607 and which manages the shared configuration files. (Check
5608 out the <tt>sgml-base</tt> package as an example.)</p>
5612 <heading>User configuration files ("dotfiles")</heading>
5615 Files in <tt>/etc/skel</tt> will automatically be copied
5616 into new user accounts by <prgn>adduser</prgn>. They
5617 should not be referenced there by any program.</p>
5620 Therefore, if a program needs a dotfile to exist in
5621 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5622 should be installed in <tt>/etc/skel</tt> (and listed in
5623 conffiles, if it is not generated and modified dynamically
5624 by the package's installation scripts).</p>
5627 However, programs that require dotfiles in order to
5628 operate sensibly (dotfiles that they do not create
5629 themselves automatically, that is) are a bad thing, and
5630 programs should be configured by the Debian default
5631 installation as close to normal as possible.</p>
5634 Therefore, if a program in a Debian package needs to be
5635 configured in some way in order to operate sensibly that
5636 configuration should be done in a site-wide global
5637 configuration file elsewhere in <tt>/etc</tt>. Only if the
5638 program doesn't support a site-wide default configuration
5639 and the package maintainer doesn't have time to add it
5640 may a default per-user file be placed in
5641 <tt>/etc/skel</tt>.</p>
5644 <tt>/etc/skel</tt> should be as empty as we can make it.
5645 This is particularly true because there is no easy
5646 mechanism for ensuring that the appropriate dotfiles are
5647 copied into the accounts of existing users when a package
5653 <heading>Log files</heading>
5655 The traditional approach to log files has been to set up ad
5656 hoc log rotation schemes using simple shell scripts and
5657 cron. While this approach is highly customizable, it
5658 requires quite a lot of sysadmin work. Even though the
5659 original Debian system helped a little by automatically
5660 installing a system which can be used as a template, this
5661 was deemed not enough.
5665 A better scheme is to use logrotate, a GPL'd program
5666 developed by Red Hat, which centralizes log management. It
5667 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5668 and a directory where packages can drop logrotation info
5669 (<tt>/etc/logrotate.d</tt>).
5673 Log files should usually be named
5674 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5675 log files, or need a separate directory for permissions
5676 reasons (<tt>/var/log</tt> is writable only by
5677 <tt>root</tt>), you should usually create a directory named
5678 <tt>/var/log/<var>package</var></tt>.</p>
5681 Log files must be rotated occasionally so
5682 that they don't grow indefinitely; the best way to do this
5683 is to drop a script into the directory
5684 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5685 logrotate. Here is a good example for a logrotate config
5686 file (for more information see <manref name="logrotate"
5694 /etc/init.d/foo force-reload
5698 Which rotates all files under `/var/log/foo', saves 12
5699 compressed generations, and sends a HUP signal at the end of
5705 Log files should be removed when the package is
5706 purged (but not when it is only removed), by checking the
5707 argument to the <tt>postrm</tt> script (see the <em>Debian
5708 Packaging Manual</em> for details).</p>
5713 <heading>Permissions and owners</heading>
5716 The rules in this section are guidelines for general use.
5717 If necessary you may deviate from the details below.
5718 However, if you do so you must make sure that what is done
5719 is secure and you should try to be as consistent as possible
5720 with the rest of the system. You should probably also
5721 discuss it on <prgn>debian-devel</prgn> first.</p>
5724 Files should be owned by <tt>root.root</tt>, and made
5725 writable only by the owner and universally readable (and
5726 executable, if appropriate).</p>
5729 Directories should be mode 755 or (for group-writability)
5730 mode 2775. The ownership of the directory should be
5731 consistent with its mode--if a directory is mode 2775, it
5732 should be owned by the group that needs write access to
5736 Setuid and setgid executables should be mode 4755 or 2755
5737 respectively, and owned by the appropriate user or group.
5738 They should not be made unreadable (modes like 4711 or
5739 2711 or even 4111); doing so achieves no extra security,
5740 because anyone can find the binary in the freely available
5741 Debian package--it is merely inconvenient. For the same
5742 reason you should not restrict read or execute permissions
5743 on non-set-id executables.</p>
5746 Some setuid programs need to be restricted to particular
5747 sets of users, using file permissions. In this case they
5748 should be owned by the uid to which they are set-id, and
5749 by the group which should be allowed to execute them.
5750 They should have mode 4754; there is no point in making
5751 them unreadable to those users who must not be allowed to
5755 You must not arrange that the system administrator can only
5756 reconfigure the package to correspond to their local
5757 security policy by changing the permissions on a binary.
5758 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5759 to conffiles and other similar objects) have their
5760 permissions reset to the distributed permissions when the
5761 package is reinstalled. Instead you should consider (for
5762 example) creating a group for people allowed to use the
5763 program(s) and making any setuid executables executable
5764 only by that group.</p>
5767 If you need to create a new user or group for your package
5768 there are two possibilities. Firstly, you may need to
5769 make some files in the binary package be owned by this
5770 user or group, or you may need to compile the user or
5771 group id (rather than just the name) into the binary
5772 (though this latter should be avoided if possible, as in
5773 this case you need a statically allocated id).</p>
5776 If you need a statically allocated id, you must ask for a
5777 user or group id from the base system
5778 maintainer, and must not release the package until you
5779 have been allocated one. Once you have been allocated one
5780 you must make the package depend on a version of the base
5781 system with the id present in <tt>/etc/passwd</tt> or
5782 <tt>/etc/group</tt>, or alternatively arrange for your
5783 package to create the user or group itself with the
5784 correct id (using <tt>adduser</tt>) in its pre- or
5785 post-installation script (the latter is to be preferred if
5786 it is possible).</p>
5789 On the other hand, the program might be able to determine the
5790 uid or gid from the group name at runtime, so that a
5791 dynamic id can be used. In this case you should choose an
5792 appropriate user or group name, discussing this on
5793 <prgn>debian-devel</prgn> and checking with the base
5794 system maintainer that it is unique and that they do not
5795 wish you to use a statically allocated id instead. When
5796 this has been checked you must arrange for your package to
5797 create the user or group if necessary using
5798 <prgn>adduser</prgn> in the pre- or post-installation
5799 script (again, the latter is to be preferred if it is
5803 Note that changing the numeric value of an id associated with a name
5804 is very difficult, and involves searching the file system for all
5805 appropriate files. You need to think carefully whether a static or
5806 dynamic id is required, since changing your mind later will cause
5812 <heading>Customized programs</heading>
5814 <sect id="arch-spec">
5815 <heading>Architecture specification strings</heading>
5818 If a program needs to specify an <em>architecture specification
5819 string</em> in some place, the following format should be used:
5821 <arch>-<os>
5823 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5824 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5825 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5826 operating system.</p>
5828 Note, that we don't want to use `<arch>-debian-linux'
5829 to apply to the rule `architecture-vendor-os' since this
5830 would make our programs incompatible to other Linux
5831 distributions. Also note, that we don't use
5832 `<arch>-unknown-linux', since the `unknown' does not
5833 look very good.</p></sect>
5837 <heading>Daemons</heading>
5840 The configuration files <tt>/etc/services</tt>,
5841 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5842 by the <prgn>netbase</prgn> package and may not be modified
5843 by other packages.</p>
5846 If a package requires a new entry in one of these files, the
5847 maintainer should get in contact with the
5848 <prgn>netbase</prgn> maintainer, who will add the entries
5849 and release a new version of the <prgn>netbase</prgn>
5853 The configuration file <tt>/etc/inetd.conf</tt> must not be
5854 modified by the package's scripts except via the
5855 <prgn>update-inetd</prgn> script or the
5856 <prgn>DebianNet.pm</prgn> Perl module.</p>
5859 If a package wants to install an example entry into
5860 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5861 exactly one hash character (<tt>#</tt>). Such lines are
5862 treated as `commented out by user' by the
5863 <prgn>update-inetd</prgn> script and are not changed or
5864 activated during a package updates.</p></sect>
5868 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5871 Some programs need to create pseudo-ttys. This should be done
5872 using Unix98 ptys if the C library supports it. The resulting
5873 program must not be installed setuid root, unless that
5874 is required for other functionality.
5878 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5879 <tt>/var/log/lastlog</tt> must be installed writeable by
5880 group utmp. Programs who need to modify those files must
5881 be installed setgid utmp.
5886 <heading>Editors and pagers</heading>
5889 Some programs have the ability to launch an editor or pager
5890 program to edit or display a text document. Since there are
5891 lots of different editors and pagers available in the Debian
5892 distribution, the system administrator and each user should
5893 have the possibility to choose his/her preferred editor and
5897 In addition, every program should choose a good default
5898 editor/pager if none is selected by the user or system
5902 Thus, every program that launches an editor or pager must
5903 use the EDITOR or PAGER environment variables to determine
5904 the editor/pager the user wants to get started. If these
5905 variables are not set, the programs <tt>/usr/bin/editor</tt>
5906 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5909 These two files are managed through `alternatives.' That is,
5910 every package providing an editor or pager must call the
5911 <prgn>update-alternatives</prgn> script to register these
5915 If it is very hard to adapt a program to make us of the
5916 EDITOR and PAGER variables, that program may be configured
5917 to use <tt>/usr/bin/sensible-editor</tt> and
5918 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5919 respectively. These are two scripts provided in the Debian
5920 base system that check the EDITOR and PAGER variables and
5921 launch the appropriate program or fall back to
5922 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5926 A program may also use the VISUAL environment variable to
5927 determine the user's choice of editor. If it exists, it
5928 should take precedence over EDITOR. This is in fact what
5929 <tt>/usr/bin/sensible-editor</tt> does.</p>
5932 It is not required for a package to depend on
5933 `editor' and `pager', nor is it required for a package to
5934 provide such virtual packages.
5937 The Debian base system already provides an editor and
5946 <sect id="web-appl">
5947 <heading>Web servers and applications</heading>
5950 This section describes the locations and URLs that should
5951 be used by all web servers and web application in the Debian
5957 <p>Cgi-bin executable files are installed in the
5960 /usr/lib/cgi-bin/<cgi-bin-name>
5962 and should be referred to as
5964 http://localhost/cgi-bin/<cgi-bin-name>
5965 </example></p></item>
5968 <item><p>Access to html documents</p>
5971 Html documents for a package are stored in
5972 <tt>/usr/share/doc/<var>package</var></tt> but should
5973 be accessed via symlinks as
5974 <tt>/usr/doc/<var>package</var></tt><footnote> for
5975 backward compatibility, see <ref id="usrdoc"></footnote>
5976 and can be referred to as
5978 http://localhost/doc/<package>/<filename>
5979 </example></p></item>
5982 <item><p>Web Document Root</p>
5985 Web Applications should try to avoid storing files in
5986 the Web Document Root. Instead they should use the
5987 /usr/share/doc/<package> directory for documents and
5988 register the Web Application via the menu package. If
5989 access to the web-root is unavoidable then use
5993 as the Document Root. This might be just a
5994 symbolic link to the location where the sysadmin has
5995 put the real document root.</p>
5998 </enumlist></p></sect>
6002 <heading>Mail transport, delivery and user agents</heading>
6005 Debian packages which process electronic mail, whether
6006 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6007 must make sure that they are compatible with the
6008 configuration decisions below. Failure to do this may
6009 result in lost mail, broken <tt>From:</tt> lines, and other
6010 serious brain damage!</p>
6013 The mail spool is <tt>/var/spool/mail</tt> and the interface
6014 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6015 per the FHS). The mail spool is part of the base system
6016 and not part of the MTA package.</p>
6019 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6020 programs (like IMAP daemons) must lock the mailbox in an
6021 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6022 be combined with dot locking. To avoid deadlocks, a
6023 program should use <tt>fcntl()</tt> first and dot locking
6024 after this or alternatively implement the two locking
6025 methods in a non blocking way<footnote>
6027 If it is not possible to establish both locks, the
6028 system shouldn't wait for the second lock to be
6029 established, but remove the first lock, wait a (random)
6030 time, and start over locking again.</p>
6031 </footnote>. Using the functions <tt>maillock</tt> and
6032 <tt>mailunlock</tt> provided by the
6033 <tt>liblockfile*</tt><footnote>
6035 <tt>liblockfile</tt> version >>1.01</p>
6036 </footnote> packages is the recommended way to realize this.
6040 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6041 unless the user has chosen otherwise. A MUA may remove a
6042 mailbox (unless it has nonstandard permissions) in which
6043 case the MTA or another MUA must recreate it if needed.
6044 Mailboxes must be writable by group mail.</p>
6047 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6048 be setgid mail to do the locking mentioned above (and
6049 must obviously avoid accessing other users' mailboxes
6050 using this privilege).</p>
6053 <tt>/etc/aliases</tt> is the source file for the system mail
6054 aliases (e.g., postmaster, usenet, etc.)--it is the one
6055 which the sysadmin and <tt>postinst</tt> scripts may edit.
6056 After <tt>/etc/aliases</tt> is edited the program or human
6057 editing it must call <prgn>newaliases</prgn>. All MTA
6058 packages must come with a <prgn>newaliases</prgn> program,
6059 even if it does nothing, but older MTA packages do not do
6060 this so programs should not fail if <prgn>newaliases</prgn>
6061 cannot be found.</p>
6064 The convention of writing <tt>forward to
6065 <var>address</var></tt> in the mailbox itself is not
6066 supported. Use a <tt>.forward</tt> file instead.</p>
6069 The <prgn>rmail</prgn> program used by UUCP
6070 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6071 Likewise, <prgn>rsmtp</prgn>, for receiving
6072 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6076 If you need to know what name to use (for example) on
6077 outgoing news and mail messages which are generated locally,
6078 you should use the file <tt>/etc/mailname</tt>. It will
6079 contain the portion after the username and <tt>@</tt> (at)
6080 sign for email addresses of users on the machine (followed
6084 A package should check for the existence of this file. If
6085 it exists it should use it without comment. (An MTA's
6086 prompting configuration script may wish to prompt the user
6087 even if it finds this file exists.) If it does not exist it
6088 should prompt the user for the value and store it in
6089 <tt>/etc/mailname</tt> as well as using it in the package's
6090 configuration. The prompt should make it clear that the
6091 name will not just be used by that package. For example, in
6092 this situation the INN package says:
6094 Please enter the `mail name' of your system. This is the
6095 hostname portion of the address to be shown on outgoing
6096 news and mail messages. The default is
6097 <var>syshostname</var>, your system's host name. Mail
6098 name [`<var>syshostname</var>']:
6100 where <var>syshostname</var> is the output of <tt>hostname
6101 --fqdn</tt>.</p></sect>
6105 <heading>News system configuration</heading>
6108 All the configuration files related to the NNTP (news)
6109 servers and clients should be located under
6110 <tt>/etc/news</tt>.</p>
6113 There are some configuration issues that apply to a number
6114 of news clients and server packages on the machine. These
6118 <tag>/etc/news/organization</tag>
6119 <item><p>A string which should appear as the
6120 organization header for all messages posted
6121 by NNTP clients on the machine</p></item>
6123 <tag>/etc/news/server</tag>
6124 <item><p>Contains the FQDN of the upstream NNTP
6125 server, or localhost if the local machine is
6126 an NNTP server.</p></item>
6129 Other global files may be added as required for cross-package news
6130 configuration.</p></sect>
6134 <heading>Programs for the X Window System</heading>
6137 <em>Programs that may be configured with support for the X Window
6138 System</em> must be configured to do so and must declare any
6139 package dependencies necessary to satisfy their runtime
6140 requirements when using the X Window System, unless the package
6141 in question is of standard or higher priority, in which case
6142 X-specific binaries may be split into a separate package, or
6143 alternative versions of the package with X support may be
6149 <em>Packages which provide an X server</em> that, directly or
6150 indirectly, communicates with real input and display hardware
6151 should declare in their control data that they provide the
6152 virtual package <tt>xserver</tt>.
6155 This implements current practice, and provides an actual
6156 policy for usage of the "xserver" virtual package which
6157 appears in the virtual packages list. In a nutshell, X
6158 servers that interface directly with the display and input
6159 hardware or via another subsystem (e.g., GGI) should provide
6160 xserver. Things like Xvfb, Xnest, and Xprt should not.
6166 <em>Packages that provide a terminal emulator</em> for the X
6167 Window System which support a terminal type with a terminfo
6168 description provided in the <tt>ncurses-base</tt> package
6169 should declare in their control data that they provide the
6170 virtual package <tt>x-terminal-emulator</tt>. They should
6171 also register themselves as an alternative for
6172 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6177 <em>Packages that provide window managers</em> should declare in
6178 their control data that they provide the virtual package
6179 <tt>x-window-manager</tt>. They should also register themselves as an
6180 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6181 calculated as follows:
6183 <item>Start with a priority of 20.</item>
6184 <item>If the window manager supports the Debian menu system,
6185 add 20 points if this support is available in the
6186 package's default configuration (i.e., no
6187 configuration files belonging to the system or user
6188 have to be edited to activate the feature); if
6189 configuration files must be modified, add only 10
6191 <item>If the window manager permits the X session to be
6192 restarted using a <em>different</em> window manager
6193 (without killing the X server) in its default
6194 configuration, add 10 points; otherwise add
6200 <em>Packages that provide fonts for the X Window System</em>
6201 must do a number of things to ensure that they are both
6202 available without modification of the X or font server
6203 configuration, and that they do not corrupt files used by
6204 other font packages to register information about themselves.
6207 Fonts of any type supported by the X Window System
6208 should be be in a separate binary package from any
6209 executables, libraries, or documentation (except that
6210 specific to the fonts shipped); if a program or
6211 library is <em>unusable</em> without one or more
6212 specific fonts, the package containing the program or
6213 library should declare a dependency on the package(s)
6214 containing the font(s) it requires.
6217 BDF fonts should be converted to PCF fonts with the
6218 <tt>bdftopcf</tt> utility (available in the
6219 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6220 placed in a directory that corresponds to their
6224 100 dpi fonts should be placed in
6225 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6228 75 dpi fonts should be placed in
6229 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6232 Character-cell fonts, cursor fonts, and other
6233 low-resolution fonts should be placed in
6234 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6239 Speedo fonts should be placed in
6240 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6243 Type 1 fonts should be placed in
6244 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6245 metric files are available, they may be placed here as
6249 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6250 other than those listed above should be neither created nor
6251 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6252 excepted for historical reasons, but installation of files into
6253 these directories remains discouraged.)
6256 Font packages may, instead of placing files directly in
6257 the X font directories listed above, provide symbolic links in
6258 the font directory which point to the files' actual location
6259 in the filesystem. Such a location should comply with the
6263 Font packages should not contain both 75dpi and 100dpi
6264 versions of a font. If both are available, they should be
6265 provided in separate binary packages with "-75dpi" or "-100dpi"
6266 appended to the names of the packages containing the
6267 corresponding fonts.
6270 Fonts destined for the <tt>misc</tt> subdirectory should
6271 not be included in the same package as 75dpi or 100dpi fonts;
6272 instead, they should be provided in a separate package with
6273 "-misc" appended to its name.
6276 Font packages <em>must not</em> provide the files
6277 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6278 <tt>fonts.scale</tt> in a font directory.
6281 <tt>fonts.dir</tt> files must not be provided at
6285 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6286 files, if needed, should be provided in the
6288 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6289 where <em>fontdir</em> is the name of the
6291 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6292 package's corresponding fonts are stored (e.g.,
6293 <tt>75dpi</tt> or <tt>misc</tt>),
6294 <em>package</em> is the name of the package that
6295 provides these fonts, and <em>extension</em> is
6296 either <tt>scale</tt> or <tt>alias</tt>,
6297 whichever corresponds to the file
6303 Font packages must declare a dependency on
6304 <tt>xutils</tt> and, in the package
6305 post-installation and post-removal scripts, invoke the
6306 <tt>mkfontdir</tt> command on each directory into
6307 which they installed fonts.
6310 Font packages that provide one or more
6311 <tt>fonts.scale</tt> files as described above must declare a
6312 versioned dependency on <tt>xutils (>=
6313 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6314 directory into which they installed fonts
6315 <em>before</em> invoking <tt>mkfontdir</tt> on that
6316 directory. This invocation must occur in both the
6317 post-installation and post-removal scripts.
6320 Font packages that provide one or more
6321 <tt>fonts.alias</tt> files as described above must
6322 declare a versioned dependency on <tt>xutils
6323 (>= 4.0.2)</tt> and, in the package
6324 post-installation and post-removal scripts, invoke
6325 <tt>update-fonts-alias</tt> on each directory into
6326 which they installed fonts.
6329 Font packages must not provide alias names for the
6330 fonts they include which collide with alias names already in
6331 use by fonts already packaged.
6334 Font packages must not provide fonts with the same XLFD
6335 registry name as another font already packaged.
6341 <em>Application defaults</em> files must be installed in the
6342 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6343 localized subdirectory of <tt>/etc/X11/</tt> as described in
6344 the <em>X Toolkit Intrinsics - C Language Interface</em>
6345 manual is also permitted). They must be registered as
6346 <em>conffile</em>s or handled as configuration files. For
6347 programs that are not linked against the X Toolkit (Xt)
6348 library, customization of programs' X resources may also be
6349 supported with the provision of a file with the same name as
6350 that of the package placed in the
6351 <tt>/etc/X11/Xresources/</tt> directory, which must
6352 registered as a <em>conffile</em> or handled as a
6353 configuration file. <em>Important:</em> packages that
6354 install files into the <tt>/etc/X11/Xresources/</tt>
6355 directory <em>must</em> declare a conflict with <tt>xbase
6356 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6357 possible for the installing package to destroy a
6358 previously-existing <tt>/etc/X11/Xresources</tt> file which
6359 had been customized by the system administrator.
6363 <em>Packages using the X Window System should abide by the FHS
6364 standard whenever possible</em>; they should install binaries,
6365 libraries, manual pages, and other files in FHS-mandated
6366 locations wherever possible. This means that files must
6367 not be installed into <tt>/usr/X11R6/bin/</tt>,
6368 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6369 this is necessary for the package to operate properly.
6370 Configuration files for window managers and display managers
6371 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6372 corresponding to the package name due to these programs'
6373 tight integration with the mechanisms of the X Window
6374 System. Application-level programs should use the
6375 <tt>/etc/</tt> directory unless otherwise mandated by
6376 policy. The installation of files into subdirectories of
6377 <tt>/usr/X11R6/include/X11/</tt> and
6378 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6379 package maintainers should determine if subdirectories of
6380 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6381 instead (symlinks from the X11R6 directories to
6382 FHS-compliant locations is encouraged if the program is not
6383 easily configured to look elsewhere for its files).
6384 Packages must not provide -- or install files into -- the
6385 directories <tt>/usr/bin/X11/</tt>,
6386 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6387 Files within a package should, however, make reference to
6388 these directories, rather than their X11R6-named
6389 counterparts <tt>/usr/X11R6/bin/</tt>,
6390 <tt>/usr/X11R6/include/X11/</tt>, and
6391 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6392 referred to have not been moved to FHS-compliant locations.
6396 <em>Programs that require the non-DFSG-compliant OSF/Motif
6397 library</em> should be compiled against and tested with
6398 LessTif (a free re-implementation of Motif) instead. If the
6399 maintainer judges that the program or programs do not work
6400 sufficiently well with LessTif to be distributed and
6401 supported, but do so when compiled against Motif, then two
6402 versions of the package should be created; one linked
6403 statically against Motif and with <tt>-smotif</tt> appended
6404 to the package name, and one linked dynamically against
6405 Motif and with <tt>-dmotif</tt> appended to the package
6406 name. Both Motif-linked versions are dependent upon
6407 non-DFSG-compliant software and thus cannot be uploaded to
6408 the main distribution; if the software is itself
6409 DFSG-compliant it may be uploaded to the contrib
6410 distribution. While known existing versions of OSF/Motif
6411 permit unlimited redistribution of binaries linked against
6412 the library (whether statically or dynamically), it is the
6413 package maintainer's responsibility to determine whether
6414 this is permitted by the license of the copy of OSF/Motif in
6415 his or her possession.
6421 <heading>Emacs lisp programs</heading>
6424 Please refer to the `Debian Emacs Policy' (documented in
6425 <tt>debian-emacs-policy.gz</tt> of the
6426 <prgn>emacsen-common</prgn> package) for details of how to
6427 package emacs lisp programs.</p></sect>
6431 <heading>Games</heading>
6434 The permissions on /var/games are 755
6435 <tt>root.root</tt>.</p>
6438 Each game decides on its own security policy.</p>
6441 Games which require protected, privileged access to
6442 high-score files, savegames, etc., may be made
6443 set-<em>group</em>-id (mode 2755) and owned by
6444 <tt>root.games</tt>, and use files and directories with
6445 appropriate permissions (770 <tt>root.games</tt>, for
6446 example). They must not be made
6447 set-<em>user</em>-id, as this causes security problems. (If
6448 an attacker can subvert any set-user-id game they can
6449 overwrite the executable of any other, causing other players
6450 of these games to run a Trojan horse program. With a
6451 set-group-id game the attacker only gets access to less
6452 important game data, and if they can get at the other
6453 players' accounts at all it will take considerably more
6457 Some packages, for example some fortune cookie programs, are
6458 configured by the upstream authors to install with their
6459 data files or other static information made unreadable so
6460 that they can only be accessed through set-id programs
6461 provided. You should not do this in a Debian package: anyone can
6462 download the <tt>.deb</tt> file and read the data from it,
6463 so there is no point making the files unreadable. Not
6464 making the files unreadable also means that you don't have
6465 to make so many programs set-id, which reduces the risk of a
6469 As described in the FHS, binaries of games should be
6470 installed in the directory <tt>/usr/games</tt>. This also
6471 applies to games that use the X Window System. Manual pages
6472 for games (X and non-X games) should be installed in
6473 <tt>/usr/share/man/man6</tt>.</p>
6477 <chapt><heading>Documentation</heading>
6481 <heading>Manual pages</heading>
6484 You should install manual pages in <prgn>nroff</prgn> source
6485 form, in appropriate places under <tt>/usr/share/man</tt>. You
6486 should only use sections 1 to 9 (see the FHS for more
6487 details). You must not install a preformatted `cat
6491 Each program, utility, and function should have an
6492 associated manpage included in the same package. It is
6493 suggested that all configuration files also have a manual
6494 page included as well.
6498 If no manual page is available for a particular program,
6499 utility, function or configuration file and this is reported as a bug on
6500 debian-bugs, a symbolic link from the requested manual page
6501 to the <manref name="undocumented" section="7"> manual page
6502 may be provided. This symbolic link can be created from
6503 <tt>debian/rules</tt> like this:
6505 ln -s ../man7/undocumented.7.gz \
6506 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6508 This manpage claims that the lack of a manpage has been
6509 reported as a bug, so you may only do this if it really has
6510 (you can report it yourself, if you like). Do not close the
6511 bug report until a proper manpage is available.</p>
6514 You may forward a complaint about a missing manpage to the
6515 upstream authors, and mark the bug as forwarded in the
6516 Debian bug tracking system. Even though the GNU Project do
6517 not in general consider the lack of a manpage to be a bug,
6518 we do--if they tell you that they don't consider it a bug
6519 you should leave the bug in our bug tracking system open
6523 Manual pages should be installed compressed using <tt>gzip
6527 If one manpage needs to be accessible via several names it
6528 is better to use a symbolic link than the <tt>.so</tt>
6529 feature, but there is no need to fiddle with the relevant
6530 parts of the upstream source to change from <tt>.so</tt> to
6531 symlinks--don't do it unless it's easy. You should not create hard
6532 links in the manual page directories, nor put
6533 absolute filenames in <tt>.so</tt> directives. The filename
6534 in a <tt>.so</tt> in a manpage should be relative to the
6535 base of the manpage tree (usually
6536 <tt>/usr/share/man</tt>).</p></sect>
6540 <heading>Info documents</heading>
6543 Info documents should be installed in <tt>/usr/share/info</tt>.
6544 They should be compressed with <tt>gzip -9</tt>.</p>
6547 Your package should call <prgn>install-info</prgn> to update the Info
6549 file, in its post-installation script:
6551 install-info --quiet --section Development Development \
6552 /usr/share/info/foobar.info
6556 It is a good idea to specify a section for the location of
6557 your program; this is done with the <tt>--section</tt>
6558 switch. To determine which section to use, you should look
6559 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6560 relevant (or create a new section if none of the current
6561 sections are relevant). Note that the <tt>--section</tt>
6562 flag takes two arguments; the first is a regular expression
6563 to match (case-insensitively) against an existing section,
6564 the second is used when creating a new one.</p>
6567 You should remove the entries in the pre-removal script:
6569 install-info --quiet --remove /usr/share/info/foobar.info
6573 If <prgn>install-info</prgn> cannot find a description entry
6574 in the Info file you must supply one. See <manref
6575 name="install-info" section="8"> for details.</p>
6579 <heading>Additional documentation</heading>
6582 Any additional documentation that comes with the package may
6583 be installed at the discretion of the package maintainer.
6584 Text documentation should be installed in a directory
6585 <tt>/usr/share/doc/<var>package</var></tt>, where
6586 <var>package</var> is the name of the package, and
6587 compressed with <tt>gzip -9</tt> unless it is small.</p>
6590 If a package comes with large amounts of documentation which
6591 many users of the package will not require you should create
6592 a separate binary package to contain it, so that it does not
6593 take up disk space on the machines of users who do not need
6594 or want it installed.</p>
6597 It is often a good idea to put text information files
6598 (<tt>README</tt>s, changelogs, and so forth) that come with
6599 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6600 in the binary package. However, you don't need to install
6601 the instructions for building and installing the package, of
6605 Files in <tt>/usr/share/doc</tt> should not be referenced by
6606 any program, and the system administrator should be able to
6607 delete them without causing any programs to break. Any files
6608 that are referenced by programs but are also useful as
6609 standalone documentation should be installed under
6610 <tt>/usr/share/<package>/</tt> and symlinked in
6611 <tt>/usr/share/doc/<package>/</tt>.
6617 <heading>Accessing the documentation</heading>
6620 Former Debian releases placed all additional documentation
6621 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6623 <tt>/usr/share/doc/<var>package</var></tt>, each package
6624 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6625 that points to the new location of its documentation in
6626 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6627 symlinks will be removed in the future, but they have to be
6628 there for compatibility reasons until all packages have
6629 moved and the policy is changed accordingly.</footnote>.
6630 The symlink must be created when the package is installed;
6631 it cannot be contained in the package itself due to problems
6632 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6633 this is to put the following in the package's
6634 <prgn>postinst</prgn>:
6636 if [ "$1" = "configure" ]; then
6637 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6638 -a -d /usr/share/doc/#PACKAGE# ]; then
6639 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6643 And the following in the package's <prgn>prerm</prgn>:
6645 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6646 -a -L /usr/doc/#PACKAGE# ]; then
6647 rm -f /usr/doc/#PACKAGE#
6654 <heading>Preferred documentation formats</heading>
6657 The unification of Debian documentation is being carried out
6661 If your package comes with extensive documentation in a
6662 mark up format that can be converted to various other formats
6663 you should if possible ship HTML versions in a binary
6664 package, in the directory
6665 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6668 <p>The rationale: The important thing here is that HTML
6669 docs should be available in <em>some</em> package, not
6670 necessarily in the main binary package, though. </p>
6675 Other formats such as PostScript may be provided at your
6679 <sect id="copyrightfile">
6680 <heading>Copyright information</heading>
6683 Every package must be accompanied by a verbatim copy of its
6684 copyright and distribution license in the file
6685 /usr/share/doc/<package-name>/copyright. This file must
6686 neither be compressed nor be a symbolic link.</p>
6689 In addition, the copyright file must say where the upstream
6690 sources (if any) were obtained, and should explain briefly what
6691 modifications were made in the Debian version of the package
6692 compared to the upstream one. It should name the original
6693 authors of the package and the Debian maintainer(s) who were
6694 involved with its creation.</p>
6697 A copy of the file which will be installed in
6698 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6699 in <tt>debian/copyright</tt>.</p>
6703 /usr/share/doc/<package-name> may be a symbolic link to a
6704 directory in /usr/share/doc only if two packages both come from
6705 the same source and the first package has a "Depends"
6706 relationship on the second. These rules are important
6707 because copyrights must be extractable by mechanical
6711 Packages distributed under the UCB BSD license, the Artistic
6712 license, the GNU GPL, and the GNU LGPL should refer to the
6713 files /usr/share/common-licenses/BSD,
6714 /usr/share/common-licenses/Artistic,
6715 /usr/share/common-licenses/GPL, and
6716 /usr/share/common-licenses/LGPL.
6719 Why "licenses" and not "copyright"? Because
6720 <tt>/usr/doc/copyright</tt> used to contain all the
6721 copyright files, plus the four common licenses GPL,
6722 LGPL, Artistic and BSD. Now individual copyright files
6723 for packages are no longer in a common directory. Once
6724 <tt>/usr/doc/copyright</tt> is almost empty it makes
6725 sense to rename "copyright" to "licenses"
6728 Why "common-licenses" and not "licenses"? Because if I
6729 put just "licenses" I'm sure I will receive a bug report
6730 saying "license foo is not included in the licenses
6731 directory. They are not all the licenses, just a few
6732 common ones. I could use /usr/share/doc/common-licenses
6733 but I think this is too long, and, after all, the GPL
6734 does not "document" anything, it is merely a license.
6740 You should not use the copyright file as a general <tt>README</tt>
6741 file. If your package has such a file it should be
6742 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6743 <tt>README.Debian</tt> or some other appropriate place.</p>
6747 <heading>Examples</heading>
6750 Any examples (configurations, source files, whatever),
6751 should be installed in a directory
6752 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6753 files should not be referenced by any program--they're there
6754 for the benefit of the system administrator and users, as
6755 documentation only. Architecture-specific example files
6756 should be installed in a directory
6757 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6758 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6759 to files in it. Or the latter directory may be a symlink to
6763 <sect id="instchangelog">
6764 <heading>Changelog files</heading>
6767 Packages that are not Debian-native must contain a copy of
6768 <tt>debian/changelog</tt> file from the Debian source tree
6769 in <tt>/usr/share/doc/<var>package</var></tt> as
6770 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6771 available, it should be accessible as
6772 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6773 plain text. If the upstream changelog is distributed in
6774 HTML, it should be made available in that form as
6775 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6776 and the <tt>changelog.gz</tt> should be generated using, eg,
6777 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6778 do not already conform to this naming convention, then this
6779 may be achieved either by renaming the files, or adding a
6780 symbolic link, at the maintainer's discretion.
6783 Rationale: People should not have to look into two
6784 places for upstream changelogs merely because they are
6792 All these files should be installed compressed using <tt>gzip -9</tt>,
6793 as they will become large with time even if they start out
6798 If the package has only one changelog which is used both as
6799 the Debian changelog and the upstream one because there is
6800 no separate upstream maintainer then that changelog should
6801 usually be installed as
6802 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6803 there is a separate upstream maintainer, but no upstream
6804 changelog, then the Debian changelog should still be called
6805 <tt>changelog.Debian.gz</tt>.</p>