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8 Debian GNU/Linux Policy Manual.
9 Copyright (C)1996,1997,1998 Ian Jackson and Christian Schwarz;
10 released under the terms of the GNU
11 General Public License, version 2 or (at your option) any later.
12 Initial version 1996, Ian Jackson, ijackson@gnu.ai.mit.edu
13 Revised November 27, 1996, David A. Morris, bweaver@debian.org
14 New sections March 15, 1997, Christian Schwarz, schwarz@debian.org
15 Reworked/Restructured April-July 1997, Christian Schwarz, schwarz@debian.org
16 Maintainer since 1997, Christian Schwarz, schwarz@debian.org
17 Christoph Lameter contributed the "Web Standard"
18 The debian-policy mailing list has taken responsibility for the
19 contents of this document since September 1998, with the package
20 maintainers responsible for packaging administrivia only.
25 <title>Debian Policy Manual</title>
27 <name>Ian Jackson </name>
28 <email>ijackson@gnu.ai.mit.edu</email>
31 <name>Christian Schwarz</name>
32 <email>schwarz@debian.org</email>
35 <name>revised: David A. Morris</name>
36 <email>bweaver@debian.org</email>
39 <name>The Debian Policy mailing List</name>
40 <email>debian-policy@lists.debian.org</email>
42 <version>version &version;, &date;</version>
45 This manual describes the policy requirements for the Debian
46 GNU/Linux distribution. This includes the structure and
47 contents of the Debian archive and several design issues of the
48 operating system, as well as technical requirements that each
49 package must satisfy to be included in the distribution. The
50 policy package itself is maintained by a group of maintainers
51 that have no editorial powers. At the moment, the list of
55 <p>Julian Gilbey <email>jdg@debian.org</email></p>
58 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
66 Copyright ©1996,1997,1998 Ian Jackson
67 and Christian Schwarz.
70 This manual is free software; you may redistribute it and/or
71 modify it under the terms of the GNU General Public License
72 as published by the Free Software Foundation; either version
73 2, or (at your option) any later version.
77 This is distributed in the hope that it will be useful, but
78 <em>without any warranty</em>; without even the implied
79 warranty of merchantability or fitness for a particular
80 purpose. See the GNU General Public License for more
85 A copy of the GNU General Public License is available as
86 <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
87 distribution or on the World Wide Web at
88 <url id="http://www.gnu.org/copyleft/gpl.html"
89 name="The GNU General Public Licence">. You can also
90 obtain it by writing to the Free Software Foundation, Inc.,
91 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
99 <heading>About this manual</heading>
101 <heading>Scope</heading>
103 This manual describes the policy requirements for the Debian
104 GNU/Linux distribution. This includes the structure and
105 contents of the Debian archive and several design issues of the
106 operating system, as well as technical requirements that
107 each package must satisfy to be included in the
113 This manual also describes Debian policy as it relates to
114 creating Debian packages. It is not a tutorial on how to build
115 packages, nor is it exhaustive where it comes to describing
116 the behavior of the packaging system. Instead, this manual
117 attempts to define the interface to the package management
118 system that the developers have to be conversant with.
121 Informally, the criteria used for inclusion is that the
122 material meet one of the following requirements:
123 <taglist compact="compact">
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 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 to 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.
240 <heading>The Debian Archive</heading>
242 The Debian GNU/Linux system is maintained and distributed as a
243 collection of <em>packages</em>. Since there are so many of
244 them (currently well over 6000), they are split into
245 <em>sections</em> and given <em>priorities</em> to simplify
246 the handling of them.
249 The effort of the Debian project is to build a free operating
250 system, but not every package we want to make accessible is
251 <em>free</em> in our sense (see the Debian Free Software
252 Guidelines, below), or may be imported/exported without
253 restrictions. Thus, the archive is split into the sections
254 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
255 <em>non-US/main</em>, <em>non-US/non-free</em>, and
256 <em>non-US/contrib</em>. The sections are explained in detail
261 The <em>main</em> and the <em>non-US/main</em> sections
262 together form the <em>Debian GNU/Linux distribution</em>.
266 Packages in the other sections are not considered to be part
267 of the Debian distribution, although we support their use and
268 provide infrastructure for them (such as our bug-tracking
269 system and mailing lists). This Debian Policy Manual applies
270 to these packages as well.</p>
272 <sect id="pkgcopyright">
273 <heading>Package copyright and sections</heading>
275 The aims of this section are:
277 <list compact="compact">
279 <p>to allow us to make as much software available as we
283 <p>to allow us to encourage everyone to write free
287 <p>to allow us to make it easy for people to produce
288 CD-ROMs of our system without violating any licenses,
289 import/export restrictions, or any other laws.</p>
294 <heading>The Debian Free Software Guidelines</heading>
296 The Debian Free Software Guidelines (DFSG) form our
297 definition of `free software'. These are:
299 <tag>Free Redistribution
303 The license of a Debian component may not restrict any
304 party from selling or giving away the software as a
305 component of an aggregate software distribution
306 containing programs from several different
307 sources. The license may not require a royalty or
308 other fee for such sale.
315 The program must include source code, and must allow
316 distribution in source code as well as compiled form.
323 The license must allow modifications and derived
324 works, and must allow them to be distributed under the
325 same terms as the license of the original software.
328 <tag>Integrity of The Author's Source Code
332 The license may restrict source-code from being
333 distributed in modified form <em>only</em> if the
334 license allows the distribution of ``patch files''
335 with the source code for the purpose of modifying the
336 program at build time. The license must explicitly
337 permit distribution of software built from modified
338 source code. The license may require derived works to
339 carry a different name or version number from the
340 original software. (This is a compromise. The Debian
341 Project encourages all authors to not restrict any
342 files, source or binary, from being modified.)
345 <tag>No Discrimination Against Persons or Groups
349 The license must not discriminate against any person
353 <tag>No Discrimination Against Fields of Endeavor
357 The license must not restrict anyone from making use
358 of the program in a specific field of endeavor. For
359 example, it may not restrict the program from being
360 used in a business, or from being used for genetic
364 <tag>Distribution of License
368 The rights attached to the program must apply to all
369 to whom the program is redistributed without the need
370 for execution of an additional license by those
374 <tag>License Must Not Be Specific to Debian
378 The rights attached to the program must not depend on
379 the program's being part of a Debian system. If the
380 program is extracted from Debian and used or
381 distributed without Debian but otherwise within the
382 terms of the program's license, all parties to whom
383 the program is redistributed must have the same
384 rights as those that are granted in conjunction with
388 <tag>License Must Not Contaminate Other Software
392 The license must not place restrictions on other
393 software that is distributed along with the licensed
394 software. For example, the license must not insist
395 that all other programs distributed on the same medium
396 must be free software.
399 <tag>Example Licenses
403 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
404 examples of licenses that we consider <em>free</em>.
411 <heading>The main section</heading>
413 Every package in <em>main</em> and <em>non-US/main</em>
414 must comply with the DFSG (Debian Free Software
418 In addition, the packages in <em>main</em>
419 <list compact="compact">
422 must not require a package outside of <em>main</em>
423 for compilation or execution (thus, the package must
424 not declare a "Depends", "Recommends", or
425 "Build-Depends" relationship on a non-<em>main</em>
431 must not be so buggy that we refuse to support them,
437 must meet all policy requirements presented in this
444 Similarly, the packages in <em>non-US/main</em>
445 <list compact="compact">
448 must not require a package outside of <em>main</em>
449 or <em>non-US/main</em> for compilation or
455 must not be so buggy that we refuse to support them,
460 must meet all policy requirements presented in this
468 <heading>The contrib section</heading>
470 Every package in <em>contrib</em> and
471 <em>non-US/contrib</em> must comply with the DFSG.
475 In addition, the packages in <em>contrib</em> and
476 <em>non-US/contrib</em>
477 <list compact="compact">
480 must not be so buggy that we refuse to support them,
486 must meet all policy requirements presented in this
494 Furthermore, packages in <em>contrib</em> must not require
495 a package in a <em>non-US</em> section for compilation or
500 Examples of packages which would be included in
501 <em>contrib</em> or <em>non-US/contrib</em> are:
502 <list compact="compact">
505 free packages which require <em>contrib</em>,
506 <em>non-free</em> packages or packages which are not
507 in our archive at all for compilation or execution,
513 wrapper packages or other sorts of free accessories for
521 <heading>The non-free section</heading>
523 Packages must be placed in <em>non-free</em> or
524 <em>non-US/non-free</em> if they are not compliant with
525 the DFSG or are encumbered by patents or other legal
526 issues that make their distribution problematic.
529 In addition, the packages in <em>non-free</em> and
530 <em>non-US/non-free</em>
531 <list compact="compact">
534 must not be so buggy that we refuse to support them,
540 must meet all policy requirements presented in this
541 manual that it is possible for them to meet.
544 It is possible that there are policy
545 requirements which the package is unable to
546 meet, for example, if the source is
547 unavailable. These situations will need to be
548 handled on a case-by-case basis.
558 <heading>The non-US sections</heading>
560 Some programs with cryptographic program code need to be
561 stored on the <em>non-US</em> server because of United
562 States export restrictions. Such programs must be
563 distributed in the appropriate <em>non-US</em> section,
564 either <em>non-US/main</em>, <em>non-US/contrib</em> or
565 <em>non-US/non-free</em>.
568 This applies only to packages which contain cryptographic
569 code. A package containing a program with an interface to
570 a cryptographic program or a program that's dynamically
571 linked against a cryptographic library should not be
572 distributed via the <em>non-US</em> server if it is
573 capable of running without the cryptographic library or
578 <heading>Further copyright considerations</heading>
580 Every package must be accompanied by a verbatim copy of
581 its copyright and distribution license in the file
582 <tt>/usr/share/doc/<em><package></em>/copyright</tt>
583 (see <ref id="copyrightfile"> for further details).
586 We reserve the right to restrict files from being included
587 anywhere in our archives if
588 <list compact="compact">
591 their use or distribution would break a law,
596 there is an ethical conflict in their distribution or
602 we would have to sign a license for them, or
607 their distribution would conflict with other project
615 Programs whose authors encourage the user to make
616 donations are fine for the main distribution, provided
617 that the authors do not claim that not donating is
618 immoral, unethical, illegal or something similar; in such
619 a case they must go in <em>non-free</em>.</p>
622 Packages whose copyright permission notices (or patent
623 problems) do not even allow redistribution of binaries
624 only, and where no special permission has been obtained,
625 must not be placed on the Debian FTP site and its mirrors
629 Note that under international copyright law (this applies
630 in the United States, too), <em>no</em> distribution or
631 modification of a work is allowed without an explicit
632 notice saying so. Therefore a program without a copyright
633 notice <em>is</em> copyrighted and you may not do anything
634 to it without risking being sued! Likewise if a program
635 has a copyright notice but no statement saying what is
636 permitted then nothing is permitted.</p>
639 Many authors are unaware of the problems that restrictive
640 copyrights (or lack of copyright notices) can cause for
641 the users of their supposedly-free software. It is often
642 worthwhile contacting such authors diplomatically to ask
643 them to modify their license terms. However, this can be a
644 politically difficult thing to do and you should ask for
645 advice on the <tt>debian-legal</tt> mailing list first, as
650 When in doubt about a copyright, send mail to
651 <email>debian-legal@lists.debian.org</email>. Be prepared
652 to provide us with the copyright statement. Software
653 covered by the GPL, public domain software and BSD-like
654 copyrights are safe; be wary of the phrases `commercial
655 use prohibited' and `distribution restricted'.
659 <heading>Subsections</heading>
662 The packages in the sections <em>main</em>,
663 <em>contrib</em> and <em>non-free</em> are grouped further
664 into <em>subsections</em> to simplify handling.
668 The section and subsection for each package should be
669 specified in the package's <tt>Section</tt> control
670 record. However, the maintainer of the Debian archive
671 may override this selection to ensure the consistency of
672 the Debian distribution. The <tt>Section</tt> field
673 should be of the form:
674 <list compact="compact">
677 <em>subsection</em> if the package is in the
678 <em>main</em> section,
683 <em>section/subsection</em> if the package is in
684 the <em>contrib</em> or <em>non-free</em> section,
690 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
691 <tt>non-US/non-free</tt> if the package is in
692 <em>non-US/main</em>, <em>non-US/contrib</em> or
693 <em>non-US/non-free</em> respectively.
700 The Debian archive maintainers provide the authoritative
701 list of subsections. At present, they are:
702 <em>admin</em>, <em>base</em>, <em>comm</em>,
703 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
704 <em>editors</em>, <em>electronics</em>, <em>games</em>,
705 <em>graphics</em>, <em>hamradio</em>,
706 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
707 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
708 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
709 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
710 <em>sound</em>, <em>tex</em>, <em>text</em>,
711 <em>utils</em>, <em>web</em>, <em>x11</em>.
715 <heading>Priorities</heading>
718 Each package should have a <em>priority</em> value, which is
719 included in the package's <em>control record</em>. This
720 information is used by the Debian package management tools
721 to separate high-priority packages from less-important
725 The following <em>priority levels</em> are recognised by the
726 Debian package management tools.
728 <tag><tt>required</tt></tag>
731 Packages which are necessary for the proper
732 functioning of the system. You must not remove these
733 packages or your system may become totally broken and
734 you may not even be able to use <prgn>dpkg</prgn> to
735 put things back. Systems with only the
736 <tt>required</tt> packages are probably unusable, but
737 they do have enough functionality to allow the
738 sysadmin to boot and install more software.</p>
740 <tag><tt>important</tt></tag>
743 Important programs, including those which one would
744 expect to find on any Unix-like system. If the
745 expectation is that an experienced Unix person who
746 found it missing would say `What on earth is going on,
747 where is <prgn>foo</prgn>?', it must be an
748 <tt>important</tt> package.
751 This is an important criterion because we are
752 trying to produce, amongst other things, a free
756 Other packages without which the system will not run
757 well or be usable must also have priority
758 <tt>important</tt>. This does
759 <em>not</em> include Emacs, the X Window System, TeX
760 or any other large applications. The
761 <tt>important</tt> packages are just a bare minimum of
762 commonly-expected and necessary tools.</p>
764 <tag><tt>standard</tt></tag>
767 These packages provide a reasonably small but not too
768 limited character-mode system. This is what will be
769 installed by default if the user doesn't select anything
770 else. It doesn't include many large applications, but
771 it does include Emacs (this is more of a piece of
772 infrastructure than an application) and a reasonable
773 subset of TeX and LaTeX.</p>
775 <tag><tt>optional</tt></tag>
778 (In a sense everything that isn't required is
779 optional, but that's not what is meant here.) This is
780 all the software that you might reasonably want to
781 install if you didn't know what it was and don't have
782 specialized requirements. This is a much larger system
783 and includes the X Window System, a full TeX
784 distribution, and many applications. Note that
785 optional packages should not conflict with each other.
788 <tag><tt>extra</tt></tag>
791 This contains all packages that conflict with others
792 with required, important, standard or optional
793 priorities, or are only likely to be useful if you
794 already know what they are or have specialised
801 Packages must not depend on packages with lower priority
802 values (excluding build-time dependencies). In order to
803 ensure this, the priorities of one or more packages may need
809 <heading>Binary packages</heading>
812 The Debian GNU/Linux distribution is based on the Debian
813 package management system, called <prgn>dpkg</prgn>. Thus,
814 all packages in the Debian distribution must be provided
815 in the <tt>.deb</tt> file format.</p>
819 <heading>The package name</heading>
822 Every package must have a name that's unique within the Debian
826 Package names must consist of lower case letters
827 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
828 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
829 They must be at least two characters long and must contain
834 The package name is part of the file name of the
835 <tt>.deb</tt> file and is included in the control field
841 <heading>The maintainer of a package</heading>
843 Every package must have a Debian maintainer (the
844 maintainer may be one person or a group of people
845 reachable from a common email address, such as a mailing
846 list). The maintainer is responsible for ensuring that
847 the package is placed in the appropriate distributions.
851 The maintainer must be specified in the
852 <tt>Maintainer</tt> control field with their correct name
853 and a working email address. If one person maintains
854 several packages, he/she should try to avoid having
855 different forms of their name and email address in
856 the <tt>Maintainer</tt> fields of those packages.
860 If the maintainer of a package quits from the Debian
861 project, "Debian QA Group"
862 <email>packages@qa.debian.org</email> takes over the
863 maintainership of the package until someone else
864 volunteers for that task. These packages are called
865 <em>orphaned packages</em>.
868 The detailed procedure for doing this gracefully can
869 be found in the Debian Developer's Reference, either
870 in the <tt>developers-reference</tt> package, or on
871 the Debian FTP server
872 <ftpsite>ftp.debian.org</ftpsite> as
873 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
875 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
876 name="Debian Developer's Reference"> webpage.
884 <heading>The description of a package</heading>
887 Every Debian package must have an extended description
888 stored in the appropriate field of the control record.</p>
891 The description should be written so that it gives the
892 system administrator enough information to decide whether
893 to install the package. This description should not just
894 be copied verbatim from the program's documentation.
895 Instructions for configuring or using the package should
896 not be included (that is what installation scripts,
897 manual pages, info files, etc., are for). Copyright
898 statements and other administrivia should not be included
899 either (that is what the copyright file is for).
905 <heading>Dependencies</heading>
908 Every package must specify the dependency information
909 about other packages that are required for the first to
913 For example, a dependency entry must be provided for any
914 shared libraries required by a dynamically-linked executable
915 binary in a package.</p>
918 Packages are not required to declare any dependencies they
919 have on other packages which are marked <tt>Essential</tt>
920 (see below), and should not do so unless they depend on a
921 particular version of that package.</p>
924 Sometimes, a package requires another package to be installed
925 <em>and</em> configured before it can be installed. In this
926 case, you must specify a <tt>Pre-Depends</tt> entry for
930 You should not specify a <tt>Pre-Depends</tt> entry for a
931 package before this has been discussed on the
932 <tt>debian-devel</tt> mailing list and a consensus about
933 doing that has been reached.</p></sect1>
937 <heading>Virtual packages</heading>
940 Sometimes, there are several packages which offer
941 more-or-less the same functionality. In this case, it's
942 useful to define a <em>virtual package</em> whose name
943 describes that common functionality. (The virtual
944 packages only exist logically, not physically; that's why
945 they are called <em>virtual</em>.) The packages with this
946 particular function will then <em>provide</em> the virtual
947 package. Thus, any other package requiring that function
948 can simply depend on the virtual package without having to
949 specify all possible packages individually.</p>
952 All packages should use virtual package names where
953 appropriate, and arrange to create new ones if necessary.
954 They should not use virtual package names (except privately,
955 amongst a cooperating group of packages) unless they have
956 been agreed upon and appear in the list of virtual package
960 The latest version of the authoritative list of virtual
961 package names can be found on
962 <ftpsite>ftp.debian.org</ftpsite> in
963 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
964 or your local mirror. In addition, it is included in the
965 <tt>debian-policy</tt> package. The procedure for updating
966 the list is described at the top of the file.</p></sect1>
970 <heading>Base packages</heading>
973 The packages included in the <tt>base</tt> section have a
974 special function. They form a minimum subset of the Debian
975 GNU/Linux system that is installed before everything else
976 on a new system. Thus, only very few packages are allowed
977 to go into the <tt>base</tt> section to keep the required
978 disk usage very small.</p>
981 Most of these packages will have the priority value
982 <tt>required</tt> or at least <tt>important</tt>, and many
983 of them will be tagged <tt>essential</tt> (see below).</p>
986 You must not place any packages into the <tt>base</tt>
987 section before this has been discussed on the
988 <tt>debian-devel</tt> mailing list and a consensus about
989 doing that has been reached.</p></sect1>
993 <heading>Essential packages</heading>
996 Some packages are tagged <tt>essential</tt>. (They have
997 <tt>Essential: yes</tt> in their package control record.)
998 This flag is used for packages that are <em>essential</em>
1002 Since these packages cannot be easily removed (one has to
1003 specify an extra <em>force option</em> to
1004 <prgn>dpkg</prgn> to do so), this flag must not be used
1005 unless absolutely necessary. A shared library package
1006 must not be tagged <tt>essential</tt>; dependencies will
1007 prevent its premature removal, and we need to be able to
1008 remove it when it has been superseded.
1012 Since dpkg will not prevent upgrading of other packages
1013 while an <tt>essential</tt> package is in an unconfigured
1014 state, all <tt>essential</tt> packages must supply all of
1015 their core functionality even when unconfigured. If the
1016 package cannot satisfy this requirement it must not be
1017 tagged as essential, and any packages depending on this
1018 package must instead have explicit dependency fields as
1023 You must not tag any packages <tt>essential</tt> before
1024 this has been discussed on the <tt>debian-devel</tt>
1025 mailing list and a consensus about doing that has been
1031 <heading>Maintainer scripts</heading>
1034 The package installation scripts should avoid producing
1035 output which it is unnecessary for the user to see and
1036 should rely on <prgn>dpkg</prgn> to stave off boredom on
1037 the part of a user installing many packages. This means,
1038 amongst other things, using the <tt>--quiet</tt> option on
1039 <prgn>install-info</prgn>.</p>
1042 Errors which occur during the execution of an installation
1043 script must be checked and the installation must not
1044 continue after an error.
1048 Note that in general <ref id="scripts"> applies to package
1049 maintainer scripts, too.
1053 You should not use <tt>dpkg-divert</tt> on a file
1054 belonging to another package without consulting the
1055 maintainer of that package first.
1058 All packages which supply an instance of a common command
1059 name (or, in general, filename) should generally use
1060 <prgn>update-alternatives</prgn>, so that they may be
1061 installed together. If <prgn>update-alternatives</prgn>
1062 is not used, then each package must use
1063 <var>Conflicts</var> to ensure that other packages are
1064 de-installed. (In this case, it may be appropriate to
1065 specify a conflict against earlier versions of something
1066 that previously did not use
1067 <prgn>update-alternatives</prgn>; this is an exception to
1068 the usual rule that versioned conflicts should be
1074 <heading>Prompting in maintainer scripts</heading>
1076 Package maintainer scripts may prompt the user if
1077 necessary. Prompting may be accomplished by hand, or by
1078 communicating with a program, such as
1079 <prgn>debconf</prgn>, which conforms to the Debian
1080 Configuration management specification, version 2 or
1081 higher. These are included in the
1082 <file>debconf_specification</file> files in the
1083 <package>debian-policy</package> package.
1084 You may also find this file on the FTP site
1085 <ftpsite>ftp.debian.org</ftpsite> in
1086 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1087 or on your local mirror.
1090 2.5% of Debian packages [see <url
1091 id="http://kitenet.net/programs/debconf/stats/">]
1092 currently use <package>debconf</package> to prompt
1093 the user at install time, and this number is growing
1094 daily. The benefits of using debconf are briefly
1096 id="http://kitenet.net/doc/debconf-doc/introduction.html">;
1097 they include preconfiguration, (mostly)
1098 noninteractive installation, elimination of
1099 redundant prompting, consistency of user interface,
1103 With this increasing number of packages using
1104 <package>debconf</package>, plus the existance of a
1105 nascent second implementation of the Debian
1106 configuration management system
1107 (<package>cdebconf</package>), and the stabalization
1108 of the protocol these things use, the time has
1109 finally come to reflect the use of these things in
1116 Packages which use the Debian Configuration management
1117 specification may contain an additional
1118 <file>config</file> script and a <file>templates</file>
1119 file in their control archive. The <prgn>config</prgn>
1120 script might be run before the <prgn>preinst</prgn>
1121 script, and before the package is unpacked or any of its
1122 dependancies or pre-dependancies are satisfied.
1123 Therefore it must work using only the tools present in
1124 <em>essential</em> packages.
1127 <package>Debconf</package> or another tool that
1128 implements the Debian Configuration management
1129 specification will also be installed, and any
1130 versioned dependencies on it will be satisfied
1131 before preconfiguration begins.
1137 Packages should try to minimize the amount of prompting
1138 they need to do, and they should ensure that the user
1139 will only ever be asked each question once. This means
1140 that packages should try to use appropriate shared
1141 configuration files (such as <tt>/etc/papersize</tt> and
1142 <tt>/etc/news/server</tt>), and shared
1143 <package>debconf</package> variables rather than each
1144 prompting for their own list of required pieces of
1149 It also means that an upgrade should not ask the same
1150 questions again, unless the user has used <tt>dpkg
1151 --purge</tt> to remove the package's configuration. The
1152 answers to configuration questions should be stored in an
1153 appropriate place in <tt>/etc</tt> so that the user can
1154 modify them, and how this has been done should be
1158 If a package has a vitally important piece of
1159 information to pass to the user (such as "don't run me
1160 as I am, you must edit the following configuration files
1161 first or you risk your system emitting badly-formatted
1162 messages"), it should display this in the
1163 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1164 prompt the user to hit return to acknowledge the
1165 message. Copyright messages do not count as vitally
1166 important (they belong in
1167 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1168 neither do instructions on how to use a program (these
1169 should be in on-line documentation, where all the users
1173 Any necessary prompting should almost always be confined
1174 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1175 script. If it is done in the <prgn>postinst</prgn>, it
1176 should be protected with a conditional so that unnecessary
1177 prompting doesn't happen if a package's installation fails
1178 and the <prgn>postinst</prgn> is called with
1179 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1180 <tt>abort-deconfigure</tt>.</p>
1185 <heading>Source packages</heading>
1187 <sect1 id="standardsversion">
1188 <heading>Standards conformance</heading>
1191 In the source package's <tt>Standards-Version</tt> control
1192 field, you must specify the most recent version number of
1193 this policy document with which your package complies.
1194 The current version number is &version;.
1198 This information may be used to file bug reports
1199 automatically if your package becomes too much out of
1204 The version number has four components: major and minor
1205 version number and major and minor patch level. When the
1206 standards change in a way that requires every package to
1207 change the major number will be changed. Significant
1208 changes that will require work in many packages will be
1209 signaled by a change to the minor number. The major patch
1210 level will be changed for any change to the meaning of the
1211 standards, however small; the minor patch level will be
1212 changed when only cosmetic, typographical or other edits
1213 are made which neither change the meaning of the document
1214 nor affect the contents of packages.</p>
1217 Thus only the first three components of the policy version
1218 are significant in the <em>Standards-Version</em> control
1219 field, and so either these three components or the all
1220 four components may be specified.
1223 In the past, people specified the full version number
1224 in the Standards-Version field, for example `2.3.0.0'.
1225 Since minor patch-level changes don't introduce new
1226 policy, it was thought it would be better to relax
1227 policy and only require the first 3 components to be
1228 specified, in this example `2.3.0'. All four
1229 components may still be used if someone wishes to do
1236 You should regularly, and especially if your package has
1237 become out of date, check for the newest Policy Manual
1238 available and update your package, if necessary. When your
1239 package complies with the new standards you should update the
1240 <tt>Standards-Version</tt> source package field and
1244 See the file <tt>upgrading-checklist</tt> for
1245 information about policy which has changed between
1246 different versions of this document.
1254 <heading>Package relationships</heading>
1257 Source packages should specify which binary packages they
1258 require to be installed or not to be installed in order to
1259 build correctly. For example, if building a package
1260 requires a certain compiler, then the compiler should be
1261 specified as a build-time dependency.
1265 It is not necessary to explicitly specify build-time
1266 relationships on a minimal set of packages that are always
1267 needed to compile, link and put in a Debian package a
1268 standard "Hello World!" program written in C or C++. The
1269 required packages are called <em>build-essential</em>, and
1270 an informational list can be found in
1271 <tt>/usr/share/doc/build-essential/list</tt> (which is
1272 contained in the <tt>build-essential</tt>
1276 <list compact="compact">
1278 <p>This allows maintaining the list separately
1279 from the policy documents (the list does not
1280 need the kind of control that the policy
1286 Having a separate package allows one to install
1287 the build-essential packages on a machine, as
1288 well as allowing other packages such as task
1289 packages to require installation of the
1290 build-essential packages using the depends
1296 The separate package allows bug reports against
1297 the list to be categorized separately from
1298 the policy management process in the BTS.
1308 When specifying the set of build-time dependencies, one
1309 should list only those packages explicitly required by the
1310 build. It is not necessary to list packages which are
1311 required merely because some other package in the list of
1312 build-time dependencies depends on them.
1315 The reason for this is that dependencies change, and
1316 you should list all those packages, and <em>only</em>
1317 those packages that <em>you</em> need directly. What
1318 others need is their business. For example, if you
1319 only link against <tt>libimlib</tt>, you will need to
1320 build-depend on <package>libimlib2-dev</package> but
1321 not against any <tt>libjpeg*</tt> packages, even
1322 though <tt>libimlib2-dev</tt> currently depends on
1323 them: installation of <package>libimlib2-dev</package>
1324 will automatically ensure that all of its run-time
1325 dependencies are satisfied.
1331 If build-time dependencies are specified, it must be
1332 possible to build the package and produce working binaries
1333 on a system with only essential and build-essential
1334 packages installed and also those required to satisfy the
1335 build-time relationships (including any implied
1336 relationships). In particular, this means that version
1337 clauses should be used rigorously in build-time
1338 relationships so that one cannot produce bad or
1339 inconsistently configured packages when the relationships
1340 are properly satisfied.
1344 <heading>Changes to the upstream sources</heading>
1347 If changes to the source code are made that are not
1348 specific to the needs of the Debian system, they should be
1349 sent to the upstream authors in whatever form they prefer
1350 so as to be included in the upstream version of the
1354 If you need to configure the package differently for
1355 Debian or for Linux, and the upstream source doesn't
1356 provide a way to do so, you should add such configuration
1357 facilities (for example, a new <prgn>autoconf</prgn> test
1358 or <tt>#define</tt>) and send the patch to the upstream
1359 authors, with the default set to the way they originally
1360 had it. You can then easily override the default in your
1361 <tt>debian/rules</tt> or wherever is appropriate.</p>
1364 You should make sure that the <prgn>configure</prgn> utility
1365 detects the correct architecture specification string
1366 (refer to <ref id="arch-spec"> for details).</p>
1369 If you need to edit a <prgn>Makefile</prgn> where
1370 GNU-style <prgn>configure</prgn> scripts are used, you
1371 should edit the <tt>.in</tt> files rather than editing the
1372 <prgn>Makefile</prgn> directly. This allows the user to
1373 reconfigure the package if necessary. You should
1374 <em>not</em> configure the package and edit the generated
1375 <prgn>Makefile</prgn>! This makes it impossible for
1376 someone else to later reconfigure the package.</p></sect1>
1380 <heading>Documenting your changes</heading>
1383 You should document your changes and updates to the source
1384 package properly in the <tt>debian/changelog</tt> file. (Note
1385 that mistakes in changelogs are usually best rectified by
1386 making a new changelog entry rather than "rewriting history"
1387 by editing old changelog entries.)</p>
1390 In non-experimental packages you must use a format for
1391 <tt>debian/changelog</tt> which is supported by the most
1392 recent released version of <prgn>dpkg</prgn>.
1395 If you wish to use an alternative format, you may do
1396 so as long as you include a parser for it in your
1397 source package. The parser must have an API
1398 compatible with that expected by
1399 <prgn>dpkg-genchanges</prgn> and
1400 <prgn>dpkg-gencontrol</prgn>. If there is general
1401 interest in the new format, you should contact the
1402 <package>dpkg</package> maintainer to have the parser
1403 script for it included in the <prgn>dpkg</prgn>
1404 package. (You will need to agree that the parser and
1405 its manpage may be distributed under the GNU GPL, just
1406 as the rest of `dpkg' is.)
1414 <heading>Error trapping in makefiles</heading>
1417 When <prgn>make</prgn> invokes a command in a makefile
1418 (including your package's upstream makefiles and
1419 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1420 means that <tt>sh</tt>'s usual bad error handling
1421 properties apply: if you include a miniature script as one
1422 of the commands in your makefile you'll find that if you
1423 don't do anything about it then errors are not detected
1424 and <prgn>make</prgn> will blithely continue after
1428 Every time you put more than one shell command (this
1429 includes using a loop) in a makefile command you
1430 must make sure that errors are trapped. For
1431 simple compound commands, such as changing directory and
1432 then running a program, using <tt>&&</tt> rather
1433 than semicolon as a command separator is sufficient. For
1434 more complex commands including most loops and
1435 conditionals you should include a separate <tt>set -e</tt>
1436 command at the start of every makefile command that's
1437 actually one of these miniature shell scripts.</p></sect1>
1441 <heading>Obsolete constructs and libraries</heading>
1444 The include file <prgn><varargs.h></prgn> is
1445 provided to support end-users compiling very old software;
1446 the library <tt>libtermcap</tt> is provided to support the
1447 execution of software which has been linked against it
1448 (either old programs or those such as Netscape which are
1449 only available in binary form).</p>
1452 Debian packages should be patched to use
1453 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1460 <chapt id="controlfields"><heading>Control files and their fields</heading>
1463 Many of the tools in the package management suite manipulate
1464 data represented in a common format, known as <em>control
1465 data</em>. The data is often stored in <em>control
1466 files</em>. Binary and source packages have control files,
1467 and the <tt>.changes</tt> files which control the installation
1468 of uploaded files are also in control file format.
1469 <prgn>Dpkg</prgn>'s internal databases are in a similar
1473 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1476 A control file consists of one or more paragraphs of fields.
1477 The paragraphs are separated by blank lines. Some control
1478 files allow only one paragraph; others allow several, in
1479 which case each paragraph usually refers to a different
1480 package. (For example, in source packages, the first
1481 paragraph refers to the source package, and later paragraphs
1482 refer to binary packages generated from the source.)
1486 Each paragraph consists of a series of data fields; each
1487 field consists of the field name, followed by a colon and
1488 then the data/value associated with that field. It ends at
1489 the end of the line. Horizontal whitespace (spaces and
1490 tabs) may occur immediately before or after the value and is
1491 ignored there; it is conventional to put a single space
1492 after the colon. For example, a field might be:
1493 <example compact="compact">
1496 the field name is <tt>Package</tt> and the field value
1501 Some fields' values may span several lines; in this case
1502 each continuation line <em>must</em> start with a space or
1503 tab. Any trailing spaces or tabs at the end of individual
1504 lines of a field value are ignored.
1508 Except where otherwise stated only a single line of data is
1509 allowed and whitespace is not significant in a field body.
1510 Whitespace must not appear inside names (of packages,
1511 architectures, files or anything else) or version numbers,
1512 or between the characters of multi-character version
1517 Field names are not case-sensitive, but it is usual to
1518 capitalize the field names using mixed case as shown below.
1522 Blank lines, or lines consisting only of spaces and tabs,
1523 are not allowed within field values or between fields - that
1524 would mean a new paragraph.
1529 <sect><heading>List of fields</heading>
1531 This list here is not supposed to be exhaustive. Most fields
1532 are dealt with elsewhere in this document.
1534 <sect1 id="f-Package"><heading><tt>Package</tt>
1538 The name of the binary package. Package names consist of
1539 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1540 (plus, minus and full stop).
1544 They must be at least two characters long and must start
1545 with an alphanumeric character and not be all digits. The
1546 use of lowercase package names is strongly recommended
1547 unless the package you're building (or referring to, in
1548 other fields) is already using uppercase.</p>
1551 <sect1 id="f-Version"><heading><tt>Version</tt>
1555 This lists the source or binary package's version number -
1556 see <ref id="versions">.
1562 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1566 The most recent version of the standards (the policy
1567 manual and associated texts) with which the package
1568 complies. This is updated manually when editing the
1569 source package to conform to newer standards; it can
1570 sometimes be used to tell when a package needs attention.
1571 Its format is described above; see
1572 <ref id="standardsversion">.
1577 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1581 In a <tt>.changes</tt> file or parsed changelog output
1582 this contains the (space-separated) name(s) of the
1583 distribution(s) where this version of the package should
1584 be installed. Valid distributions are determined by the
1585 archive maintainers.
1587 Current distribution names are:
1588 <taglist compact="compact">
1589 <tag><em>stable</em></tag>
1592 This is the current `released' version of Debian
1593 GNU/Linux. Once the distribution is
1594 <em>stable</em> only security fixes and other
1595 major bug fixes are allowed. When changes are
1596 made to this distribution, the release number is
1597 increased (for example: 2.2r1 becomes 2.2r2 then
1602 <tag><em>unstable</em></tag>
1605 This distribution value refers to the
1606 <em>developmental</em> part of the Debian
1607 distribution tree. New packages, new upstream
1608 versions of packages and bug fixes go into the
1609 <em>unstable</em> directory tree. Download from
1610 this distribution at your own risk.
1614 <tag><em>testing</em></tag>
1617 This distribution value refers to the
1618 <em>testing</em> part of the Debian distribution
1619 tree. It receives its packages from the
1620 unstable distribution after a short time lag to
1621 ensure that there are no major issues with the
1622 unstable packages. It is less prone to breakage
1623 than unstable, but still risky. It is not
1624 possible to upload packages directly to
1629 <tag><em>frozen</em></tag>
1632 From time to time, the <em>frozen</em>
1633 distribution enters a state of `code-freeze' in
1634 anticipation of release as a <em>stable</em>
1635 version. During this period of testing only
1636 fixes for existing or newly-discovered bugs will
1637 be allowed. The exact details of this stage are
1638 determined by the Release Manager.
1642 <tag><em>experimental</em></tag>
1645 The packages with this distribution value are
1646 deemed by their maintainers to be high
1647 risk. Oftentimes they represent early beta or
1648 developmental packages from various sources that
1649 the maintainers want people to try, but are not
1650 ready to be a part of the other parts of the
1651 Debian distribution tree. Download at your own
1657 You should list <em>all</em> distributions that the
1658 package should be installed into.
1667 <chapt id="versions"><heading>Version numbering</heading>
1670 Every package has a version number recorded in its
1671 <tt>Version</tt> control file field.
1675 The package management system imposes an ordering on version
1676 numbers, so that it can tell whether packages are being up- or
1677 downgraded and so that package system front end applications
1678 can tell whether a package it finds available is newer than
1679 the one installed on the system. The version number format
1680 has the most significant parts (as far as comparison is
1681 concerned) at the beginning.
1685 The version number format is:
1686 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1690 The three components here are:
1692 <tag><var>epoch</var></tag>
1696 This is a single (generally small) unsigned integer. It
1697 may be omitted, in which case zero is assumed. If it is
1698 omitted then the <var>upstream_version</var> may not
1703 It is provided to allow mistakes in the version numbers
1704 of older versions of a package, and also a package's
1705 previous version numbering schemes, to be left behind.
1710 <tag><var>upstream_version</var></tag>
1714 This is the main part of the version number. It is
1715 usually the version number of the original (`upstream')
1716 package from which the <tt>.deb</tt> file has been made,
1717 if this is applicable. Usually this will be in the same
1718 format as that specified by the upstream author(s);
1719 however, it may need to be reformatted to fit into the
1720 package management system's format and comparison
1725 The comparison behavior of the package management system
1726 with respect to the <var>upstream_version</var> is
1727 described below. The <var>upstream_version</var>
1728 portion of the version number is mandatory.
1732 The <var>upstream_version</var> may contain only
1735 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1737 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1738 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1739 start with a digit. If there is no
1740 <var>debian_revision</var> then hyphens are not allowed;
1741 if there is no <var>epoch</var> then colons are not
1745 <tag><var>debian_revision</var></tag>
1749 This part of the version number specifies the version of
1750 the Debian package based on the upstream version. It
1751 may contain only alphanumerics and the characters
1752 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1753 compared in the same way as the
1754 <var>upstream_version</var> is.
1758 It is optional; if it isn't present then the
1759 <var>upstream_version</var> may not contain a hyphen.
1760 This format represents the case where a piece of
1761 software was written specifically to be turned into a
1762 Debian package, and so there is only one `debianization'
1763 of it and therefore no revision indication is required.
1767 It is conventional to restart the
1768 <var>debian_revision</var> at <tt>1</tt> each time the
1769 <var>upstream_version</var> is increased.
1773 The package management system will break the version
1774 number apart at the last hyphen in the string (if there
1775 is one) to determine the <var>upstream_version</var> and
1776 <var>debian_revision</var>. The absence of a
1777 <var>debian_revision</var> compares earlier than the
1778 presence of one (but note that the
1779 <var>debian_revision</var> is the least significant part
1780 of the version number).
1787 The <var>upstream_version</var> and <var>debian_revision</var>
1788 parts are compared by the package management system using the
1793 The strings are compared from left to right.
1797 First the initial part of each string consisting entirely of
1798 non-digit characters is determined. These two parts (one of
1799 which may be empty) are compared lexically. If a difference
1800 is found it is returned. The lexical comparison is a
1801 comparison of ASCII values modified so that all the letters
1802 sort earlier than all the non-letters.
1806 Then the initial part of the remainder of each string which
1807 consists entirely of digit characters is determined. The
1808 numerical values of these two parts are compared, and any
1809 difference found is returned as the result of the comparison.
1810 For these purposes an empty string (which can only occur at
1811 the end of one or both version strings being compared) counts
1816 These two steps (comparing and removing initial non-digit
1817 strings and initial digit strings) are repeated until a
1818 difference is found or both strings are exhausted.
1822 Note that the purpose of epochs is to allow us to leave behind
1823 mistakes in version numbering, and to cope with situations
1824 where the version numbering scheme changes. It is
1825 <em>not</em> intended to cope with version numbers containing
1826 strings of letters which the package management system cannot
1827 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1828 silly orderings (the author of this manual has heard of a
1829 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1830 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1831 <tt>2</tt> and so forth).
1835 If an upstream package has problematic version numbers they
1836 should be converted to a sane form for use in the
1837 <tt>Version</tt> field.
1841 <heading>Version numbers based on dates</heading>
1843 In general, Debian packages should use the same version
1844 numbers as the upstream sources.</p>
1847 However, in some cases where the upstream version number is
1848 based on a date (e.g., a development `snapshot' release) the
1849 package management system cannot handle these version
1850 numbers without epochs. For example, dpkg will consider
1851 `96May01' to be greater than `96Dec24'.</p>
1854 To prevent having to use epochs for every new upstream
1855 version, the version number should be changed to the
1856 following format in such cases: `19960501', `19961224'. It
1857 is up to the maintainer whether he/she wants to bother the
1858 upstream maintainer to change the version numbers upstream,
1862 Note that other version formats based on dates which are
1863 parsed correctly by the package management system should
1864 <em>not</em> be changed.</p>
1867 Native Debian packages (i.e., packages which have been
1868 written especially for Debian) whose version numbers include
1869 dates should always use the `YYYYMMDD' format.</p>
1873 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1875 <sect id="timestamps"><heading>Time Stamps</heading>
1877 Maintainers should preserve the modification times of the
1878 upstream source files in a package, as far as is reasonably
1882 The rationale is that there is some information conveyed
1883 by knowing the age of the file, for example, you could
1884 recognize that some documentation is very old by looking
1885 at the modification time, so it would be nice if the
1886 modification time of the upstream source would be
1893 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1894 main building script</heading>
1897 This file must be an executable makefile, and contains the
1898 package-specific recipes for compiling the package and
1899 building binary package(s) from the source.
1903 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1904 so that it can be invoked by saying its name rather than
1905 invoking <prgn>make</prgn> explicitly.
1909 Since an interactive <tt>debian/rules</tt> script makes it
1910 impossible to auto-compile that package and also makes it
1911 hard for other people to reproduce the same binary
1912 package, all <em>required targets</em> MUST be
1913 non-interactive. At a minimum, required targets are the
1914 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1915 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1916 <em>binary-indep</em>, and <em>build</em>. It also follows
1917 that any target that these targets depend on must also be
1922 The required and optional targets are as follows:
1924 <tag><tt>build</tt></tag>
1927 This should perform all non-interactive configuration
1928 and compilation of the package. If a package has an
1929 interactive pre-build configuration routine, the
1930 Debianized source package must either be built after
1931 this has taken place (so that the binary package can
1932 be built without rerunning the configuration) or the
1933 configuration routine modified to become
1934 non-interactive. (The latter is preferable if there
1935 are architecture-specific features detected by the
1936 configuration routine.)
1940 For some packages, notably ones where the same
1941 source tree is compiled in different ways to produce
1942 two binary packages, the <prgn>build</prgn> target
1943 does not make much sense. For these packages it is
1944 good enough to provide two (or more) targets
1945 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1946 for each of the ways of building the package, and a
1947 <prgn>build</prgn> target that does nothing. The
1948 <prgn>binary</prgn> target will have to build the
1949 package in each of the possible ways and make the
1950 binary package out of each.
1954 The <prgn>build</prgn> target must not do anything
1955 that might require root privilege.
1959 The <prgn>build</prgn> target may need to run the
1960 <prgn>clean</prgn> target first - see below.
1964 When a package has a configuration and build routine
1965 which takes a long time, or when the makefiles are
1966 poorly designed, or when <prgn>build</prgn> needs to
1967 run <prgn>clean</prgn> first, it is a good idea to
1968 <tt>touch build</tt> when the build process is
1969 complete. This will ensure that if <tt>debian/rules
1970 build</tt> is run again it will not rebuild the whole
1974 Another common way to do this is for <prgn>build</prgn>
1975 to depend on <prgn>build-stamp</prgn> and to do
1976 nothing else, and for the <prgn>build-stamp</prgn>
1977 target to do the building and to <tt>touch
1978 build-stamp</tt> on completion. This is
1979 especially useful if the build routine creates a
1980 file or directory called <tt>build</tt>; in such a
1981 case, <prgn>build</prgn> will need to be listed as
1982 a phony target (i.e., as a dependency of the
1983 <tt>.PHONY</tt> target). See the documentation of
1984 <prgn>make</prgn> for more information on phony
1991 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1992 <tt>binary-indep</tt>
1996 The <prgn>binary</prgn> target must be all that is
1997 necessary for the user to build the binary package(s)
1998 produced from this source package. All of these
1999 targets are required to be non-interactive. It is
2000 split into two parts: <prgn>binary-arch</prgn> builds
2001 the binary packages which are specific to a particular
2002 architecture, and <prgn>binary-indep</prgn> builds
2003 those which are not.
2007 <prgn>binary</prgn> may be (and commonly is) a target
2008 with no commands which simply depends on
2009 <prgn>binary-arch</prgn> and
2010 <prgn>binary-indep</prgn>.
2014 Each <prgn>binary-*</prgn> target should depend on
2015 the <prgn>build</prgn> target, above, so that the
2016 package is built if it has not been already. It
2017 should then create the relevant binary package(s),
2018 using <prgn>dpkg-gencontrol</prgn> to make their
2019 control files and <prgn>dpkg-deb</prgn> to build
2020 them and place them in the parent of the top level
2025 Both the <prgn>binary-arch</prgn> and
2026 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2027 If one of them has nothing to do (which will always be
2028 the case if the source generates only a single binary
2029 package, whether architecture-dependent or not), it
2030 must still exist and must always succeed.
2034 The <prgn>binary</prgn> targets must be invoked as
2038 The <prgn>fakeroot</prgn> package often allows one
2039 to build a package correctly even without being
2046 <tag><tt>clean</tt></tag>
2050 This must undo any effects that the <prgn>build</prgn>
2051 and <prgn>binary</prgn> targets may have had, except
2052 that it should leave alone any output files created in
2053 the parent directory by a run of a <prgn>binary</prgn>
2054 target. This target must be non-interactive.
2058 If a <prgn>build</prgn> file is touched at the end of
2059 the <prgn>build</prgn> target, as suggested above, it
2060 should be removed as the first action that
2061 <prgn>clean</prgn> performs, so that running
2062 <prgn>build</prgn> again after an interrupted
2063 <prgn>clean</prgn> doesn't think that everything is
2068 The <prgn>clean</prgn> target may need to be
2069 invoked as root if <prgn>binary</prgn> has been
2070 invoked since the last <prgn>clean</prgn>, or if
2071 <prgn>build</prgn> has been invoked as root (since
2072 <prgn>build</prgn> may create directories, for
2077 <tag><tt>get-orig-source</tt> (optional)</tag>
2081 This target fetches the most recent version of the
2082 original source package from a canonical archive site
2083 (via FTP or WWW, for example), does any necessary
2084 rearrangement to turn it into the original source
2085 tar file format described below, and leaves it in the
2090 This target may be invoked in any directory, and
2091 should take care to clean up any temporary files it
2096 This target is optional, but providing it if
2097 possible is a good idea.
2103 The <prgn>build</prgn>, <prgn>binary</prgn> and
2104 <prgn>clean</prgn> targets must be invoked with the current
2105 directory being the package's top-level directory.
2110 Additional targets may exist in <tt>debian/rules</tt>,
2111 either as published or undocumented interfaces or for the
2112 package's internal use.
2116 The architectures we build on and build for are determined
2117 by <prgn>make</prgn> variables using the utility
2118 <prgn>dpkg-architecture</prgn>. You can determine the
2119 Debian architecture and the GNU style architecture
2120 specification string for the build machine (the machine type
2121 we are building on) as well as for the host machine (the
2122 machine type we are building for). Here is a list of
2123 supported <prgn>make</prgn> variables:
2124 <list compact="compact">
2126 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2129 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2130 specification string)</p>
2133 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2134 <tt>DEB_*_GNU_TYPE</tt>)</p>
2137 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2138 <tt>DEB_*_GNU_TYPE</tt>)</p>
2140 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2141 the build machine or <tt>HOST</tt> for specification of the
2146 Backward compatibility can be provided in the rules file
2147 by setting the needed variables to suitable default
2148 values; please refer to the documentation of
2149 <prgn>dpkg-architecture</prgn> for details.
2153 It is important to understand that the <tt>DEB_*_ARCH</tt>
2154 string only determines which Debian architecture we are
2155 building on or for. It should not be used to get the CPU
2156 or system information; the GNU style variables should be
2161 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2165 This file records the changes to the Debian-specific parts of the
2169 Though there is nothing stopping an author who is also
2170 the Debian maintainer from using it for all their
2171 changes, it will have to be renamed if the Debian and
2172 upstream maintainers become different people. In such a
2173 case, however, it might be better to maintain the
2174 package as a non-native package.
2180 It has a special format which allows the package building
2181 tools to discover which version of the package is being
2182 built and find out other release-specific information.
2186 That format is a series of entries like this:
2187 <example compact="compact">
2188 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2190 * <var>change details</var>
2191 <var>more change details</var>
2192 * <var>even more change details</var>
2194 -- <var>maintainer name</var> <<var>email address</var>> <var>date</var>
2199 <var>package</var> and <var>version</var> are the source
2200 package name and version number.
2204 <var>distribution(s)</var> lists the distributions where
2205 this version should be installed when it is uploaded - it
2206 is copied to the <tt>Distribution</tt> field in the
2207 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2211 <var>urgency</var> is the value for the <tt>Urgency</tt>
2212 field in the <tt>.changes</tt> file for the upload. It is
2213 not possible to specify an urgency containing commas; commas
2214 are used to separate
2215 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2216 <prgn>dpkg</prgn> changelog format (though there is
2217 currently only one useful <var>keyword</var>,
2221 Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
2222 <tt>high</tt> and <tt>critical</tt>. They have an
2223 effect on how quickly a package will be considered for
2224 inclusion into the <tt>testing</tt> distribution, and
2225 give an indication of the importance of any fixes
2226 included in this upload.
2232 The change details may in fact be any series of lines
2233 starting with at least two spaces, but conventionally each
2234 change starts with an asterisk and a separating space and
2235 continuation lines are indented so as to bring them in
2236 line with the start of the text above. Blank lines may be
2237 used here to separate groups of changes, if desired.
2241 If this upload resolves bugs recorded in the Bug Tracking
2242 System (BTS), they may be automatically closed on the
2243 inclusion of this package into the Debian archive by
2244 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2245 in the change details.
2248 To be precise, the string should match the following
2249 Perl regular expression:
2251 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2253 Then all of the bug numbers listed will be closed by the
2254 archive maintenance script (<prgn>katie</prgn>), or in
2255 the case of an NMU, marked as fixed.
2261 The maintainer name and email address used in the changelog
2262 should be the details of the person uploading <em>this</em>
2263 version. They are <em>not</em> necessarily those of the
2264 usual package maintainer. The information here will be
2265 copied to the <tt>Changed-By</tt> field in the
2266 <tt>.changes</tt> file, and then later used to send an
2267 acknowledgement when the upload has been installed.
2271 The <var>date</var> should be in RFC822 format
2274 This is generated by the <prgn>822-date</prgn>
2277 </footnote>; it should include the time zone specified
2278 numerically, with the time zone name or abbreviation
2279 optionally present as a comment in parentheses.
2283 The first `title' line with the package name should start
2284 at the left hand margin; the `trailer' line with the
2285 maintainer and date details should be preceded by exactly
2286 one space. The maintainer details and the date must be
2287 separated by exactly two spaces.
2290 <sect1><heading>Defining alternative changelog formats</heading>
2293 It is possible to use a different format to the standard
2294 one, by providing a parser for the format you wish to
2298 A changelog parser must not interact with the user at
2304 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2305 and variable substitutions </heading>
2308 When <prgn>dpkg-gencontrol</prgn>,
2309 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2310 generate control files they perform variable substitutions
2311 on their output just before writing it. Variable
2312 substitutions have the form
2313 <tt>${<var>variable-name</var>}</tt>. The optional file
2314 <tt>debian/substvars</tt> contains variable substitutions to
2315 be used; variables can also be set directly from
2316 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2317 source packaging commands, and certain predefined variables
2322 The <tt>debian/substvars</tt> file is usually generated and
2323 modified dynamically by <tt>debian/rules</tt> targets; in
2324 this case it must be removed by the <prgn>clean</prgn>
2329 See <manref name="dpkg-source" section="1"> for full
2330 details about source variable substitutions, including the
2331 format of <tt>debian/substvars</tt>.</p>
2334 <sect id="debianfiles"><heading><tt>debian/files</tt>
2338 This file is not a permanent part of the source tree; it
2339 is used while building packages to record which files are
2340 being generated. <prgn>dpkg-genchanges</prgn> uses it
2341 when it generates a <tt>.changes</tt> file.
2345 It should not exist in a shipped source package, and so it
2346 (and any backup files or temporary files such as
2350 <tt>files.new</tt> is used as a temporary file by
2351 <prgn>dpkg-gencontrol</prgn> and
2352 <prgn>dpkg-distaddfile</prgn> - they write a new
2353 version of <tt>files</tt> here before renaming it,
2354 to avoid leaving a corrupted copy if an error
2357 </footnote>) should be removed by the
2358 <prgn>clean</prgn> target. It may also be wise to
2359 ensure a fresh start by emptying or removing it at the
2360 start of the <prgn>binary</prgn> target.
2364 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2365 package, it adds an entry to <tt>debian/files</tt> for the
2366 <tt>.deb</tt> file that will be created when <tt>dpkg-deb
2367 --build</tt> is run for that binary package. So for most
2368 packages all that needs to be done with this file is to
2369 delete it in the <prgn>clean</prgn> target.
2373 If a package upload includes files besides the source
2374 package and any binary packages whose control files were
2375 made with <prgn>dpkg-gencontrol</prgn> then they should be
2376 placed in the parent of the package's top-level directory
2377 and <prgn>dpkg-distaddfile</prgn> should be called to add
2378 the file to the list in <tt>debian/files</tt>.</p>
2381 <sect id="restrictions"><heading>Restrictions on objects in source packages
2385 The source package may not contain any hard links
2388 This is not currently detected when building source
2389 packages, but only when extracting
2393 Hard links may be permitted at some point in the
2394 future, but would require a fair amount of
2397 </footnote>, device special files, sockets or setuid or
2401 Setgid directories are allowed.
2406 <sect id="descriptions"><heading>Descriptions of packages - the
2407 <tt>Description</tt> field </heading>
2410 The description is intended to describe the program to a user
2411 who has never met it before so that they know whether they
2412 want to install it. It should also give information about the
2413 significant dependencies and conflicts between this package
2414 and others, so that the user knows why these dependencies and
2415 conflicts have been declared.
2418 <sect1><heading>Notes about writing descriptions
2422 The single line synopsis should be kept brief - certainly
2423 under 80 characters.
2427 Do not include the package name in the synopsis line. The
2428 display software knows how to display this already, and you
2429 do not need to state it. Remember that in many situations
2430 the user may only see the synopsis line - make it as
2431 informative as you can.
2435 Do not try to continue the single line synopsis into the
2436 extended description. This will not work correctly when
2437 the full description is displayed, and makes no sense
2438 where only the summary (the single line synopsis) is
2443 The extended description should describe what the package
2444 does and how it relates to the rest of the system (in terms
2445 of, for example, which subsystem it is which part of).
2449 The description field needs to make sense to anyone, even
2450 people who have no idea about any of the things the
2454 The blurb that comes with a program in its
2455 announcements and/or <prgn>README</prgn> files is
2456 rarely suitable for use in a description. It is
2457 usually aimed at people who are already in the
2458 community where the package is used.
2464 Put important information first, both in the synopsis and
2465 extended description. Sometimes only the first part of the
2466 synopsis or of the description will be displayed. You can
2467 assume that there will usually be a way to see the whole
2468 extended description.
2472 You may include information about dependencies and so forth
2473 in the extended description, if you wish.
2477 Do not use tab characters. Their effect is not predictable.
2485 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2486 and installation procedure
2489 <sect><heading>Introduction to package maintainer scripts
2493 It is possible to supply scripts as part of a package which
2494 the package management system will run for you when your
2495 package is installed, upgraded or removed.
2499 These scripts are the files <tt>preinst</tt>,
2500 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2501 control area of the package. They must be proper executable
2502 files; if they are scripts (which is recommended), they must
2503 start with the usual <tt>#!</tt> convention. They should be
2504 readable and executable by anyone, and not world-writable.
2508 The package management system looks at the exit status from
2509 these scripts. It is important that they exit with a
2510 non-zero status if there is an error, so that the package
2511 management system can stop its processing. For shell
2512 scripts this means that you <em>almost always</em> need to
2513 use <tt>set -e</tt> (this is usually true when writing shell
2514 scripts, in fact). It is also important, of course, that
2515 they don't exit with a non-zero status if everything went
2520 When a package is upgraded a combination of the scripts from
2521 the old and new packages is called during the upgrade
2522 procedure. If your scripts are going to be at all
2523 complicated you need to be aware of this, and may need to
2524 check the arguments to your scripts.
2528 Broadly speaking the <prgn>preinst</prgn> is called before
2529 (a particular version of) a package is installed, and the
2530 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2531 before (a version of) a package is removed and the
2532 <prgn>postrm</prgn> afterwards.
2536 Programs called from maintainer scripts should not normally
2537 have a path prepended to them. Before installation is
2538 started, the package management system checks to see if the
2539 programs <prgn>ldconfig</prgn>,
2540 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2541 and <prgn>update-rc.d</prgn> can be found via the
2542 <tt>PATH</tt> environment variable. Those programs, and any
2543 other program that one would expect to be on the
2544 <tt>PATH</tt>, should thus be invoked without an absolute
2545 pathname. Maintainer scripts should also not reset the
2546 <tt>PATH</tt>, though they might choose to modify it by
2547 prepending or appending package-specific directories. These
2548 considerations really apply to all shell scripts.</p>
2552 <heading>Maintainer scripts Idempotency</heading>
2555 It is necessary for the error recovery procedures that the
2556 scripts be idempotent. This means that if it is run
2557 successfully, and then it is called again, it doesn't bomb
2558 out or cause any harm, but just ensures that everything is
2559 the way it ought to be. If the first call failed, or
2560 aborted half way through for some reason, the second call
2561 should merely do the things that were left undone the first
2562 time, if any, and exit with a success status if everything
2566 This is so that if an error occurs, the user interrupts
2567 <prgn>dpkg</prgn> or some other unforeseen circumstance
2568 happens you don't leave the user with a badly-broken
2569 package when <prgn>dpkg</prgn> attempts to repeat the
2577 <heading>Controlling terminal for maintainer scripts</heading>
2580 The maintainer scripts are guaranteed to run with a
2581 controlling terminal and can interact with the user.
2582 If they need to prompt for passwords, do full-screen
2583 interaction or something similar you should do these
2584 things to and from <tt>/dev/tty</tt>, since
2585 <prgn>dpkg</prgn> will at some point redirect scripts'
2586 standard input and output so that it can log the
2587 installation process. Likewise, because these scripts
2588 may be executed with standard output redirected into a
2589 pipe for logging purposes, Perl scripts should set
2590 unbuffered output by setting <tt>$|=1</tt> so that the
2591 output is printed immediately rather than being
2596 Each script should return a zero exit status for
2597 success, or a nonzero one for failure.
2601 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2606 <list compact="compact">
2608 <p><var>new-preinst</var> <tt>install</tt></p>
2611 <p><var>new-preinst</var> <tt>install</tt>
2612 <var>old-version</var></p>
2615 <p><var>new-preinst</var> <tt>upgrade</tt>
2616 <var>old-version</var></p>
2619 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2620 <var>new-version</var>
2626 <list compact="compact">
2628 <p><var>postinst</var> <tt>configure</tt>
2629 <var>most-recently-configured-version</var></p>
2632 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2633 <var>new-version</var></p>
2636 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2637 <tt>in-favour</tt> <var>package</var>
2638 <var>new-version</var></p>
2642 <var>deconfigured's-postinst</var>
2643 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2644 <var>failed-install-package</var> <var>version</var>
2645 <tt>removing</tt> <var>conflicting-package</var>
2652 <list compact="compact">
2654 <p><var>prerm</var> <tt>remove</tt></p>
2657 <p><var>old-prerm</var> <tt>upgrade</tt>
2658 <var>new-version</var></p>
2661 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2662 <var>old-version</var></p>
2665 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2666 <tt>in-favour</tt> <var>package</var>
2667 <var>new-version</var></p>
2671 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2672 <tt>in-favour</tt> <var>package-being-installed</var>
2673 <var>version</var> <tt>removing</tt>
2674 <var>conflicting-package</var>
2681 <list compact="compact">
2683 <p><var>postrm</var> <tt>remove</tt></p>
2686 <p><var>postrm</var> <tt>purge</tt></p>
2690 <var>old-postrm</var> <tt>upgrade</tt>
2691 <var>new-version</var></p>
2694 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2695 <var>old-version</var></p>
2698 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2701 <p><var>new-postrm</var> <tt>abort-install</tt>
2702 <var>old-version</var></p>
2705 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2706 <var>old-version</var></p>
2710 <var>disappearer's-postrm</var> <tt>disappear</tt>
2711 <var>overwriter</var>
2712 <var>overwriter-version</var></p></item>
2717 <sect id="unpackphase"><heading>Details of unpack phase of
2718 installation or upgrade
2722 The procedure on installation/upgrade/overwrite/disappear
2723 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2724 stage of <tt>dpkg --install</tt>) is as follows. In each
2725 case, if a major error occurs (unless listed below) the
2726 actions are, in general, run backwards - this means that the
2727 maintainer scripts are run with different arguments in
2728 reverse order. These are the `error unwind' calls listed
2736 <p>If a version of the package is already
2738 <example compact="compact">
2739 <var>old-prerm</var> upgrade <var>new-version</var>
2744 If the script runs but exits with a non-zero
2745 exit status, <prgn>dpkg</prgn> will attempt:
2746 <example compact="compact">
2747 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2749 Error unwind, for both the above cases:
2750 <example compact="compact">
2751 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2759 <p>If a `conflicting' package is being removed at the same time:
2763 If any packages depended on that conflicting
2764 package and <tt>--auto-deconfigure</tt> is
2765 specified, call, for each such package:
2766 <example compact="compact">
2767 <var>deconfigured's-prerm</var> deconfigure \
2768 in-favour <var>package-being-installed</var> <var>version</var> \
2769 removing <var>conflicting-package</var> <var>version</var>
2772 <example compact="compact">
2773 <var>deconfigured's-postinst</var> abort-deconfigure \
2774 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2775 removing <var>conflicting-package</var> <var>version</var>
2777 The deconfigured packages are marked as
2778 requiring configuration, so that if
2779 <tt>--install</tt> is used they will be
2780 configured again if possible.</p>
2783 <p>To prepare for removal of the conflicting package, call:
2784 <example compact="compact">
2785 <var>conflictor's-prerm</var> remove \
2786 in-favour <var>package</var> <var>new-version</var>
2789 <example compact="compact">
2790 <var>conflictor's-postinst</var> abort-remove \
2791 in-favour <var>package</var> <var>new-version</var>
2802 <p>If the package is being upgraded, call:
2803 <example compact="compact">
2804 <var>new-preinst</var> upgrade <var>old-version</var>
2809 Otherwise, if the package had some configuration
2810 files from a previous version installed (i.e., it
2811 is in the `configuration files only' state):
2812 <example compact="compact">
2813 <var>new-preinst</var> install <var>old-version</var>
2817 <p>Otherwise (i.e., the package was completely purged):
2818 <example compact="compact">
2819 <var>new-preinst</var> install
2821 Error unwind actions, respectively:
2822 <example compact="compact">
2823 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2824 <var>new-postrm</var> abort-install <var>old-version</var>
2825 <var>new-postrm</var> abort-install
2835 The new package's files are unpacked, overwriting any
2836 that may be on the system already, for example any
2837 from the old version of the same package or from
2838 another package. Backups of the old files are kept
2839 temporarily, and if anything goes wrong the package
2840 management system will attempt to put them back as
2841 part of the error unwind.
2845 It is an error for a package to contains files which
2846 are on the system in another package, unless
2847 <tt>Replaces</tt> is used (see <ref id="replaces">).
2849 The following paragraph is not currently the case:
2850 Currently the <tt>- - force-overwrite</tt> flag is
2851 enabled, downgrading it to a warning, but this may not
2857 It is a more serious error for a package to contain a
2858 plain file or other kind of non-directory where another
2859 package has a directory (again, unless
2860 <tt>Replaces</tt> is used). This error can be
2861 overridden if desired using
2862 <tt>--force-overwrite-dir</tt>, but this is not
2867 Packages which overwrite each other's files produce
2868 behavior which, though deterministic, is hard for the
2869 system administrator to understand. It can easily
2870 lead to `missing' programs if, for example, a package
2871 is installed which overwrites a file from another
2872 package, and is then removed again.
2875 Part of the problem is due to what is arguably a
2876 bug in <prgn>dpkg</prgn>.
2882 A directory will never be replaced by a symbolic link
2883 to a directory or vice versa; instead, the existing
2884 state (symlink or not) will be left alone and
2885 <prgn>dpkg</prgn> will follow the symlink if there is
2893 <p>If the package is being upgraded, call
2894 <example compact="compact">
2895 <var>old-postrm</var> upgrade <var>new-version</var>
2899 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2900 <example compact="compact">
2901 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2903 Error unwind, for both cases:
2904 <example compact="compact">
2905 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2911 This is the point of no return - if
2912 <prgn>dpkg</prgn> gets this far, it won't back off
2913 past this point if an error occurs. This will
2914 leave the package in a fairly bad state, which
2915 will require a successful re-installation to clear
2916 up, but it's when <prgn>dpkg</prgn> starts doing
2917 things that are irreversible.
2922 Any files which were in the old version of the package
2923 but not in the new are removed.</p>
2926 <p>The new file list replaces the old.</p>
2929 <p>The new maintainer scripts replace the old.</p>
2933 <p>Any packages all of whose files have been overwritten during the
2934 installation, and which aren't required for
2935 dependencies, are considered to have been removed.
2936 For each such package
2939 <p><prgn>dpkg</prgn> calls:
2940 <example compact="compact">
2941 <var>disappearer's-postrm</var> disappear \
2942 <var>overwriter</var> <var>overwriter-version</var>
2947 <p>The package's maintainer scripts are removed.
2952 It is noted in the status database as being in a
2953 sane state, namely not installed (any conffiles
2954 it may have are ignored, rather than being
2955 removed by <prgn>dpkg</prgn>). Note that
2956 disappearing packages do not have their prerm
2957 called, because <prgn>dpkg</prgn> doesn't know
2958 in advance that the package is going to
2967 Any files in the package we're unpacking that are also
2968 listed in the file lists of other packages are removed
2969 from those lists. (This will lobotomize the file list
2970 of the `conflicting' package if there is one.)
2975 The backup files made during installation, above, are
2982 The new package's status is now sane, and recorded as
2987 Here is another point of no return - if the
2988 conflicting package's removal fails we do not unwind
2989 the rest of the installation; the conflicting package
2990 is left in a half-removed limbo.
2996 If there was a conflicting package we go and do the
2997 removal actions (described below), starting with the
2998 removal of the conflicting package's files (any that
2999 are also in the package being installed have already
3000 been removed from the conflicting package's file list,
3001 and so do not get removed now).
3008 <sect><heading>Details of configuration</heading>
3011 When we configure a package (this happens with <tt>dpkg
3012 --install</tt>, or with <tt>--configure</tt>), we first
3013 update any <tt>conffile</tt>s and then call:
3014 <example compact="compact">
3015 <var>postinst</var> configure <var>most-recently-configured-version</var>
3020 No attempt is made to unwind after errors during
3025 If there is no most recently configured version
3026 <prgn>dpkg</prgn> will pass a null argument; older versions
3027 of dpkg may pass <tt><unknown></tt> (including the
3028 angle brackets) in this case. Even older ones do not pass a
3029 second argument at all, under any circumstances.
3033 <sect><heading>Details of removal and/or configuration purging
3040 <example compact="compact">
3041 <var>prerm</var> remove
3047 The package's files are removed (except <tt>conffile</tt>s).
3052 <example compact="compact">
3053 <var>postrm</var> remove
3059 All the maintainer scripts except the <tt>postrm</tt>
3064 If we aren't purging the package we stop here. Note
3065 that packages which have no <tt>postrm</tt> and no
3066 <tt>conffile</tt>s are automatically purged when
3067 removed, as there is no difference except for the
3068 <prgn>dpkg</prgn> status.</p>
3072 The conffiles and any backup files (<tt>~</tt>-files,
3073 <tt>#*#</tt> files, <tt>%</tt>-files,
3074 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3078 <example compact="compact">
3079 <var>postrm</var> purge
3084 <p>The package's file list is removed.</p>
3087 No attempt is made to unwind after errors during
3094 <chapt id="relationships"><heading>Declaring relationships between
3098 Packages can declare in their control file that they have
3099 certain relationships to other packages - for example, that
3100 they may not be installed at the same time as certain other
3101 packages, and/or that they depend on the presence of others,
3102 or that they should overwrite files in certain other packages
3107 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3108 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3109 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3110 control file fields.
3114 Source packages may declare relationships to binary packages,
3115 saying that they require certain binary packages to be
3116 installed or absent at the time of building the package.
3120 This is done using the <tt>Build-Depends</tt>,
3121 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3122 <tt>Build-Conflicts-Indep</tt> control file fields.
3125 <sect id="depsyntax"><heading>Syntax of relationship fields
3129 These fields all have a uniform syntax. They are a list of
3130 package names separated by commas.
3134 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3135 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3136 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3137 control file fields of the package, which declare
3138 dependencies on other packages, the package names listed may
3139 also include lists of alternative package names, separated
3140 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3141 if any one of the alternative packages is installed, that
3142 part of the dependency is considered to be satisfied.
3146 All of the fields except for <tt>Provides</tt> may restrict
3147 their applicability to particular versions of each named
3148 package. This is done in parentheses after each individual
3149 package name; the parentheses should contain a relation from
3150 the list below followed by a version number, in the format
3151 described in <ref id="versions">.
3155 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3156 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3157 strictly earlier, earlier or equal, exactly equal, later or
3158 equal and strictly later, respectively. The deprecated
3159 forms <tt><</tt> and <tt>></tt> were used to mean
3160 earlier/later or equal, rather than strictly earlier/later,
3161 so they should not appear in new packages (though
3162 <prgn>dpkg</prgn> still supports them).
3166 Whitespace may appear at any point in the version
3167 specification subject to the rules in <ref
3168 id="controlsyntax">, and must appear where it's necessary to
3169 disambiguate; it is not otherwise significant. For
3170 consistency and in case of future changes to
3171 <prgn>dpkg</prgn> it is recommended that a single space be
3172 used after a version relationship and before a version
3173 number; it is also conventional to put a single space after
3174 each comma, on either side of each vertical bar, and before
3175 each open parenthesis.
3179 For example, a list of dependencies might appear as:
3180 <example compact="compact">
3183 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3188 All fields that specify build-time relationships
3189 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3190 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3191 may be restricted to a certain set of architectures. This
3192 is indicated in brackets after each individual package name and
3193 the optional version specification. The brackets enclose a
3194 list of Debian architecture names separated by whitespace.
3195 Exclamation marks may be prepended to each of the names.
3196 (It is not permitted for some names to be prepended with
3197 exclamation marks and others not.) If the current Debian
3198 host architecture is not in this list and there are no
3199 exclamation marks in the list, or it is in the list with a
3200 prepended exclamation mark, the package name and the
3201 associated version specification are ignored completely for
3202 the purposes of defining the relationships.
3207 <example compact="compact">
3209 Build-Depends-Indep: texinfo
3210 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3211 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3217 <heading>Binary Dependencies - <tt>Depends</tt>,
3218 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3219 <tt>Pre-Depends</tt>
3223 These five fields are used to declare a dependency
3224 relationship by one package on another. They appear in the
3225 depending package's control file.
3229 A <tt>Depends</tt> field takes effect <em>only</em> when a
3230 package is to be configured. It does not prevent a package
3231 being on the system in an unconfigured state while its
3232 dependencies are unsatisfied, and it is possible to replace
3233 a package whose dependencies are satisfied and which is
3234 properly installed with a different version whose
3235 dependencies are not and cannot be satisfied; when this is
3236 done the depending package will be left unconfigured (since
3237 attempts to configure it will give errors) and will not
3238 function properly. If it is necessary, a
3239 <tt>Pre-Depends</tt> field can be used, which has a partial
3240 effect even when a package is being unpacked, as explained
3241 in detail below. (The other three dependency fields,
3242 <tt>Recommends</tt>, <tt>Suggests</tt> and
3243 <tt>Enhances</tt>, are only used by the various front-ends
3244 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3248 For this reason packages in an installation run are usually
3249 all unpacked first and all configured later; this gives
3250 later versions of packages with dependencies on later
3251 versions of other packages the opportunity to have their
3252 dependencies satisfied.
3256 The <tt>Depends</tt> field thus allows package maintainers
3257 to impose an order in which packages should be configured.
3261 The meaning of the five dependency fields is as follows:
3263 <tag><tt>Depends</tt></tag>
3267 This declares an absolute dependency. A package will
3268 not be configured unless all of the packages listed in
3269 its <tt>Depends</tt> field have been correctly
3274 The <tt>Depends</tt> field should be used if the
3275 depended-on package is required for the depending
3276 package to provide a significant amount of
3280 The <tt>Depends</tt> field should also be used if the
3281 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3282 <prgn>postrm</prgn> scripts require the package to be
3283 present in order to run. Note, however, that the
3284 <prgn>postrm</prgn> cannot rely on any non-essential
3285 packages to be present during the <tt>purge</tt>
3289 <tag><tt>Recommends</tt></tag>
3291 <p>This declares a strong, but not absolute, dependency.
3295 The <tt>Recommends</tt> field should list packages
3296 that would be found together with this one in all but
3297 unusual installations.</p>
3300 <tag><tt>Suggests</tt></tag>
3304 This is used to declare that one package may be more
3305 useful with one or more others. Using this field
3306 tells the packaging system and the user that the
3307 listed packages are related to this one and can
3308 perhaps enhance its usefulness, but that installing
3309 this one without them is perfectly reasonable.
3313 <tag><tt>Enhances</tt></tag>
3316 This field is similar to Suggests but works in the
3317 opposite direction. It is used to declare that a
3318 package can enhance the functionality of another
3323 <tag><tt>Pre-Depends</tt></tag>
3327 This field is like <tt>Depends</tt>, except that it
3328 also forces <prgn>dpkg</prgn> to complete installation
3329 of the packages named before even starting the
3330 installation of the package which declares the
3331 pre-dependency, as follows:
3335 When a package declaring a pre-dependency is about to
3336 be <em>unpacked</em> the pre-dependency can be
3337 satisfied if the depended-on package is either fully
3338 configured, <em>or even if</em> the depended-on
3339 package(s) are only unpacked or half-configured,
3340 provided that they have been configured correctly at
3341 some point in the past (and not removed or partially
3342 removed since). In this case, both the
3343 previously-configured and currently unpacked or
3344 half-configured versions must satisfy any version
3345 clause in the <tt>Pre-Depends</tt> field.
3349 When the package declaring a pre-dependency is about
3350 to be <em>configured</em>, the pre-dependency will be
3351 treated as a normal <tt>Depends</tt>, that is, it will
3352 be considered satisfied only if the depended-on
3353 package has been correctly configured.
3357 <tt>Pre-Depends</tt> should be used sparingly,
3358 preferably only by packages whose premature upgrade or
3359 installation would hamper the ability of the system to
3360 continue with any upgrade that might be in progress.
3364 <tt>Pre-Depends</tt> are also required if the
3365 <prgn>preinst</prgn> script depends on the named
3366 package. It is best to avoid this situation if
3372 When selecting which level of dependency to use you should
3373 consider how important the depended-on package is to the
3374 functionality of the one declaring the dependency. Some
3375 packages are composed of components of varying degrees of
3376 importance. Such a package should list using
3377 <tt>Depends</tt> the package(s) which are required by the
3378 more important components. The other components'
3379 requirements may be mentioned as Suggestions or
3380 Recommendations, as appropriate to the components' relative
3385 <sect id="conflicts"><heading>Conflicting binary packages -
3386 <tt>Conflicts</tt></heading>
3389 When one binary package declares a conflict with another
3390 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3391 refuse to allow them to be installed on the system at the
3396 If one package is to be installed, the other must be removed
3397 first - if the package being installed is marked as
3398 replacing (see <ref id="replaces">) the one on the system,
3399 or the one on the system is marked as deselected, or both
3400 packages are marked <tt>Essential</tt>, then
3401 <prgn>dpkg</prgn> will automatically remove the package
3402 which is causing the conflict, otherwise it will halt the
3403 installation of the new package with an error. This
3404 mechanism is specifically designed to produce an error when
3405 the installed package is <tt>Essential</tt>, but the new
3410 A package will not cause a conflict merely because its
3411 configuration files are still installed; it must be at least
3416 A special exception is made for packages which declare a
3417 conflict with their own package name, or with a virtual
3418 package which they provide (see below): this does not
3419 prevent their installation, and allows a package to conflict
3420 with others providing a replacement for it. You use this
3421 feature when you want the package in question to be the only
3422 package providing some feature.
3426 A <tt>Conflicts</tt> entry should almost never have an
3427 `earlier than' version clause. This would prevent
3428 <prgn>dpkg</prgn> from upgrading or installing the package
3429 which declared such a conflict until the upgrade or removal
3430 of the conflicted-with package had been completed.
3434 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3438 As well as the names of actual (`concrete') packages, the
3439 package relationship fields <tt>Depends</tt>,
3440 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3441 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3442 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3443 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3444 may mention `virtual packages'.
3448 A <em>virtual package</em> is one which appears in the
3449 <tt>Provides</tt> control file field of another package.
3450 The effect is as if the package(s) which provide a
3451 particular virtual package name had been listed by name
3452 everywhere the virtual package name appears.
3456 If there are both a real and a virtual package of the same
3457 name then the dependency may be satisfied (or the conflict
3458 caused) by either the real package or any of the virtual
3459 packages which provide it. This is so that, for example,
3461 <example compact="compact">
3465 and someone else releases an enhanced version of the
3466 <tt>bar</tt> package (for example, a non-US variant), they
3468 <example compact="compact">
3472 and the <tt>bar-plus</tt> package will now also satisfy the
3473 dependency for the <tt>foo</tt> package.
3477 If a dependency or a conflict has a version number attached
3478 then only real packages will be considered to see whether
3479 the relationship is satisfied (or the prohibition violated,
3480 for a conflict) - it is assumed that a real package which
3481 provides the virtual package is not of the `right' version.
3482 So, a <tt>Provides</tt> field may not contain version
3483 numbers, and the version number of the concrete package
3484 which provides a particular virtual package will not be
3485 looked at when considering a dependency on or conflict with
3486 the virtual package name.
3490 It is likely that the ability will be added in a future
3491 release of <prgn>dpkg</prgn> to specify a version number for
3492 each virtual package it provides. This feature is not yet
3493 present, however, and is expected to be used only
3498 If you want to specify which of a set of real packages
3499 should be the default to satisfy a particular dependency on
3500 a virtual package, you should list the real package as an
3501 alternative before the virtual one.
3506 <sect id="replaces"><heading>Overwriting files and replacing
3507 packages - <tt>Replaces</tt></heading>
3510 The <tt>Replaces</tt> control file field has two distinct
3511 purposes, which come into play in different situations.
3514 <sect1><heading>Overwriting files in other packages</heading>
3517 Firstly, as mentioned before, it is usually an error for a
3518 package to contain files which are on the system in
3523 However, if the overwriting package declares that it
3524 <tt>Replaces</tt> the one containing the file being
3525 overwritten, then <prgn>dpkg</prgn> will replace the file
3526 from the old package with that from the new. The file
3527 will no longer be listed as `owned' by the old package.
3531 If a package is completely replaced in this way, so that
3532 <prgn>dpkg</prgn> does not know of any files it still
3533 contains, it is considered to have `disappeared'. It will
3534 be marked as not wanted on the system (selected for
3535 removal) and not installed. Any <tt>conffile</tt>s
3536 details noted for the package will be ignored, as they
3537 will have been taken over by the overwriting package. The
3538 package's <prgn>postrm</prgn> script will be run with a
3539 special argument to allow the package to do any final
3540 cleanup required. See <ref id="mscriptsinstact">.
3544 If an installed package, <tt>foo</tt> say, declares that
3545 it replaces another, <tt>bar</tt>, and an attempt is made
3546 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3547 files in the <tt>bar</tt> package which would overwrite
3548 those already present in <tt>foo</tt>. This is so that
3549 you can install an older version of a package without
3554 For this usage of <tt>Replaces</tt>, virtual packages (see
3555 <ref id="virtual">) are not considered when looking at a
3556 <tt>Replaces</tt> field - the packages declared as being
3557 replaced must be mentioned by their real names.
3561 Furthermore, this usage of <tt>Replaces</tt> only takes
3562 effect when both packages are at least partially on the
3563 system at once, so that it can only happen if they do not
3564 conflict or if the conflict has been overridden.
3569 <sect1><heading>Replacing whole packages, forcing their
3573 Secondly, <tt>Replaces</tt> allows the packaging system to
3574 resolve which package should be removed when there is a
3575 conflict - see <ref id="conflicts">. This usage only
3576 takes effect when the two packages <em>do</em> conflict,
3577 so that the two usages of this field do not interfere with
3582 In this situation, the package declared as being replaced
3583 can be a virtual package, so for example, all mail
3584 transport agents (MTAs) would have the following fields in
3585 their control files:
3586 <example compact="compact">
3587 Provides: mail-transport-agent
3588 Conflicts: mail-transport-agent
3589 Replaces: mail-transport-agent
3591 ensuring that only one MTA can be installed at any one
3596 <sect><heading>Relationships between source and binary packages -
3597 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3598 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3602 A source package may declare a dependency or a conflict on a
3603 binary package, indicating which packages are required to be
3604 present on the system in order to build the binary packages
3605 from the source package. This is done with the control file
3606 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3607 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3608 The dependencies and conflicts they define must be satisfied
3609 (as defined earlier for binary packages) in order to invoke
3610 the targets in <tt>debian/rules</tt>, as follows:
3613 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3616 The <tt>Build-Depends</tt> and
3617 <tt>Build-Conflicts</tt> fields must be satisfied when
3618 any of the following targets is invoked:
3619 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3620 and <tt>binary-indep</tt>.
3623 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3626 The <tt>Build-Depends-Indep</tt> and
3627 <tt>Build-Conflicts-Indep</tt> fields must be
3628 satisfied when any of the following targets is
3629 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3640 <chapt id="conffiles"><heading>Configuration file handling
3644 This chapter has been superseded by <ref id="config files">.
3648 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3651 Packages containing shared libraries must be constructed with
3652 a little care to make sure that the shared library is always
3653 available. This is especially important for packages whose
3654 shared libraries are vitally important, such as the C library
3655 (currently <tt>libc6</tt>).
3659 Firstly, the package should install the shared libraries under
3660 their normal names. For example, the <tt>libgdbmg1</tt>
3661 package should install <tt>libgdbm.so.1.7.3</tt> as
3662 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3663 renamed or re-linked by any <prgn>prerm</prgn> or
3664 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3665 of renaming things safely without affecting running programs,
3666 and attempts to interfere with this are likely to lead to
3671 Secondly, the package should include the symbolic link that
3672 <prgn>ldconfig</prgn> would create for the shared libraries.
3673 For example, the <prgn>libgdbmg1</prgn> package should include
3674 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3675 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3676 linker (for example <prgn>ld.so</prgn> or
3677 <prgn>ld-linux.so.*</prgn>) can find the library between the
3678 time that <prgn>dpkg</prgn> installs it and the time that
3679 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3683 The package management system requires the library to be
3684 placed before the symbolic link pointing to it in the
3685 <tt>.deb</tt> file. This is so that when
3686 <prgn>dpkg</prgn> comes to install the symlink
3687 (overwriting the previous symlink pointing at an older
3688 version of the library), the new shared library is already
3689 in place. In the past, this was achieved by creating the
3690 library in the temporary packaging directory before
3691 creating the symlink. Unfortunately, this was not always
3692 effective, since the building of the tar file in the
3693 <tt>.deb</tt> depended on the behavior of the underlying
3694 file system. Some file systems (such as reiserfs) reorder
3695 the files so that the order of creation is forgotten.
3696 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3697 will reorder the files itself as necessary when building a
3698 package. Thus it is no longer important to concern
3699 oneself with the order of file creation.
3705 Thirdly, the associated development package should contain a
3706 symlink for the shared library without a version number. For
3707 example, the <tt>libgdbmg1-dev</tt> package should include a
3708 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3709 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3710 linker (<prgn>ld</prgn>) when compiling packages, as it will
3711 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3715 Any package installing shared libraries in one of the default
3716 library directories of the dynamic linker (which are currently
3717 <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
3718 listed in <tt>/etc/ld.so.conf</tt>
3722 <list compact="compact">
3723 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3724 <item><p>/usr/local/lib</p></item>
3725 <item><p>/usr/lib/libc5-compat</p></item>
3726 <item><p>/lib/libc5-compat</p></item>
3727 <item><p>/usr/X11R6/lib</p></item>
3731 must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3732 script if and only if the first argument is <tt>configure</tt>
3733 and should call it in the <prgn>postrm</prgn> script if the
3734 first argument is <tt>remove</tt>.
3738 However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
3739 <em>must not</em> call <prgn>ldconfig</prgn> in the case where
3740 the package is being upgraded (see <ref id="unpackphase"> for
3741 details), as <prgn>ldconfig</prgn> will see the temporary
3742 names that <prgn>dpkg</prgn> uses for the files while it is
3743 installing them and will make the shared library links point
3744 to them, just before <prgn>dpkg</prgn> continues the
3745 installation and renames the temporary files!
3749 <heading>Handling shared library dependencies - the
3750 <tt>shlibs</tt> system</heading>
3753 If a package contains a binary or library which links to a
3754 shared library, we must ensure that when the package is
3755 installed on the system, all of the libraries needed are
3756 also installed. This requirement led to the creation of the
3757 <tt>shlibs</tt> system, which is very simple in its design:
3758 any package which <em>provides</em> a shared library also
3759 provides information on the package dependencies required to
3760 ensure the presence of this library, and any package which
3761 <em>uses</em> a shared library uses this information to
3762 determine the dependencies it requires. The files which
3763 contain the mapping from shared libraries to the necessary
3764 dependency information are called <tt>shlibs</tt> files.
3768 Thus, when a package is built which contains any shared
3769 libraries, it must provide a <tt>shlibs</tt> file for other
3770 packages to use, and when a package is built which contains
3771 any shared libraries or compiled binaries, it must run
3772 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3773 libraries used and hence the dependencies needed by this
3777 In the past, the shared libraries linked to were
3778 determined by calling <prgn>ldd</prgn>, but now
3779 <prgn>objdump</prgn> to do this. The only change this
3780 makes to package building is that
3781 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3782 libraries, whereas in the past this was unnecessary.
3783 The rest of this footnote explains the advantage that
3788 We say that a binary <tt>foo</tt> <em>directly</em> uses
3789 a library <tt>libbar</tt> if it is explicitly linked
3790 with that library (that is, it uses the flag
3791 <tt>-lbar</tt> during the linking stage). Other
3792 libraries that are needed by <tt>libbar</tt> are linked
3793 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3794 linker will load them automatically when it loads
3795 <tt>libbar</tt>. A package should needs to depend on
3796 the libraries it directly uses, and the dependencies for
3797 those libraries should automatically pull in the other
3802 Unfortunately, the <prgn>ldd</prgn> program shows both
3803 the directly and indirectly used libraries, meaning that
3804 the dependencies determined included both direct and
3805 indirect dependencies. The use of <prgn>objdump</prgn>
3806 avoids this problem by determining only the directly
3811 A good example of where this helps is the following. We
3812 could update <tt>libimlib</tt> with a new version that
3813 supports a new graphics format called dgf (but retaining
3814 the same major version number). If we used the old
3815 <prgn>ldd</prgn> method, every package that uses
3816 <tt>libimlib</tt> would need to be recompiled so it
3817 would also depend on <tt>libdgf</tt> or it wouldn't run
3818 due to missing symbols. However with the new system,
3819 packages using <tt>libimlib</tt> can rely on
3820 <tt>libimlib</tt> itself having the dependency on
3821 <tt>libdgf</tt> and so they would not need rebuilding.
3827 In the following sections, we will first describe where the
3828 various <tt>shlibs</tt> files are to be found, then how to
3829 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3830 <tt>shlibs</tt> file format and how to create them if your
3831 package contains a shared library.
3835 <sect><heading>The <tt>shlibs</tt> files present on the system
3839 There are several places where <tt>shlibs</tt> files are
3840 found. The following list gives them in the order in which
3841 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3842 one which gives the required information is used.)
3848 <p><tt>debian/shlibs.local</tt></p>
3850 This lists overrides for this package. Its use is
3851 described below (see <ref id="shlibslocal">).
3856 <p><tt>/etc/dpkg/shlibs.override</tt></p>
3858 This lists global overrides. This list is normally
3859 empty. It is maintained by the local system
3865 <p><tt>DEBIAN/shlibs</tt> files in the `build directory'</p>
3867 When packages are being built, any
3868 <tt>debian/shlibs</tt> files are copied into the
3869 control file area of the temporary build directory and
3870 given the name <tt>shlibs</tt>. These files give
3871 details of any shared libraries included in the
3875 An example may help here. Let us say that the
3876 source package <tt>foo</tt> generates two binary
3877 packages, <tt>libfoo2</tt> and
3878 <tt>foo-runtime</tt>. When building the binary
3879 packages, the two packages are created in the
3880 directories <tt>debian/libfoo2</tt> and
3881 <tt>debian/foo-runtime</tt> respectively.
3882 (<tt>debian/tmp</tt> could be used instead of one
3883 of these.) Since <tt>libfoo2</tt> provides the
3884 <tt>libfoo</tt> shared library, it will require a
3885 <tt>shlibs</tt> file, which will be installed in
3886 <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
3888 <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>. Then
3889 when <prgn>dpkg-shlibdeps</prgn> is run on the
3891 <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
3893 <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
3894 determine whether <tt>foo-prog</tt>'s library
3895 dependencies are satisfied by any of the libraries
3896 provided by <tt>libfoo2</tt>. For this reason,
3897 <prgn>dpkg-shlibdeps</prgn> must only be run once
3898 all of the individual binary packages'
3899 <tt>shlibs</tt> files have been installed into the
3907 <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p>
3909 These are the <tt>shlibs</tt> files corresponding to
3910 all of the packages installed on the system, and are
3911 maintained by the relevant package maintainers.
3916 <p><tt>/etc/dpkg/shlibs.default</tt></p>
3918 This file lists any shared libraries whose packages
3919 have failed to provide correct <tt>shlibs</tt> files.
3920 It was used when the <tt>shlibs</tt> setup was first
3921 introduced, but it is now normally empty. It is
3922 maintained by the <tt>dpkg</tt> maintainer.
3930 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
3931 <tt>shlibs</tt> files</heading>
3934 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3935 <tt>debian/rules</tt> file. If your package contains only
3936 compiled binaries and libraries (but no scripts), you can
3937 use a command such as:
3938 <example compact="compact">
3939 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
3940 debian/tmp/usr/lib/*
3942 Otherwise, you will need to explicitly list the compiled
3943 binaries and libraries.
3946 If you are using <tt>debhelper</tt>, the
3947 <prgn>dh_shlibdeps</prgn> program will do this work for
3948 you. It will also correctly handle multi-binary
3955 This command puts the dependency information into the
3956 <tt>debian/substvars</tt> file, which is then used by
3957 <prgn>dpkg-gencontrol</prgn>. You will need to place a
3958 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
3959 field in the control file for this to work.
3963 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3964 done. If it does complain you might need to create your own
3965 <tt>debian/shlibs.local</tt> file, as explained below (see
3966 <ref id="shlibslocal">).
3970 If you have multiple binary packages, you will need to call
3971 <prgn>dpkg-shlibdeps</prgn> on each one which contains
3972 compiled libraries or binaries. In such a case, you will
3973 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
3974 utilities to specify a different <tt>substvars</tt> file.
3975 For more details on this and other options, see <manref
3976 name="dpkg-shlibdeps" section="1">.
3980 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3984 Each <tt>shlibs</tt> file has the same format. Lines
3985 beginning with <tt>#</tt> are considered to be commments and
3986 are ignored. Each line is of the form:
3987 <example compact="compact">
3988 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
3993 We will explain this by reference to the example of the
3994 <tt>zlib1g</tt> package, which (at the time of writing)
3995 installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
3999 <var>library-name</var> is the name of the shared library,
4000 in this case <tt>libz</tt>. (This must match the name part
4001 of the soname, see below.)
4005 <var>soname-version-number</var> is the version part of the
4006 soname of the library. The soname is the thing that must
4007 exactly match for the library to be recognized by the
4008 dynamic linker, and is usually of the form
4009 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4010 example, <tt>libz.so.1</tt>.
4013 This can be determined using the command
4014 <example compact="compact">
4015 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4019 The version part is the part which comes after
4020 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4024 <var>dependencies</var> has the same syntax as a dependency
4025 field in a binary package control file. It should give
4026 details of which packages are required to satisfy a binary
4027 built against the version of the library contained in the
4028 package. See <ref id="depsyntax"> for details.
4032 In our example, if the first version of the <tt>zlib1g</tt>
4033 package which contained a minor number of at least
4034 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4035 <tt>shlibs</tt> entry for this library could say:
4036 <example compact="compact">
4037 libz 1 zlib1g (>= 1:1.1.3)
4039 The version-specific dependency is to avoid warnings from
4040 the dynamic linker about using older shared libraries with
4046 <heading>Providing a <tt>shlibs</tt> file</heading>
4049 If your package provides a shared library, you should create
4050 a <tt>shlibs</tt> file following the format described above.
4051 It is usual to call this file <tt>debian/shlibs</tt> (but if
4052 you have multiple binary packages, you might want to call it
4053 <tt>debian/shlibs.<var>package</var></tt> instead). Then
4054 let <tt>debian/rules</tt> install it in the control area:
4055 <example compact="compact">
4056 install -m644 debian/shlibs debian/tmp/DEBIAN
4058 or, in the case of a multi-binary package:
4059 <example compact="compact">
4060 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4062 An alternative way of doing this is to create the
4063 <tt>shlibs</tt> file in the control area directly from
4064 <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
4068 This is what <prgn>dh_makeshlibs</prgn> in the
4069 <tt>debhelper</tt> suite does.
4072 since the <tt>debian/shlibs</tt> file itself is ignored by
4073 <prgn>dpkg-shlibdeps</prgn>.
4077 As <prgn>dpkg-shlibdeps</prgn> reads the
4078 <tt>DEBIAN/shlibs</tt> files in all of the binary packages
4079 being built from this source package, all of the
4080 <tt>DEBIAN/shlibs</tt> files should be installed before
4081 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4086 <sect id="shlibslocal">
4087 <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
4090 This file is intended only as a <em>temporary</em> fix if
4091 your binaries or libraries depend on a library whose package
4092 does not yet provide a correct <tt>shlibs</tt> file.
4096 We will assume that you are trying to package a binary
4097 <tt>foo</tt>. When you try running
4098 <prgn>dpkg-shlibdeps</prgn> you get the following error
4099 message (<tt>-O</tt> displays the dependency information on
4100 <tt>stdout</tt> instead of writing it to
4101 <tt>debian/substvars</tt>, and the lines have been wrapped
4102 for ease of reading):
4103 <example compact="compact">
4104 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4105 dpkg-shlibdeps: warning: unable to find dependency
4106 information for shared library libbar (soname 1,
4107 path /usr/lib/libbar.so.1, dependency field Depends)
4108 shlibs:Depends=libc6 (>= 2.2.2-2)
4110 You can then run <prgn>ldd</prgn> on the binary to find the
4111 full location of the library concerned:
4112 <example compact="compact">
4114 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4115 libc.so.6 => /lib/libc.so.6 (0x40032000)
4116 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4118 So the <prgn>foo</prgn> binary depends on the
4119 <prgn>libbar</prgn> shared library, but no package seems to
4120 provide a <tt>*.shlibs</tt> file handling
4121 <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>. Let's
4122 determine the package responsible:
4123 <example compact="compact">
4124 $ dpkg -S /usr/lib/libbar.so.1
4125 bar1: /usr/lib/libbar.so.1
4126 $ dpkg -s bar1 | grep Version
4129 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4130 is the one we are using. Now we can file a bug against the
4131 <tt>bar1</tt> package and create our own
4132 <tt>debian/shlibs.local</tt> to locally fix the problem.
4133 Including the following line into your
4134 <tt>debian/shlibs.local</tt> file:
4135 <example compact="compact">
4136 libbar 1 bar1 (>= 1.0-1)
4138 should allow the package build to work.
4142 As soon as the maintainer of <tt>bar1</tt> provides a
4143 correct <tt>shlibs</tt> file, you should remove this line
4144 from your <tt>debian/shlibs.local</tt> file. (You should
4145 probably also then have a versioned <tt>Build-Depends</tt>
4146 on <tt>bar1</tt> to help ensure that others do not have the
4147 same problem building your package.)
4152 <chapt><heading>The Operating System</heading>
4155 <heading>File system hierarchy</heading>
4159 <heading>Linux File system Structure</heading>
4162 The location of all installed files and directories must
4163 comply with the Linux File system Hierarchy Standard
4164 (FHS). The latest version of this document can be found
4165 alongside this manual or on
4166 <url id="http://www.pathname.com/fhs/">.
4167 Specific questions about following the standard may be
4168 asked on <prgn>debian-devel</prgn>, or referred to Daniel
4169 Quinlan, the FHS coordinator, at
4170 <email>quinlan@pathname.com</email>.</p></sect1>
4174 <heading>Site-specific programs</heading>
4177 As mandated by the FHS, packages must not place any
4178 files in <tt>/usr/local</tt>, either by putting them in
4179 the file system archive to be unpacked by <prgn>dpkg</prgn>
4180 or by manipulating them in their maintainer scripts.</p>
4183 However, the package may create empty directories below
4184 <tt>/usr/local</tt> so that the system administrator knows
4185 where to place site-specific files. These directories
4186 should be removed on package removal if they are
4190 Note, that this applies only to directories <em>below</em>
4191 <tt>/usr/local</tt>, not <em>in</em>
4192 <tt>/usr/local</tt>. Packages must not create sub-directories
4193 in the directory <tt>/usr/local</tt> itself, except those listed in
4194 FHS, section 4.5. However, you may create directories
4195 below them as you wish. You must not remove any of the
4196 directories listed in 4.5, even if you created them.</p>
4199 Since <tt>/usr/local</tt> can be mounted read-only from a
4200 remote server, these directories must be created and
4201 removed by the <tt>postinst</tt> and <tt>prerm</tt>
4202 maintainer scripts. These scripts must not fail if either
4203 of these operations fail. (In the future, it will be
4204 possible to tell <prgn>dpkg</prgn> not to unpack files
4205 matching certain patterns, so that the directories can be
4206 included in the <tt>.deb</tt> packages and system
4207 administrators who do not wish these directories in
4208 /usr/local do not need to have them.)</p>
4211 For example, the <prgn>emacs</prgn> package will contain
4212 <example compact="compact">
4213 mkdir -p /usr/local/lib/emacs/site-lisp || true
4215 in the <tt>postinst</tt> script, and
4216 <example compact="compact">
4217 rmdir /usr/local/lib/emacs/site-lisp || true
4218 rmdir /usr/local/lib/emacs || true
4220 in the <tt>prerm</tt> script.</p>
4223 If you do create a directory in <tt>/usr/local</tt> for
4224 local additions to a package, you should ensure that
4225 settings in <tt>/usr/local</tt> take precedence over the
4226 equivalents in <tt>/usr</tt>.</p>
4229 However, because '/usr/local' and its contents are for
4230 exclusive use of the local administrator, a package must
4231 not rely on the presence or absence of files or
4232 directories in '/usr/local' for normal operation.</p>
4235 The <tt>/usr/local</tt> directory itself and all the
4236 subdirectories created by the package should (by default) have
4237 permissions 2775 (group-writable and set-group-id) and be
4238 owned by <tt>root.staff</tt>.</p>
4241 <heading>The system-wide mail directory</heading>
4243 The system-wide mail directory is <tt>/var/mail</tt>. This
4244 directory is part of the base system and should not owned
4245 by any particular mail agents. The use of the old
4246 location <tt>/var/spool/mail</tt> is deprecated, even
4247 though the spool may still be physically located there.
4248 To maintain partial upgrade compatibility for systems
4249 which have <tt>/var/spool/mail</tt> as their physical mail
4250 spool, packages using <tt>/var/mail</tt> must depend on
4251 either <package>libc6</package> (>= 2.1.3-13), or on
4252 <package>base-files</package> (>= 2.2.0), or on later
4253 versions of either one of these packages.
4262 <heading>Users and groups</heading>
4265 The Debian system can be configured to use either plain or
4266 shadow passwords.</p>
4269 Some user ids (UIDs) and group ids (GIDs) are reserved
4270 globally for use by certain packages. Because some packages
4271 need to include files which are owned by these users or
4272 groups, or need the ids compiled into binaries, these ids
4273 must be used on any Debian system only for the purpose for
4274 which they are allocated. This is a serious restriction, and
4275 we should avoid getting in the way of local administration
4276 policies. In particular, many sites allocate users and/or
4277 local system groups starting at 100.</p>
4280 Apart from this we should have dynamically allocated ids,
4281 which should by default be arranged in some sensible
4282 order, but the behavior should be configurable.</p>
4285 Packages other than <tt>base-passwd</tt> must not modify
4286 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4287 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4290 The UID and GID ranges are as follows:
4295 Globally allocated by the Debian project, the
4296 same on every Debian system. These ids will appear in
4297 the <tt>passwd</tt> and <tt>group</tt> files of all
4298 Debian systems, new ids in this range being added
4299 automatically as the <tt>base-passwd</tt> package is
4303 Packages which need a single statically allocated uid
4304 or gid should use one of these; their maintainers
4305 should ask the <tt>base-passwd</tt> maintainer for
4312 Dynamically allocated system users and groups.
4313 Packages which need a user or group, but can have this
4314 user or group allocated dynamically and differently on
4315 each system, should use `<tt>adduser --system</tt>' to
4316 create the group and/or user. <prgn>adduser</prgn>
4317 will check for the existence of the user or group, and
4318 if necessary choose an unused id based on the ranges
4319 specified in <tt>adduser.conf</tt>.</p></item>
4322 <tag>1000-29999:</tag>
4325 Dynamically allocated user accounts. By default
4326 <prgn>adduser</prgn> will choose UIDs and GIDs for
4327 user accounts in this range, though
4328 <tt>adduser.conf</tt> may be used to modify this
4332 <tag>30000-59999:</tag>
4334 <p>Reserved.</p></item>
4337 <tag>60000-64999:</tag>
4340 Globally allocated by the Debian project, but only
4341 created on demand. The ids are allocated centrally and
4342 statically, but the actual accounts are only created
4343 on users' systems on demand.</p>
4346 These ids are for packages which are obscure or which
4347 require many statically-allocated ids. These packages
4348 should check for and create the accounts in
4349 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4350 <prgn>adduser</prgn> if it has this facility) if
4351 necessary. Packages which are likely to require
4352 further allocations should have a `hole' left after
4353 them in the allocation, to give them room to
4357 <tag>65000-65533:</tag>
4359 <p>Reserved.</p></item>
4364 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4365 to the group `<tt>nogroup</tt>.'</p></item>
4371 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4372 because it is the error return sentinel value.</p>
4377 <sect id="sysvinit">
4378 <heading>System run levels</heading>
4381 <sect1 id="/etc/init.d">
4382 <heading>Introduction</heading>
4385 The <tt>/etc/init.d</tt> directory contains the scripts
4386 executed by <prgn>init</prgn> at boot time and when init
4387 state (or `runlevel') is changed (see <manref name="init"
4391 There are at least two different, yet functionally
4392 equivalent, ways of handling these scripts. For the sake
4393 of simplicity, this document describes only the symbolic
4394 link method. However, it must not be assumed by maintainer
4395 scripts that this method is being used, and any automated
4396 manipulation of the various runlevel behaviours by
4397 maintainer scripts must be performed using `update-rc.d'
4398 as described below and not by manually installing or
4399 removing symlinks. For information on the
4400 implementation details of the other method, implemented in
4401 the <tt>file-rc</tt> package, please refer to the
4402 documentation of that package.</p>
4405 These scripts are referenced by symbolic links in
4406 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4407 changing runlevels, <prgn>init</prgn> looks in the
4408 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4409 it should execute, where <var>n</var> is the runlevel that
4410 is being changed to, or `S' for the boot-up scripts.</p>
4413 The names of the links all have the form
4414 <tt>S<var>mm</var><var>script</var></tt> or
4415 <tt>K<var>mm</var><var>script</var></tt> where
4416 <var>mm</var> is a two-digit number and <var>script</var>
4417 is the name of the script (this should be the same as the
4418 name of the actual script in <tt>/etc/init.d</tt>.</p>
4421 When <prgn>init</prgn> changes runlevel first the targets
4422 of the links whose names starting with a <tt>K</tt> are
4423 executed, each with the single argument <tt>stop</tt>,
4424 followed by the scripts prefixed with an <tt>S</tt>, each
4425 with the single argument <tt>start</tt>. The <tt>K</tt>
4426 links are responsible for killing services and the
4427 <tt>S</tt> link for starting services upon entering the
4431 For example, if we are changing from runlevel 2 to
4432 runlevel 3, init will first execute all of the <tt>K</tt>
4433 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4434 all of the <tt>S</tt> prefixed scripts. The links
4435 starting with <tt>K</tt> will cause the referred-to file
4436 to be executed with an argument of <tt>stop</tt>, and the
4437 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4440 The two-digit number <var>mm</var> is used to decide which
4441 order to start and stop things in: low-numbered links have
4442 their scripts run first. For example, the <tt>K20</tt>
4443 scripts will be executed before the <tt>K30</tt> scripts.
4444 This is used when a certain service must be started before
4445 another. For example, the name server <prgn>bind</prgn>
4446 might need to be started before the news server
4447 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4448 access lists. In this case, the script that starts
4449 <prgn>bind</prgn> would have a lower number than the
4450 script that starts <prgn>inn</prgn> so that it runs first:
4451 <example compact="compact">
4459 <heading>Writing the scripts</heading>
4462 Packages that include daemons for system services should
4463 place scripts in <tt>/etc/init.d</tt> to start or stop
4464 services at boot time or during a change of runlevel.
4465 These scripts should be named
4466 <tt>/etc/init.d/<var>package</var></tt>, and they should
4467 accept one argument, saying what to do:
4470 <tag><tt>start</tt></tag>
4471 <item><p>start the service,</p></item>
4473 <tag><tt>stop</tt></tag>
4474 <item><p>stop the service,</p></item>
4476 <tag><tt>restart</tt></tag>
4477 <item><p>stop and restart the service,</p></item>
4479 <tag><tt>reload</tt></tag>
4480 <item><p>cause the configuration of the service to be
4481 reloaded without actually stopping and restarting
4482 the service,</p></item>
4484 <tag><tt>force-reload</tt></tag> <item><p>cause the
4485 configuration to be reloaded if the service supports
4486 this, otherwise restart the service.</p></item>
4489 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4490 <tt>force-reload</tt> options should be supported by all
4491 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4492 option is optional.</p>
4495 The <tt>init.d</tt> scripts should ensure that they will
4496 behave sensibly if invoked with <tt>start</tt> when the
4497 service is already running, or with <tt>stop</tt> when it
4498 isn't, and that they don't kill unfortunately-named user
4499 processes. The best way to achieve this is usually to use
4500 <prgn>start-stop-daemon</prgn>.</p>
4503 If a service reloads its configuration automatically (as
4504 in the case of <prgn>cron</prgn>, for example), the
4505 <tt>reload</tt> option of the <tt>init.d</tt> script
4506 should behave as if the configuration has been reloaded
4510 These scripts should not fail obscurely when the
4511 configuration files remain but the package has been
4512 removed, as configuration files remain on the system after
4513 the package has been removed. Only when <prgn>dpkg</prgn>
4514 is executed with the <tt>--purge</tt> option will
4515 configuration files be removed. In particular, the init
4516 script itself is usually a configuration file (see
4517 <ref id="init.d notes">), and will remain on the system if
4518 the package is removed but not purged. Therefore, you
4519 should include a <tt>test</tt> statement at the top of the
4521 <example compact="compact">
4522 test -f <var>program-executed-later-in-script</var> || exit 0
4526 Often there are some values in the `<tt>init.d</tt>'
4527 scripts that a system administrator will frequently want
4528 to change. While the scripts are frequently conffiles,
4529 modifying them requires that the administrator merge in
4530 their changes each time the package is upgraded and the
4531 conffile changes. To ease the burden on the system
4532 administrator, such configurable values should not be
4533 placed directly in the script. Instead, they should be
4534 placed in a file in `<tt>/etc/default</tt>', which
4535 typically will have the same base name as the
4536 `<tt>init.d</tt>' script. This extra file can be sourced
4537 by the script when the script runs. It must contain only
4538 variable settings and comments.
4542 To ensure that vital configurable values are always
4543 available, the `<tt>init.d</tt>' script should set default
4544 values for each of the shell variables it uses before
4545 sourcing the <tt>/etc/default/</tt> file. Also, since the
4546 `<tt>/etc/default/</tt>' file is often a conffile, the
4547 `<tt>init.d</tt>' script must behave sensibly without
4548 failing if it is deleted.
4554 <heading>Managing the links</heading>
4557 The program <prgn>update-rc.d</prgn> is provided to make
4558 it easier for package maintainers to arrange for the
4559 proper creation and removal of
4560 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4561 functional equivalent if another method is being used.
4562 This may be used by maintainers in their packages'
4563 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4566 You must use this script to make changes to
4567 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4568 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4569 in the actual archive or manually create or remove the
4570 symbolic links in maintainer scripts. (The latter will
4571 fail if an alternative method of maintaining runlevel
4572 information is being used.)</p>
4575 By default <prgn>update-rc.d</prgn> will start services in
4576 each of the multi-user state runlevels (2, 3, 4, and 5)
4577 and stop them in the halt runlevel (0), the single-user
4578 runlevel (1) and the reboot runlevel (6). The system
4579 administrator will have the opportunity to customize
4580 runlevels by either running <prgn>update-rc.d</prgn>, by
4581 simply adding, moving, or removing the symbolic links in
4582 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4583 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4584 <tt>file-rc</tt> method is being used.</p>
4587 To get the default behavior for your package, put in your
4588 <tt>postinst</tt> script
4589 <example compact="compact">
4590 update-rc.d <var>package</var> defaults >/dev/null
4592 and in your <tt>postrm</tt>
4593 <example compact="compact">
4594 if [ purge = "$1" ]; then
4595 update-rc.d <var>package</var> remove >/dev/null
4600 This will use a default sequence number of 20. If it does
4601 not matter when or in which order the script is run, use
4602 this default. If it does, then you should talk to the
4603 maintainer of the <prgn>sysvinit</prgn> package or post to
4604 <tt>debian-devel</tt>, and they will help you choose a
4608 For more information about using <tt>update-rc.d</tt>,
4609 please consult its manpage <manref name="update-rc.d"
4610 section="8">.</p></sect1>
4614 <heading>Boot-time initialization</heading>
4617 There used to be another directory, <tt>/etc/rc.boot</tt>,
4618 which contained scripts which were run once per machine
4619 boot. This has been deprecated in favour of links from
4620 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4621 described in <ref id="/etc/init.d">. Packages must not
4622 place files in <tt>/etc/rc.boot</tt>.</p>
4624 <sect1 id="init.d notes">
4625 <heading>Notes</heading>
4628 <em>Do not</em> include the
4629 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4630 <tt>.deb</tt> file system archive! <em>This will cause
4631 problems!</em> You must create them with
4632 <prgn>update-rc.d</prgn>, as above.</p>
4635 <em>Do not</em> include the
4636 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4637 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4638 problems!</em> You should, however, treat the
4639 <tt>/etc/init.d</tt> scripts as configuration files,
4640 either by marking them as conffiles or managing them
4641 correctly in the maintainer scripts (see
4642 <ref id="config files">). (This is important since we want
4643 to give the local system administrator the chance to adapt
4644 the scripts to the local system, e.g., to disable a
4645 service without de-installing the package, or to specify
4646 some special command line options when starting a
4647 service, while making sure her changes aren't lost during
4648 the next package upgrade.)</p>
4652 <heading>Example</heading>
4655 The <prgn>bind</prgn> DNS (nameserver) package wants to
4656 make sure that the nameserver is running in multiuser
4657 runlevels, and is properly shut down with the system. It
4658 puts a script in <tt>/etc/init.d</tt>, naming the script
4659 appropriately <tt>bind</tt>. As you can see, the script
4660 interprets the argument <tt>reload</tt> to send the
4661 nameserver a <tt>HUP</tt> signal (causing it to reload its
4662 configuration); this way the user can say
4663 <tt>/etc/init.d/bind reload</tt> to reload the name
4664 server. The script has one configurable value, which can
4665 be used to pass parameters to the named program at
4670 <example compact="compact">
4673 # Original version by Robert Leslie
4674 # <rob@mars.org>, edited by iwj and cs
4676 test -x /usr/sbin/named || exit 0
4678 # Source defaults file.
4680 if [ -f /etc/default/bind ]; then
4687 echo -n "Starting domain name service: named"
4688 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4693 echo -n "Stopping domain name service: named"
4694 start-stop-daemon --stop --quiet \
4695 --pidfile /var/run/named.pid --exec /usr/sbin/named
4699 echo -n "Restarting domain name service: named"
4700 start-stop-daemon --stop --quiet \
4701 --pidfile /var/run/named.pid --exec /usr/sbin/named
4702 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4706 force-reload|reload)
4707 echo -n "Reloading configuration of domain name service: named"
4708 start-stop-daemon --stop --signal 1 --quiet \
4709 --pidfile /var/run/named.pid --exec /usr/sbin/named
4713 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4723 Complementing the above init script is a file
4724 '<tt>/etc/default/bind</tt>', which contains configurable
4725 parameters used by the script.
4728 <example compact="compact">
4729 # Specified parameters to pass to named. See named(8).
4730 # You may uncomment the following line, and edit to taste.
4736 Another example on which to base your <tt>/etc/init.d</tt>
4737 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4740 If this package is happy with the default setup from
4741 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4742 and having named running in all runlevels, it can say in
4743 its <tt>postinst</tt>:
4744 <example compact="compact">
4745 update-rc.d bind defaults >/dev/null
4747 And in its <tt>postrm</tt>, to remove the links when the
4749 <example compact="compact">
4750 if [ purge = "$1" ]; then
4751 update-rc.d bind remove >/dev/null
4757 <heading>Cron jobs</heading>
4760 Packages must not modify the configuration file
4761 <tt>/etc/crontab</tt>, and they must not modify the files in
4762 <tt>/var/spool/cron/crontabs</tt>.</p>
4765 If a package wants to install a job that has to be executed
4766 via cron, it should place a file with the name of the
4767 package in one of the following directories:
4768 <example compact="compact">
4773 As these directory names imply, the files within them are
4774 executed on a daily, weekly, or monthly basis,
4775 respectively. The exact times are listed in
4776 <tt>/etc/crontab</tt>.</p>
4779 All files installed in any of these directories must be
4780 scripts (shell scripts, Perl scripts, etc.) so that they can
4781 easily be modified by the local system administrator. In
4782 addition, they should be treated as configuration files.</p>
4785 If a certain job has to be executed more frequently than
4786 daily, the package should install a file
4787 <tt>/etc/cron.d/<var>package</var></tt>. This file uses
4788 the same syntax as <tt>/etc/crontab</tt> and is processed by
4789 <prgn>cron</prgn> automatically. The file must also be
4790 treated as a configuration file. (Note, that entries in the
4791 <tt>/etc/cron.d</tt> directory are not handled by
4792 <prgn>anacron</prgn>. Thus, you should only use this
4793 directory for jobs which may be skipped if the system is not
4797 The scripts or crontab entries in these directories should
4798 check if all necessary programs are installed before they
4799 try to execute them. Otherwise, problems will arise when a
4800 package was removed but not purged since configuration files
4801 are kept on the system in this situation.</p>
4805 <heading>Console messages</heading>
4808 This section describes different formats for messages
4809 written to standard output by the <tt>/etc/init.d</tt>
4810 scripts. The intent is to improve the consistency of
4811 Debian's startup and shutdown look and feel.</p>
4814 Please look very careful at the details. We want to get the
4815 messages to look exactly the same way concerning spaces,
4816 punctuation, and case of letters.</p>
4819 Here is a list of overall rules that you should use when you
4820 create output messages. They can be useful if you have a
4821 non-standard message that isn't covered in the sections
4828 Every message should cover one line, start with a
4829 capital letter and end with a period `.'.</p></item>
4834 If you want to express that the computer is working on
4835 something (performing a specific task, not starting or
4836 stopping a program), we use an ``ellipsis'', namely
4837 three dots `...'. Note that we don't insert spaces in
4838 front of or behind the dots. If the task has been
4839 completed we write `done.' and a line feed.</p></item>
4844 Design your messages as if the computer is telling you
4845 what he is doing (let him be polite :-) but don't
4846 mention ``him'' directly. For example, if you think
4848 <example compact="compact">
4849 I'm starting network daemons: nfsd mountd.
4852 <example compact="compact">
4853 Starting network daemons: nfsd mountd.
4861 The following formats should be used</p>
4866 <p>when daemons get started.</p>
4869 Use this format if your script starts one or more
4870 daemons. The output should look like this (a single
4871 line, no leading spaces):
4872 <example compact="compact">
4873 Starting <description>: <daemon-1> ... <daemon-n>.
4875 The <description> should describe the subsystem
4876 the daemon or set of daemons are part of, while
4877 <daemon-1> up to <daemon-n> denote each
4878 daemon's name (typically the file name of the
4882 For example, the output of /etc/init.d/lpd would look like:
4883 <example compact="compact">
4884 Starting printer spooler: lpd.
4888 This can be achieved by saying
4889 <example compact="compact">
4890 echo -n "Starting printer spooler: lpd"
4891 start-stop-daemon --start --quiet lpd
4894 in the script. If you have more than one daemon to
4895 start, you should do the following:
4896 <example compact="compact">
4897 echo -n "Starting remote file system services:"
4898 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4899 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4900 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4903 This makes it possible for the user to see what takes
4904 so long and when the final daemon has been
4905 started. You should be careful where to put spaces: In the
4906 example above the system administrator can easily
4907 comment out a line if he don't wants to start a
4908 specific daemon, while the displayed message still
4914 <p>when something needs to be configured.</p>
4917 If you have to set up different parameters of the
4918 system upon boot up, you should use this format:
4919 <example compact="compact">
4920 Setting <parameter> to `<value>'.
4925 You can use the following echo statement to get the quotes right:
4926 <example compact="compact">
4927 echo "Setting DNS domainname to \`"value"'."
4932 Note that the left quotation mark (`) is different
4938 <p>when a daemon is stopped.</p>
4941 When you stop a daemon you should issue a message
4942 similar to the startup message, except that `Starting'
4943 is replaced with `Stopping'.</p>
4946 So stopping the printer daemon will like like this:
4947 <example compact="compact">
4948 Stopping printer spooler: lpd.
4949 </example></p></item>
4952 <p>when something is executed.</p>
4955 There are several examples where you have to run a
4956 program at system startup or shutdown to perform a
4957 specific task. For example, setting the system's clock
4958 via `netdate' or killing all processes when the system
4959 comes down. Your message should like this:
4960 <example compact="compact">
4961 Doing something very useful...done.
4963 You should print the `done.' right after the job has been completed,
4964 so that the user gets informed why he has to wait. You can get this
4966 <example compact="compact">
4967 echo -n "Doing something very useful..."
4976 <p>when the configuration is reloaded.</p>
4979 When a daemon is forced to reload its configuration
4980 files you should use the following format:
4981 <example compact="compact">
4982 Reloading <daemon's-name> configuration...done.
4988 <p>when none of the above rules apply.</p>
4991 If you have to print a message that doesn't fit into
4992 the styles described above, you can use something
4993 appropriate, but please have a look at the overall
5002 <heading>Menus</heading>
5005 Menu entries should follow the current menu policy as
5006 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
5007 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
5008 or your local mirror. In addition, it is included in the
5009 <tt>debian-policy</tt> package.
5013 The Debian <tt>menu</tt> packages provides a unique
5014 interface between packages providing applications and
5015 documents, and <em>menu programs</em> (either X window
5016 managers or text-based menu programs as
5017 <prgn>pdmenu</prgn>).</p>
5020 All packages that provide applications that need not be
5021 passed any special command line arguments for normal
5022 operation should register a menu entry for those
5023 applications, so that users of the <tt>menu</tt> package
5024 will automatically get menu entries in their window
5025 managers, as well in shells like <tt>pdmenu</tt>.</p>
5028 Please refer to the <em>Debian Menu System</em> document
5029 that comes with the <tt>menu</tt> package for information
5030 about how to register your applications and web
5036 <heading>Multimedia handlers</heading>
5039 Packages which provide the ability to view/show/play,
5040 compose, edit or print MIME types should register themselves
5041 as such following the current MIME support policy as defined
5042 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
5043 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
5044 or your local mirror. In addition, it is included in the
5045 <tt>debian-policy</tt> package.
5049 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
5050 mechanism for encoding files and data streams and providing
5051 meta-information about them, in particular their type (e.g.
5052 audio or video) and format (e.g. PNG, HTML, MP3).
5056 Registration of MIME type handlers allows programs like mail
5057 user agents and web browsers to to invoke these handlers to
5058 view, edit or display MIME types they don't support
5064 <heading>Keyboard configuration</heading>
5067 To achieve a consistent keyboard configuration (i.e., all
5068 applications interpret a keyboard event the same way) all
5069 programs in the Debian distribution must be configured to
5070 comply with the following guidelines.</p>
5073 Here is a list that contains certain keys and their interpretation:
5076 <tag><tt><--</tt></tag>
5077 <item><p>delete the character to the left of the cursor</p></item>
5079 <tag><tt>Delete</tt></tag>
5080 <item><p>delete the character to the right of the cursor</p></item>
5082 <tag><tt>Control+H</tt></tag>
5083 <item><p>emacs: the help prefix</p></item>
5086 The interpretation of any keyboard events should be independent
5087 of the terminal that's used, be it a virtual console, an X
5088 terminal emulator, an rlogin/telnet session, etc.</p>
5091 The following list explains how the different programs
5092 should be set up to achieve this:</p>
5096 <item><p>`<tt><--</tt>' generates KB_Backspace in
5099 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
5103 X translations are set up to make KB_Backspace
5104 generate ASCII DEL, and to make KB_Delete generate
5105 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
5106 the `delete character' key). This must be done by
5107 loading the resources using xrdb on all local X
5108 displays, not using the application defaults, so that
5109 the translation resources used correspond to the
5110 xmodmap settings.</p></item>
5114 The Linux console is configured to make
5115 `<tt><--</tt>' generate DEL, and `Delete' generate
5116 <tt>ESC [ 3 ~</tt> (this is the case at the
5120 X applications are configured so that Backspace
5121 deletes left, and Delete deletes right. Motif
5122 applications already work like this.</p></item>
5124 <item><p>stty erase <tt>^?</tt> .</p></item>
5127 The `xterm' terminfo entry should have <tt>ESC [ 3
5128 ~</tt> for kdch1, just like TERM=linux and
5129 TERM=vt220.</p></item>
5132 Emacs is programmed to map KB_Backspace or the `stty
5133 erase' character to delete-backward-char, and
5134 KB_Delete or kdch1 to delete-forward-char, and
5135 <tt>^H</tt> to help as always.</p></item>
5138 Other applications use the `stty erase' character and
5139 kdch1 for the two delete keys, with ASCII DEL being
5140 `delete previous character' and kdch1 being `delete
5141 character under cursor'.</p></item>
5145 This will solve the problem except for:</p>
5150 Some terminals have a <tt><--</tt> key that cannot
5151 be made to produce anything except <tt>^H</tt>. On
5152 these terminals Emacs help will be unavailable on
5153 <tt>^H</tt> (assuming that the `stty erase' character
5154 takes precedence in Emacs, and has been set
5155 correctly). M-x help or F1 (if available) can be used
5159 Some operating systems use <tt>^H</tt> for stty erase.
5160 However, modern telnet versions and all rlogin
5161 versions propagate stty settings, and almost all UNIX
5162 versions honour stty erase. Where the stty settings
5163 are not propagated correctly things can be made to
5164 work by using stty manually.</p></item>
5167 Some systems (including previous Debian versions) use
5168 xmodmap to arrange for both <tt><--</tt> and Delete
5169 to generate KB_Delete. We can change the behavior
5170 of their X clients via the same X resources that we
5171 use to do it for our own, or have our clients be
5172 configured via their resources when things are the
5173 other way around. On displays configured like this
5174 Delete will not work, but <tt><--</tt>
5178 Some operating systems have different kdch1 settings
5179 in their terminfo for xterm and others. On these
5180 systems the Delete key will not work correctly when
5181 you log in from a system conforming to our policy, but
5182 <tt><--</tt> will.</p></item>
5189 <heading>Environment variables</heading>
5192 A program must not depend on environment variables to get
5193 reasonable defaults. (That's because these environment
5194 variables would have to be set in a system-wide
5195 configuration file like /etc/profile, which is not supported
5199 If a program usually depends on environment variables for its
5200 configuration, the program should be changed to fall back to
5201 a reasonable default configuration if these environment
5202 variables are not present. If this cannot be done easily
5203 (e.g., if the source code of a non-free program is not
5204 available), the program must be replaced by a small
5205 `wrapper' shell script which sets the environment variables
5206 if they are not already defined, and calls the original program.</p>
5209 Here is an example of a wrapper script for this purpose:
5211 <example compact="compact">
5213 BAR=${BAR:-/var/lib/fubar}
5215 exec /usr/lib/foo/foo "$@"
5219 Furthermore, as <tt>/etc/profile</tt> is a configuration
5220 file of the <prgn>base-files</prgn> package, other packages must not
5221 put any environment variables or other commands into that
5226 <heading>Files</heading>
5230 <heading>Binaries</heading>
5233 Two different packages must not install programs with
5234 different functionality but with the same filenames. (The
5235 case of two programs having the same functionality but
5236 different implementations is handled via `alternatives.')
5237 If this case happens, one of the programs must be
5238 renamed. The maintainers should report this to the
5239 developers' mailing and try to find a consensus about
5240 which package will have to be renamed. If a consensus can
5241 not be reached, <em>both</em> programs must be
5245 Generally the following compilation parameters should be used:
5246 <example compact="compact">
5248 CFLAGS = -O2 -Wall # sane warning options vary between programs
5250 install -s # (or use strip on the files in debian/tmp)
5254 Note that by default all installed binaries should be stripped,
5255 either by using the <tt>-s</tt> flag to
5256 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5257 the binaries after they have been copied into
5258 <tt>debian/tmp</tt> but before the tree is made into a
5262 The <tt>-N</tt> flag should not be used. On a.out systems
5263 it may have been useful for some very small binaries, but
5264 for ELF it has no good effect.</p>
5267 Debugging symbols are useful for error diagnosis,
5268 investigation of core dumps (which may be submitted by users
5269 in bug reports), or testing and developing the
5270 software. Therefore it is recommended to support building
5271 the package with debugging information through the following
5272 interface: If the environment variable
5273 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5274 <tt>debug</tt>, compile the software with debugging
5275 information (usually this involves adding the <tt>-g</tt>
5276 flag to <tt>CFLAGS</tt>). This allows the generation of a
5277 build tree with debugging information. If the environment
5278 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5279 <tt>nostrip</tt>, do not strip the files at installation
5280 time. This allows one to generate a package with debugging
5281 information included. The following makefile snippet is only
5282 an example of how one may test for either condition:
5285 Rationale: Building by default with -g causes more
5286 wasted CPU cycles since the information is stripped away
5287 anyway. The package can by default build without -g if
5288 it also provides a mechanism to easily be rebuilt with
5289 debugging information. This can be done by providing a
5290 "build-debug" make target, or allowing the user to
5291 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5292 compiling that package.
5294 <p>Now this has several added benefits:
5295 <list compact="compact">
5298 It is actually easier to build debugging bins and
5299 libraries this way (no more editing debian/rules
5300 or similar) since it provides a documented way of
5301 getting this type of build.</p>
5305 There will be much less wasted CPU time for the
5306 autobuilders since not having debugging
5307 information (and hence also not having to strip
5308 it) will increase the speed of compiles. This
5309 skips an entire pass of the compiler.
5317 <example compact="compact">
5320 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5321 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5322 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5323 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5325 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5328 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5329 INSTALL_PROGRAM += -s
5333 Please note that the above example is merely informative,
5334 and is not a policy mandate. You may have to massage this
5335 example in order to make it work for your package.
5340 It is up to the package maintainer to decide what
5341 compilation options are best for the package. Certain
5342 binaries (such as computationally-intensive programs) will
5343 function better with certain flags (<tt>-O3</tt>, for
5344 example); feel free to use them. Please use good judgment
5345 here. Don't use flags for the sake of it; only use them
5346 if there is good reason to do so. Feel free to override
5347 the upstream author's ideas about which compilation
5348 options are best: they are often inappropriate for our
5349 environment.</p></sect>
5353 <heading>Libraries</heading>
5356 All libraries must have a shared version in the lib
5357 package and a static version in the lib-dev package. The
5358 shared version must be compiled with <tt>-fPIC</tt>, and
5359 the static version must not be. In other words, each
5360 <tt>*.c</tt> file will need to be compiled twice.</p>
5363 You must specify the gcc option <tt>-D_REENTRANT</tt>
5364 when building a library (either static or shared) to make
5365 the library compatible with LinuxThreads.</p>
5368 Note that all installed shared libraries should be
5370 <example compact="compact">
5371 strip --strip-unneeded <your-lib>
5373 (The option <tt>--strip-unneeded</tt> makes
5374 <prgn>strip</prgn> remove only the symbols which aren't
5375 needed for relocation processing.) Shared libraries can
5376 function perfectly well when stripped, since the symbols for
5377 dynamic linking are in a separate part of the ELF object
5381 Note that under some circumstances it may be useful to
5382 install a shared library unstripped, for example when
5383 building a separate package to support debugging.
5387 An ever increasing number of packages are using libtool to
5388 do their linking. The latest GNU libtools (>= 1.3a) can take
5389 advantage of the metadata in the installed libtool archive
5390 files (`*.la'). The main advantage of libtool's .la files is
5391 that it allows libtool to store and subsequently access
5392 metadata with respect to the libraries it builds. libtool
5393 will search for those files, which contain a lot of useful
5394 information about a library (e.g. dependency libraries for
5395 static linking). Also, they're <em>essential</em> for
5396 programs using libltdl.
5400 Certainly libtool is fully capable of linking against shared
5401 libraries which don't have .la files, but being a mere shell
5402 script it can add considerably to the build time of a
5403 libtool using package if that shell-script has to derive all
5404 this information from first principles for each library every
5405 time it is linked. With the advent of libtool-1.4 (and to a
5406 lesser extent libtool-1.3), the .la files will also store
5407 information about inter-library dependencies which cannot
5408 necessarily be derived after the .la file is deleted.
5412 Packages that use libtool to create shared libraries should
5413 include the <em>.la</em> files in the <em>-dev</em>
5414 packages, with the exception that if the package relies on
5415 libtool's <em>libltdl</em> library, in which case the .la
5416 files must go in the run-time library package. This is a
5417 good idea in general, and especially for static linking
5422 You must make sure that you use only released versions of
5423 shared libraries to build your packages; otherwise other
5424 users will not be able to run your binaries
5425 properly. Producing source packages that depend on
5426 unreleased compilers is also usually a bad
5433 <heading>Shared libraries</heading>
5436 Packages involving shared libraries should be split up
5437 into several binary packages.</p>
5440 For a straightforward library which has a development
5441 environment and a runtime kit including just shared
5442 libraries you need to create two packages:
5443 <tt><var>libraryname</var><var>soname</var></tt>
5444 (<var>soname</var> is the shared object name of the shared
5445 library: it's the thing that has to match exactly between
5446 building an executable and running it for the dynamic
5447 linker to be able run the program; usually the
5448 <var>soname</var> is the major number of the library) and
5449 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5452 If you prefer only to support one development version at a
5453 time you may name the development package
5454 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5455 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5456 ensure that the user only installs one development version
5457 at a time (after all, different development versions are
5458 likely to have the same header files in them, causing a
5459 filename clash if both are installed). Typically the
5460 development version should also have an exact version
5461 dependency on the runtime library, to make sure that
5462 compilation and linking happens correctly.</p>
5465 Packages which use the shared library should have a
5466 dependency on the name of the shared library package,
5467 <tt><var>libraryname</var><var>soname</var></tt>. When
5468 the <var>soname</var> changes you can have both versions
5469 of the library installed while moving from the old library
5473 If your package has some run-time support programs which
5474 use the shared library you must not put them in
5475 the shared library package. If you do that then you won't
5476 be able to install several versions of the shared library
5477 without getting filename clashes. Instead, either create
5478 a third package for the runtime binaries (this package
5479 might typically be named
5480 <tt><var>libraryname</var>-runtime</tt>; note the absence
5481 of the <var>soname</var> in the package name) or if the
5482 development package is small include them in there.</p>
5485 If you have several shared libraries built from the same
5486 source tree you may lump them all together into a single
5487 shared library package, provided that you change all their
5488 <var>soname</var>s at once (so that you don't get filename
5489 clashes if you try to install different versions of the
5490 combined shared libraries package).</p>
5493 You should follow the directions in the <em>Debian Packaging
5494 Manual</em> (or other documentation of the Debian
5495 packaging tools) for putting the shared library in its
5496 package, and you must include a <tt>shlibs</tt> control area
5497 file with details of the dependencies for packages which use
5501 Shared libraries should not be installed
5502 executable, since <prgn>ld.so</prgn> does not require this
5503 and trying to execute a shared library results in a core
5508 <heading>Scripts</heading>
5511 All command scripts, including the package maintainer
5512 scripts inside the package and used by <prgn>dpkg</prgn>,
5513 should have a <tt>#!</tt> line naming the shell to be used
5514 to interpret them.</p>
5517 In the case of Perl scripts this should be
5518 <tt>#!/usr/bin/perl</tt>.</p>
5521 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5522 should almost certainly start with <tt>set -e</tt> so that
5523 errors are detected. Every script should use
5524 <tt>set -e</tt> or check the exit status of <em>every</em>
5528 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5529 symbolic link to any POSIX compatible shell, if <tt>echo
5530 -n</tt> does not generate a newline.
5533 Debian policy specifies POSIX behavior for /bin/sh, but
5534 echo -n has widespread use in the Linux community
5535 (including especially debian policy, the linux kernel
5536 source, many debian scripts, etc.). This echo -n
5537 mechanism is valid but not required under POSIX, hence
5538 this explicit addition. Also, rumour has it that this
5539 shall be mandated under the LSB anyway.
5543 specifying `<tt>/bin/sh</tt>' as interpreter should only
5544 use POSIX features. If a script requires non-POSIX
5545 features from the shell interpreter, the appropriate shell
5546 must be specified in the first line of the script (e.g.,
5547 `<tt>#!/bin/bash</tt>') and the package must depend on the
5548 package providing the shell (unless the shell package is
5549 marked `Essential', e.g., in the case of
5554 You may wish to restrict your script to POSIX features when possible so
5555 that it may use <tt>/bin/sh</tt> as its interpreter. If
5556 your script works with <prgn>ash</prgn>, it's probably
5557 POSIX compliant, but if you are in doubt, use
5558 <tt>/bin/bash</tt>.</p>
5561 Perl scripts should check for errors when making any
5562 system calls, including <tt>open</tt>, <tt>print</tt>,
5563 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5566 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5567 as scripting languages. See <em>Csh Programming
5568 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5569 FAQs. It can be found on
5570 <url id="http://language.perl.com/versus/csh.whynot">, or
5571 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5572 or even on <ftpsite>ftp.cpan.org</ftpsite>
5573 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5574 If an upstream package comes with <prgn>csh</prgn> scripts
5575 then you must make sure that they start with
5576 <tt>#!/bin/csh</tt> and make your package depend on the
5577 <prgn>c-shell</prgn> virtual package.</p>
5580 Any scripts which create files in world-writeable
5581 directories (e.g., in <tt>/tmp</tt>) must use a
5582 mechanism which will fail if a file with the same name
5586 The Debian base distribution provides the
5587 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5588 for use by scripts for this purpose.</p></sect>
5592 <heading>Symbolic links</heading>
5595 In general, symbolic links within a top-level directory
5596 should be relative, and symbolic links pointing from one
5597 top-level directory into another should be absolute. (A
5598 top-level directory is a sub-directory of the root
5602 In addition, symbolic links should be specified as short
5603 as possible, i.e., link targets like `foo/../bar' are
5607 Note that when creating a relative link using
5608 <prgn>ln</prgn> it is not necessary for the target of the
5609 link to exist relative to the working directory you're
5610 running <prgn>ln</prgn> from; nor is it necessary to
5611 change directory to the directory where the link is to be
5612 made. Simply include the string that should appear as the
5613 target of the link (this will be a pathname relative to
5614 the directory in which the link resides) as the first
5615 argument to <prgn>ln</prgn>.</p>
5618 For example, in your <prgn>Makefile</prgn> or
5619 <tt>debian/rules</tt>, do things like:
5620 <example compact="compact">
5621 ln -fs gcc $(prefix)/bin/cc
5622 ln -fs gcc debian/tmp/usr/bin/cc
5623 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5624 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5628 A symbolic link pointing to a compressed file should
5629 always have the same file extension as the referenced
5630 file. (For example, if a file `<tt>foo.gz</tt>' is
5631 referenced by a symbolic link, the filename of the link
5632 has to end with `<tt>.gz</tt>' too, as in
5633 `bar.gz.')</p></sect>
5637 <heading>Device files</heading>
5640 Packages must not include device files in the package file
5644 If a package needs any special device files that are not
5645 included in the base system, it must call
5646 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5647 after asking the user for permission to do so.</p>
5650 Packages must not remove any device files in the
5651 <tt>postrm</tt> or any other script. This is left to the
5652 system administrator.</p>
5655 Debian uses the serial devices
5656 <tt>/dev/ttyS*</tt>. Programs using the old
5657 <tt>/dev/cu*</tt> devices should be changed to use
5658 <tt>/dev/ttyS*</tt>.</p>
5661 <sect id="config files">
5662 <heading>Configuration files</heading>
5664 <heading>Definitions</heading>
5667 <tag>configuration file</tag>
5669 A file that affects the operation of program, or
5670 provides site- or host-specific information, or
5671 otherwise customizes the behavior of program.
5672 Typically, configuration files are intended to be
5673 modified by the system administrator (if needed or
5674 desired) to conform to local policy or provide more
5675 useful site-specific behavior.</p>
5678 <tag><tt>conffile</tt></tag>
5680 A file listed in a package's <tt>conffiles</tt>
5681 file, and is treated specially by <prgn>dpkg</prgn>
5682 (see the <em>Debian Packaging Manual</em>).</p>
5688 The distinction between these two is important; they are
5689 not interchangeable concepts. Almost all
5690 <tt>conffiles</tt> are configuration files, but many
5691 configuration files are not <tt>conffiles</tt>.</p>
5694 Note that a script that embeds configuration information
5695 (such as most of the files in <tt>/etc/init.d</tt> and
5696 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5697 configuration file and should be treated as such.</p>
5701 <heading>Location</heading>
5703 Any configuration files created or used by your package
5704 must reside in <tt>/etc</tt>. If there are several you
5705 should consider creating a subdirectory of <tt>/etc</tt>
5706 named after your package.</p>
5709 If your package creates or uses configuration files
5710 outside of <tt>/etc</tt>, and it is not feasible to modify
5711 the package to use the <tt>/etc</tt>, you should still put
5712 the files in <tt>/etc</tt> and create symbolic links to
5713 those files from the location that the package
5718 <heading>Behavior</heading>
5720 Configuration file handling must conform to the following
5722 <list compact="compact">
5724 <p>local changes must be preserved during a package
5728 <p>configuration files must be preserved when the
5729 package is removed, and only deleted when the
5730 package is purged.</p>
5735 The easy way to achieve this behavior is to make the
5736 configuration file a <tt>conffile</tt>. This is
5737 appropriate only if it is possible to distribute a default
5738 version that will work for most installations, although
5739 some system administrators may choose to modify it. This
5740 implies that the default version will be part of the
5741 package distribution, and must not be modified by the
5742 maintainer scripts during installation (or at any other
5747 In order to ensure that local changes are preserved
5748 correctly, no package may contain or make hard links to
5752 Rationale: There are two problems with hard links.
5753 The first is that some editors break the link while
5754 editing one of the files, so that the two files may
5755 unwittingly become different. The second is that
5756 <prgn>dpkg</prgn> might break the hard link while
5757 upgrading <tt>conffile</tt>s.
5763 The other way to do it is via the maintainer scripts.
5764 In this case, the configuration file must not be listed as
5765 a <tt>conffile</tt> and must not be part of the package
5766 distribution. If the existence of a file is required for
5767 the package to be sensibly configured it is the
5768 responsibility of the package maintainer to write scripts
5769 which correctly create, update, maintain and
5770 remove-on-purge the file. These scripts must be idempotent
5771 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5772 re-run them due to errors during installation or removal),
5773 must cope with all the variety of ways <prgn>dpkg</prgn>
5774 can call maintainer scripts, must not overwrite or
5775 otherwise mangle the user's configuration without asking,
5776 must not ask unnecessary questions (particularly during
5777 upgrades), and otherwise be good citizens.</p>
5780 The scripts are not required to configure every possible option for
5781 the package, but only those necessary to get the package
5782 running on a given system. Ideally the sysadmin should not
5783 have to do any configuration other than that done
5784 (semi-)automatically by the <tt>postinst</tt> script.</p>
5787 A common practice is to create a script called
5788 <tt><var>package</var>-configure</tt> and have the
5789 package's <tt>postinst</tt> call it if and only if the
5790 configuration file does not already exist. In certain
5791 cases it is useful for there to be an example or template
5792 file which the maintainer scripts use. Such files should
5793 be in <tt>/usr/share/<package></tt> or
5794 <tt>/usr/lib/<package></tt> with a symbolic link
5795 from <tt>/usr/share/doc/<package>/examples</tt>
5796 if they are examples, and should be
5797 perfectly ordinary <prgn>dpkg</prgn>-handled files
5798 (<em>not</em> <tt>conffiles</tt>).
5802 These two styles of configuration file handling must
5803 not be mixed, for that way lies madness:
5804 <prgn>dpkg</prgn> will ask about overwriting the file
5805 every time the package is upgraded.</p>
5810 <heading>Sharing configuration files</heading>
5812 Packages which specify the same file as
5813 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5818 The maintainer scripts must not alter the conffile of
5819 <em>any</em> package, including the one the scripts belong
5823 If two or more packages use the same configuration file
5824 and it is reasonable for both to be installed at the same
5825 time, one of these packages must be defined as
5826 <em>owner</em> of the configuration file, i.e., it will be
5827 the package to list that distributes the file and lists it
5828 as a <tt>conffile</tt>. Other packages that use the
5829 configuration file must depend on the owning package if
5830 they require the configuration file to operate. If the
5831 other package will use the configuration file if present,
5832 but is capable of operating without it, no dependency need
5836 If it is desirable for two or more related packages to
5837 share a configuration file <em>and</em> for all of the
5838 related packages to be able to modify that configuration
5839 file, then the following should be done:
5843 have one of the related packages (the "core"
5844 package) manage the configuration file with
5845 maintainer scripts as described in the previous
5849 the core package should also provide a program that
5850 the other packages may use to modify the
5851 configuration file.</p>
5855 the related packages must use the provided program
5856 to make any modifications to the configuration file.
5857 They should either depend on the core package to
5858 guarantee that the configuration modifier program is
5859 available or accept gracefully that they cannot
5860 modify the configuration file if it is not.</p>
5865 Sometimes it's appropriate to create a new package which
5866 provides the basic infrastructure for the other packages
5867 and which manages the shared configuration files. (Check
5868 out the <tt>sgml-base</tt> package as an example.)</p>
5872 <heading>User configuration files ("dotfiles")</heading>
5875 Files in <tt>/etc/skel</tt> will automatically be copied
5876 into new user accounts by <prgn>adduser</prgn>. They
5877 should not be referenced there by any program.</p>
5880 Therefore, if a program needs a dotfile to exist in
5881 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5882 should be installed in <tt>/etc/skel</tt> (and listed in
5883 conffiles, if it is not generated and modified dynamically
5884 by the package's installation scripts).</p>
5887 However, programs that require dotfiles in order to
5888 operate sensibly (dotfiles that they do not create
5889 themselves automatically, that is) are a bad thing, and
5890 programs should be configured by the Debian default
5891 installation as close to normal as possible.</p>
5894 Therefore, if a program in a Debian package needs to be
5895 configured in some way in order to operate sensibly that
5896 configuration should be done in a site-wide global
5897 configuration file elsewhere in <tt>/etc</tt>. Only if the
5898 program doesn't support a site-wide default configuration
5899 and the package maintainer doesn't have time to add it
5900 may a default per-user file be placed in
5901 <tt>/etc/skel</tt>.</p>
5904 <tt>/etc/skel</tt> should be as empty as we can make it.
5905 This is particularly true because there is no easy
5906 mechanism for ensuring that the appropriate dotfiles are
5907 copied into the accounts of existing users when a package
5913 <heading>Log files</heading>
5915 The traditional approach to log files has been to set up ad
5916 hoc log rotation schemes using simple shell scripts and
5917 cron. While this approach is highly customizable, it
5918 requires quite a lot of sysadmin work. Even though the
5919 original Debian system helped a little by automatically
5920 installing a system which can be used as a template, this
5921 was deemed not enough.
5925 A better scheme is to use logrotate, a GPL'd program
5926 developed by Red Hat, which centralizes log management. It
5927 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5928 and a directory where packages can drop logrotation info
5929 (<tt>/etc/logrotate.d</tt>).
5933 Log files should usually be named
5934 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5935 log files, or need a separate directory for permissions
5936 reasons (<tt>/var/log</tt> is writable only by
5937 <tt>root</tt>), you should usually create a directory named
5938 <tt>/var/log/<var>package</var></tt>.</p>
5941 Log files must be rotated occasionally so
5942 that they don't grow indefinitely; the best way to do this
5943 is to drop a script into the directory
5944 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5945 logrotate. Here is a good example for a logrotate config
5946 file (for more information see <manref name="logrotate"
5948 <example compact="compact">
5954 /etc/init.d/foo force-reload
5958 Which rotates all files under `/var/log/foo', saves 12
5959 compressed generations, and sends a HUP signal at the end of
5965 Log files should be removed when the package is
5966 purged (but not when it is only removed), by checking the
5967 argument to the <tt>postrm</tt> script (see the <em>Debian
5968 Packaging Manual</em> for details).</p>
5973 <heading>Permissions and owners</heading>
5976 The rules in this section are guidelines for general use.
5977 If necessary you may deviate from the details below.
5978 However, if you do so you must make sure that what is done
5979 is secure and you should try to be as consistent as possible
5980 with the rest of the system. You should probably also
5981 discuss it on <prgn>debian-devel</prgn> first.</p>
5984 Files should be owned by <tt>root.root</tt>, and made
5985 writable only by the owner and universally readable (and
5986 executable, if appropriate).</p>
5989 Directories should be mode 755 or (for group-writability)
5990 mode 2775. The ownership of the directory should be
5991 consistent with its mode: if a directory is mode 2775, it
5992 should be owned by the group that needs write access to
5996 Setuid and setgid executables should be mode 4755 or 2755
5997 respectively, and owned by the appropriate user or group.
5998 They should not be made unreadable (modes like 4711 or
5999 2711 or even 4111); doing so achieves no extra security,
6000 because anyone can find the binary in the freely available
6001 Debian package, it is merely inconvenient. For the same
6002 reason you should not restrict read or execute permissions
6003 on non-set-id executables.</p>
6006 Some setuid programs need to be restricted to particular
6007 sets of users, using file permissions. In this case they
6008 should be owned by the uid to which they are set-id, and
6009 by the group which should be allowed to execute them.
6010 They should have mode 4754; there is no point in making
6011 them unreadable to those users who must not be allowed to
6015 You must not arrange that the system administrator can only
6016 reconfigure the package to correspond to their local
6017 security policy by changing the permissions on a binary.
6018 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
6019 to conffiles and other similar objects) have their
6020 permissions reset to the distributed permissions when the
6021 package is reinstalled. Instead you should consider (for
6022 example) creating a group for people allowed to use the
6023 program(s) and making any setuid executables executable
6024 only by that group.</p>
6027 If you need to create a new user or group for your package
6028 there are two possibilities. Firstly, you may need to
6029 make some files in the binary package be owned by this
6030 user or group, or you may need to compile the user or
6031 group id (rather than just the name) into the binary
6032 (though this latter should be avoided if possible, as in
6033 this case you need a statically allocated id).</p>
6036 If you need a statically allocated id, you must ask for a
6037 user or group id from the base system
6038 maintainer, and must not release the package until you
6039 have been allocated one. Once you have been allocated one
6040 you must make the package depend on a version of the base
6041 system with the id present in <tt>/etc/passwd</tt> or
6042 <tt>/etc/group</tt>, or alternatively arrange for your
6043 package to create the user or group itself with the
6044 correct id (using <tt>adduser</tt>) in its pre- or
6045 post-installation script (the latter is to be preferred if
6046 it is possible).</p>
6049 On the other hand, the program might be able to determine the
6050 uid or gid from the group name at runtime, so that a
6051 dynamic id can be used. In this case you should choose an
6052 appropriate user or group name, discussing this on
6053 <prgn>debian-devel</prgn> and checking with the base
6054 system maintainer that it is unique and that they do not
6055 wish you to use a statically allocated id instead. When
6056 this has been checked you must arrange for your package to
6057 create the user or group if necessary using
6058 <prgn>adduser</prgn> in the pre- or post-installation
6059 script (again, the latter is to be preferred if it is
6063 Note that changing the numeric value of an id associated with a name
6064 is very difficult, and involves searching the file system for all
6065 appropriate files. You need to think carefully whether a static or
6066 dynamic id is required, since changing your mind later will cause
6071 <chapt id="customized-programs">
6072 <heading>Customized programs</heading>
6074 <sect id="arch-spec">
6075 <heading>Architecture specification strings</heading>
6078 If a program needs to specify an <em>architecture specification
6079 string</em> in some place, the following format should be used:
6080 <example compact="compact">
6081 <arch>-<os>
6083 where `<arch>' is one of the following: i386, alpha, arm, m68k,
6084 powerpc, sparc and `<os>' is one of: linux, gnu. Use
6085 of <em>gnu</em> in this string is reserved for the GNU/Hurd
6086 operating system.</p>
6088 Note, that we don't want to use `<arch>-debian-linux'
6089 to apply to the rule `architecture-vendor-os' since this
6090 would make our programs incompatible to other Linux
6091 distributions. Also note, that we don't use
6092 `<arch>-unknown-linux', since the `unknown' does not
6093 look very good.</p></sect>
6097 <heading>Daemons</heading>
6100 The configuration files <tt>/etc/services</tt>,
6101 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6102 by the <prgn>netbase</prgn> package and may not be modified
6103 by other packages.</p>
6106 If a package requires a new entry in one of these files, the
6107 maintainer should get in contact with the
6108 <prgn>netbase</prgn> maintainer, who will add the entries
6109 and release a new version of the <prgn>netbase</prgn>
6113 The configuration file <tt>/etc/inetd.conf</tt> must not be
6114 modified by the package's scripts except via the
6115 <prgn>update-inetd</prgn> script or the
6116 <prgn>DebianNet.pm</prgn> Perl module.</p>
6119 If a package wants to install an example entry into
6120 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6121 exactly one hash character (<tt>#</tt>). Such lines are
6122 treated as `commented out by user' by the
6123 <prgn>update-inetd</prgn> script and are not changed or
6124 activated during a package updates.</p></sect>
6128 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
6131 Some programs need to create pseudo-ttys. This should be done
6132 using Unix98 ptys if the C library supports it. The resulting
6133 program must not be installed setuid root, unless that
6134 is required for other functionality.
6138 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6139 <tt>/var/log/lastlog</tt> must be installed writeable by
6140 group utmp. Programs who need to modify those files must
6141 be installed setgid utmp.
6146 <heading>Editors and pagers</heading>
6149 Some programs have the ability to launch an editor or pager
6150 program to edit or display a text document. Since there are
6151 lots of different editors and pagers available in the Debian
6152 distribution, the system administrator and each user should
6153 have the possibility to choose his/her preferred editor and
6157 In addition, every program should choose a good default
6158 editor/pager if none is selected by the user or system
6162 Thus, every program that launches an editor or pager must
6163 use the EDITOR or PAGER environment variables to determine
6164 the editor/pager the user wants to get started. If these
6165 variables are not set, the programs <tt>/usr/bin/editor</tt>
6166 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
6169 These two files are managed through `alternatives.' That is,
6170 every package providing an editor or pager must call the
6171 <prgn>update-alternatives</prgn> script to register these
6175 If it is very hard to adapt a program to make us of the
6176 EDITOR and PAGER variables, that program may be configured
6177 to use <tt>/usr/bin/sensible-editor</tt> and
6178 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
6179 respectively. These are two scripts provided in the Debian
6180 base system that check the EDITOR and PAGER variables and
6181 launch the appropriate program or fall back to
6182 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
6186 A program may also use the VISUAL environment variable to
6187 determine the user's choice of editor. If it exists, it
6188 should take precedence over EDITOR. This is in fact what
6189 <tt>/usr/bin/sensible-editor</tt> does.</p>
6192 It is not required for a package to depend on
6193 `editor' and `pager', nor is it required for a package to
6194 provide such virtual packages.
6197 The Debian base system already provides an editor and
6206 <sect id="web-appl">
6207 <heading>Web servers and applications</heading>
6210 This section describes the locations and URLs that should
6211 be used by all web servers and web application in the Debian
6217 <p>Cgi-bin executable files are installed in the
6219 <example compact="compact">
6220 /usr/lib/cgi-bin/<cgi-bin-name>
6222 and should be referred to as
6223 <example compact="compact">
6224 http://localhost/cgi-bin/<cgi-bin-name>
6229 <item><p>Access to html documents</p>
6232 Html documents for a package are stored in
6233 <tt>/usr/share/doc/<var>package</var></tt> but should
6234 be accessed via symlinks as
6235 <tt>/usr/doc/<var>package</var></tt><footnote> for
6236 backward compatibility, see <ref id="usrdoc"></footnote>
6237 and can be referred to as
6238 <example compact="compact">
6239 http://localhost/doc/<package>/<filename>
6244 <item><p>Web Document Root</p>
6247 Web Applications should try to avoid storing files in
6248 the Web Document Root. Instead they should use the
6249 /usr/share/doc/<package> directory for documents and
6250 register the Web Application via the menu package. If
6251 access to the web-root is unavoidable then use
6252 <example compact="compact">
6255 as the Document Root. This might be just a
6256 symbolic link to the location where the sysadmin has
6257 put the real document root.</p>
6260 </enumlist></p></sect>
6263 <sect id="mail-transport-agents">
6264 <heading>Mail transport, delivery and user agents</heading>
6267 Debian packages which process electronic mail, whether
6268 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6269 must make sure that they are compatible with the
6270 configuration decisions below. Failure to do this may
6271 result in lost mail, broken <tt>From:</tt> lines, and other
6272 serious brain damage!</p>
6275 The mail spool is <tt>/var/mail</tt> and the interface
6276 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6277 per the FHS). On older systems, the mail spool may be
6278 physically located in /var/spool/mail, but all access to the
6279 mail spool should be via the /var/mail symlink. The mail
6280 spool is part of the base system and not part of the MTA
6285 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6286 programs (like IMAP daemons) must lock the mailbox in an
6287 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6288 be combined with dot locking. To avoid deadlocks, a
6289 program should use <tt>fcntl()</tt> first and dot locking
6290 after this or alternatively implement the two locking
6291 methods in a non blocking way<footnote>
6293 If it is not possible to establish both locks, the
6294 system shouldn't wait for the second lock to be
6295 established, but remove the first lock, wait a (random)
6296 time, and start over locking again.</p>
6297 </footnote>. Using the functions <tt>maillock</tt> and
6298 <tt>mailunlock</tt> provided by the
6299 <tt>liblockfile*</tt><footnote>
6301 <tt>liblockfile</tt> version >>1.01</p>
6302 </footnote> packages is the recommended way to realize this.
6306 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6307 unless the user has chosen otherwise. A MUA may remove a
6308 mailbox (unless it has nonstandard permissions) in which
6309 case the MTA or another MUA must recreate it if needed.
6310 Mailboxes must be writable by group mail.</p>
6313 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6314 be setgid mail to do the locking mentioned above (and
6315 must obviously avoid accessing other users' mailboxes
6316 using this privilege).</p>
6319 <tt>/etc/aliases</tt> is the source file for the system mail
6320 aliases (e.g., postmaster, usenet, etc.), it is the one
6321 which the sysadmin and <tt>postinst</tt> scripts may edit.
6322 After <tt>/etc/aliases</tt> is edited the program or human
6323 editing it must call <prgn>newaliases</prgn>. All MTA
6324 packages must come with a <prgn>newaliases</prgn> program,
6325 even if it does nothing, but older MTA packages do not do
6326 this so programs should not fail if <prgn>newaliases</prgn>
6327 cannot be found.</p>
6330 The convention of writing <tt>forward to
6331 <var>address</var></tt> in the mailbox itself is not
6332 supported. Use a <tt>.forward</tt> file instead.</p>
6335 The <prgn>rmail</prgn> program used by UUCP
6336 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6337 Likewise, <prgn>rsmtp</prgn>, for receiving
6338 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6342 If you need to know what name to use (for example) on
6343 outgoing news and mail messages which are generated locally,
6344 you should use the file <tt>/etc/mailname</tt>. It will
6345 contain the portion after the username and <tt>@</tt> (at)
6346 sign for email addresses of users on the machine (followed
6350 A package should check for the existence of this file. If
6351 it exists it should use it without comment. (An MTA's
6352 prompting configuration script may wish to prompt the user
6353 even if it finds this file exists.) If it does not exist it
6354 should prompt the user for the value and store it in
6355 <tt>/etc/mailname</tt> as well as using it in the package's
6356 configuration. The prompt should make it clear that the
6357 name will not just be used by that package. For example, in
6358 this situation the INN package says:
6359 <example compact="compact">
6360 Please enter the `mail name' of your system. This is the
6361 hostname portion of the address to be shown on outgoing
6362 news and mail messages. The default is
6363 <var>syshostname</var>, your system's host name. Mail
6364 name [`<var>syshostname</var>']:
6366 where <var>syshostname</var> is the output of <tt>hostname
6372 <heading>News system configuration</heading>
6375 All the configuration files related to the NNTP (news)
6376 servers and clients should be located under
6377 <tt>/etc/news</tt>.</p>
6380 There are some configuration issues that apply to a number
6381 of news clients and server packages on the machine. These
6385 <tag>/etc/news/organization</tag>
6386 <item><p>A string which should appear as the
6387 organization header for all messages posted
6388 by NNTP clients on the machine</p></item>
6390 <tag>/etc/news/server</tag>
6391 <item><p>Contains the FQDN of the upstream NNTP
6392 server, or localhost if the local machine is
6393 an NNTP server.</p></item>
6396 Other global files may be added as required for cross-package news
6397 configuration.</p></sect>
6401 <heading>Programs for the X Window System</heading>
6404 <em>Programs that may be configured with support for the X Window
6405 System</em> must be configured to do so and must declare any
6406 package dependencies necessary to satisfy their runtime
6407 requirements when using the X Window System, unless the package
6408 in question is of standard or higher priority, in which case
6409 X-specific binaries may be split into a separate package, or
6410 alternative versions of the package with X support may be
6416 <em>Packages which provide an X server</em> that, directly or
6417 indirectly, communicates with real input and display hardware
6418 should declare in their control data that they provide the
6419 virtual package <tt>xserver</tt>.
6422 This implements current practice, and provides an actual
6423 policy for usage of the "xserver" virtual package which
6424 appears in the virtual packages list. In a nutshell, X
6425 servers that interface directly with the display and input
6426 hardware or via another subsystem (e.g., GGI) should provide
6427 xserver. Things like Xvfb, Xnest, and Xprt should not.
6433 <em>Packages that provide a terminal emulator</em> for the X
6434 Window System which support a terminal type with a terminfo
6435 description provided in the <tt>ncurses-base</tt> package
6436 should declare in their control data that they provide the
6437 virtual package <tt>x-terminal-emulator</tt>. They should
6438 also register themselves as an alternative for
6439 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6444 <em>Packages that provide window managers</em> should declare in
6445 their control data that they provide the virtual package
6446 <tt>x-window-manager</tt>. They should also register themselves as an
6447 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6448 calculated as follows:
6449 <list compact="compact">
6450 <item>Start with a priority of 20.</item>
6451 <item>If the window manager supports the Debian menu system,
6452 add 20 points if this support is available in the
6453 package's default configuration (i.e., no
6454 configuration files belonging to the system or user
6455 have to be edited to activate the feature); if
6456 configuration files must be modified, add only 10
6458 <item>If the window manager permits the X session to be
6459 restarted using a <em>different</em> window manager
6460 (without killing the X server) in its default
6461 configuration, add 10 points; otherwise add
6467 <em>Packages that provide fonts for the X Window System</em>
6468 must do a number of things to ensure that they are both
6469 available without modification of the X or font server
6470 configuration, and that they do not corrupt files used by
6471 other font packages to register information about themselves.
6474 Fonts of any type supported by the X Window System
6475 should be be in a separate binary package from any
6476 executables, libraries, or documentation (except that
6477 specific to the fonts shipped); if a program or
6478 library is <em>unusable</em> without one or more
6479 specific fonts, the package containing the program or
6480 library should declare a dependency on the package(s)
6481 containing the font(s) it requires.
6484 BDF fonts should be converted to PCF fonts with the
6485 <tt>bdftopcf</tt> utility (available in the
6486 <tt>xutils</tt> package), <tt>gzip</tt>ped, and
6487 placed in a directory that corresponds to their
6489 <list compact="compact">
6491 100 dpi fonts should be placed in
6492 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6495 75 dpi fonts should be placed in
6496 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6499 Character-cell fonts, cursor fonts, and other
6500 low-resolution fonts should be placed in
6501 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6506 Speedo fonts should be placed in
6507 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6510 Type 1 fonts should be placed in
6511 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6512 metric files are available, they may be placed here as
6516 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6517 other than those listed above should be neither created nor
6518 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6519 excepted for historical reasons, but installation of files into
6520 these directories remains discouraged.)
6523 Font packages may, instead of placing files directly in
6524 the X font directories listed above, provide symbolic links in
6525 the font directory which point to the files' actual location
6526 in the filesystem. Such a location should comply with the
6530 Font packages should not contain both 75dpi and 100dpi
6531 versions of a font. If both are available, they should be
6532 provided in separate binary packages with "-75dpi" or "-100dpi"
6533 appended to the names of the packages containing the
6534 corresponding fonts.
6537 Fonts destined for the <tt>misc</tt> subdirectory should
6538 not be included in the same package as 75dpi or 100dpi fonts;
6539 instead, they should be provided in a separate package with
6540 "-misc" appended to its name.
6543 Font packages <em>must not</em> provide the files
6544 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6545 <tt>fonts.scale</tt> in a font directory.
6546 <list compact="compact">
6548 <tt>fonts.dir</tt> files must not be provided at
6552 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6553 files, if needed, should be provided in the
6555 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6556 where <em>fontdir</em> is the name of the
6558 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6559 package's corresponding fonts are stored (e.g.,
6560 <tt>75dpi</tt> or <tt>misc</tt>),
6561 <em>package</em> is the name of the package that
6562 provides these fonts, and <em>extension</em> is
6563 either <tt>scale</tt> or <tt>alias</tt>,
6564 whichever corresponds to the file
6570 Font packages must declare a dependency on
6571 <tt>xutils</tt> and, in the package
6572 post-installation and post-removal scripts, invoke the
6573 <tt>mkfontdir</tt> command on each directory into
6574 which they installed fonts.
6577 Font packages that provide one or more
6578 <tt>fonts.scale</tt> files as described above must declare a
6579 versioned dependency on <tt>xutils (>=
6580 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6581 directory into which they installed fonts
6582 <em>before</em> invoking <tt>mkfontdir</tt> on that
6583 directory. This invocation must occur in both the
6584 post-installation and post-removal scripts.
6587 Font packages that provide one or more
6588 <tt>fonts.alias</tt> files as described above must
6589 declare a versioned dependency on <tt>xutils
6590 (>= 4.0.2)</tt> and, in the package
6591 post-installation and post-removal scripts, invoke
6592 <tt>update-fonts-alias</tt> on each directory into
6593 which they installed fonts.
6596 Font packages must not provide alias names for the
6597 fonts they include which collide with alias names already in
6598 use by fonts already packaged.
6601 Font packages must not provide fonts with the same XLFD
6602 registry name as another font already packaged.
6608 <em>Application defaults</em> files must be installed in the
6609 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6610 localized subdirectory of <tt>/etc/X11/</tt> as described in
6611 the <em>X Toolkit Intrinsics - C Language Interface</em>
6612 manual is also permitted). They must be registered as
6613 <em>conffile</em>s or handled as configuration files. For
6614 programs that are not linked against the X Toolkit (Xt)
6615 library, customization of programs' X resources may also be
6616 supported with the provision of a file with the same name as
6617 that of the package placed in the
6618 <tt>/etc/X11/Xresources/</tt> directory, which must
6619 registered as a <em>conffile</em> or handled as a
6620 configuration file. <em>Important:</em> packages that
6621 install files into the <tt>/etc/X11/Xresources/</tt>
6622 directory <em>must</em> declare a conflict with <tt>xbase
6623 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6624 possible for the installing package to destroy a
6625 previously-existing <tt>/etc/X11/Xresources</tt> file which
6626 had been customized by the system administrator.
6630 <em>Packages using the X Window System should abide by the
6631 FHS standard whenever possible</em>; they should install
6632 binaries, libraries, manual pages, and other files in
6633 FHS-mandated locations wherever possible. This means that
6634 files must not be installed into <tt>/usr/X11R6/bin/</tt>,
6635 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt>
6636 unless this is necessary for the package to operate
6637 properly. Configuration files for window managers and
6638 display managers should be placed in a subdirectory of
6639 <tt>/etc/X11/</tt> corresponding to the package name due
6640 to these programs' tight integration with the mechanisms
6641 of the X Window System. Application-level programs should
6642 use the <tt>/etc/</tt> directory unless otherwise mandated
6643 by policy. The installation of files into subdirectories
6644 of <tt>/usr/X11R6/include/X11/</tt> and
6645 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6646 package maintainers should determine if subdirectories of
6647 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6648 instead (symlinks from the X11R6 directories to
6649 FHS-compliant locations is encouraged if the program is
6650 not easily configured to look elsewhere for its files).
6651 Packages must not provide or install files into the
6652 directories <tt>/usr/bin/X11/</tt>,
6653 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6654 Files within a package should, however, make reference to
6655 these directories, rather than their X11R6-named
6656 counterparts <tt>/usr/X11R6/bin/</tt>,
6657 <tt>/usr/X11R6/include/X11/</tt>, and
6658 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6659 referred to have not been moved to FHS-compliant
6664 <em>Programs that require the non-DFSG-compliant OSF/Motif
6665 library</em> should be compiled against and tested with
6666 LessTif (a free re-implementation of Motif) instead. If the
6667 maintainer judges that the program or programs do not work
6668 sufficiently well with LessTif to be distributed and
6669 supported, but do so when compiled against Motif, then two
6670 versions of the package should be created; one linked
6671 statically against Motif and with <tt>-smotif</tt> appended
6672 to the package name, and one linked dynamically against
6673 Motif and with <tt>-dmotif</tt> appended to the package
6674 name. Both Motif-linked versions are dependent upon
6675 non-DFSG-compliant software and thus cannot be uploaded to
6676 the main distribution; if the software is itself
6677 DFSG-compliant it may be uploaded to the contrib
6678 distribution. While known existing versions of OSF/Motif
6679 permit unlimited redistribution of binaries linked against
6680 the library (whether statically or dynamically), it is the
6681 package maintainer's responsibility to determine whether
6682 this is permitted by the license of the copy of OSF/Motif in
6683 his or her possession.
6688 <heading>Perl programs and modules</heading>
6690 Perl programs and modules should follow the current Perl
6691 policy as defined in the file found on
6692 <ftpsite>ftp.debian.org</ftpsite> in
6693 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
6694 or your local mirror. In addition, it is included in the
6695 <tt>debian-policy</tt> package.
6700 <heading>Emacs lisp programs</heading>
6703 Please refer to the `Debian Emacs Policy' (documented in
6704 <tt>debian-emacs-policy.gz</tt> of the
6705 <prgn>emacsen-common</prgn> package) for details of how to
6706 package emacs lisp programs.</p></sect>
6710 <heading>Games</heading>
6713 The permissions on /var/games are 755
6714 <tt>root.root</tt>.</p>
6717 Each game decides on its own security policy.</p>
6720 Games which require protected, privileged access to
6721 high-score files, savegames, etc., may be made
6722 set-<em>group</em>-id (mode 2755) and owned by
6723 <tt>root.games</tt>, and use files and directories with
6724 appropriate permissions (770 <tt>root.games</tt>, for
6725 example). They must not be made
6726 set-<em>user</em>-id, as this causes security problems. (If
6727 an attacker can subvert any set-user-id game they can
6728 overwrite the executable of any other, causing other players
6729 of these games to run a Trojan horse program. With a
6730 set-group-id game the attacker only gets access to less
6731 important game data, and if they can get at the other
6732 players' accounts at all it will take considerably more
6736 Some packages, for example some fortune cookie programs, are
6737 configured by the upstream authors to install with their
6738 data files or other static information made unreadable so
6739 that they can only be accessed through set-id programs
6740 provided. You should not do this in a Debian package: anyone can
6741 download the <tt>.deb</tt> file and read the data from it,
6742 so there is no point making the files unreadable. Not
6743 making the files unreadable also means that you don't have
6744 to make so many programs set-id, which reduces the risk of a
6748 As described in the FHS, binaries of games should be
6749 installed in the directory <tt>/usr/games</tt>. This also
6750 applies to games that use the X Window System. Manual pages
6751 for games (X and non-X games) should be installed in
6752 <tt>/usr/share/man/man6</tt>.</p>
6756 <chapt><heading>Documentation</heading>
6760 <heading>Manual pages</heading>
6763 You should install manual pages in <prgn>nroff</prgn> source
6764 form, in appropriate places under <tt>/usr/share/man</tt>. You
6765 should only use sections 1 to 9 (see the FHS for more
6766 details). You must not install a preformatted `cat
6770 Each program, utility, and function should have an
6771 associated manpage included in the same package. It is
6772 suggested that all configuration files also have a manual
6773 page included as well.
6777 If no manual page is available for a particular program,
6778 utility, function or configuration file and this is reported as a bug on
6779 debian-bugs, a symbolic link from the requested manual page
6780 to the <manref name="undocumented" section="7"> manual page
6781 may be provided. This symbolic link can be created from
6782 <tt>debian/rules</tt> like this:
6783 <example compact="compact">
6784 ln -s ../man7/undocumented.7.gz \
6785 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6787 This manpage claims that the lack of a manpage has been
6788 reported as a bug, so you may only do this if it really has
6789 (you can report it yourself, if you like). Do not close the
6790 bug report until a proper manpage is available.</p>
6793 You may forward a complaint about a missing manpage to the
6794 upstream authors, and mark the bug as forwarded in the
6795 Debian bug tracking system. Even though the GNU Project do
6796 not in general consider the lack of a manpage to be a bug,
6797 we do; if they tell you that they don't consider it a bug
6798 you should leave the bug in our bug tracking system open
6802 Manual pages should be installed compressed using <tt>gzip
6806 If one manpage needs to be accessible via several names it
6807 is better to use a symbolic link than the <tt>.so</tt>
6808 feature, but there is no need to fiddle with the relevant
6809 parts of the upstream source to change from <tt>.so</tt> to
6810 symlinks: don't do it unless it's easy. You should not create hard
6811 links in the manual page directories, nor put
6812 absolute filenames in <tt>.so</tt> directives. The filename
6813 in a <tt>.so</tt> in a manpage should be relative to the
6814 base of the manpage tree (usually
6815 <tt>/usr/share/man</tt>).</p></sect>
6819 <heading>Info documents</heading>
6822 Info documents should be installed in <tt>/usr/share/info</tt>.
6823 They should be compressed with <tt>gzip -9</tt>.</p>
6826 Your package should call <prgn>install-info</prgn> to update the Info
6828 file, in its post-installation script:
6829 <example compact="compact">
6830 install-info --quiet --section Development Development \
6831 /usr/share/info/foobar.info
6835 It is a good idea to specify a section for the location of
6836 your program; this is done with the <tt>--section</tt>
6837 switch. To determine which section to use, you should look
6838 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6839 relevant (or create a new section if none of the current
6840 sections are relevant). Note that the <tt>--section</tt>
6841 flag takes two arguments; the first is a regular expression
6842 to match (case-insensitively) against an existing section,
6843 the second is used when creating a new one.</p>
6846 You should remove the entries in the pre-removal script:
6847 <example compact="compact">
6848 install-info --quiet --remove /usr/share/info/foobar.info
6852 If <prgn>install-info</prgn> cannot find a description entry
6853 in the Info file you must supply one. See <manref
6854 name="install-info" section="8"> for details.</p>
6858 <heading>Additional documentation</heading>
6861 Any additional documentation that comes with the package may
6862 be installed at the discretion of the package maintainer.
6863 Text documentation should be installed in a directory
6864 <tt>/usr/share/doc/<var>package</var></tt>, where
6865 <var>package</var> is the name of the package, and
6866 compressed with <tt>gzip -9</tt> unless it is small.</p>
6869 If a package comes with large amounts of documentation which
6870 many users of the package will not require you should create
6871 a separate binary package to contain it, so that it does not
6872 take up disk space on the machines of users who do not need
6873 or want it installed.</p>
6876 It is often a good idea to put text information files
6877 (<tt>README</tt>s, changelogs, and so forth) that come with
6878 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6879 in the binary package. However, you don't need to install
6880 the instructions for building and installing the package, of
6884 Files in <tt>/usr/share/doc</tt> should not be referenced by
6885 any program, and the system administrator should be able to
6886 delete them without causing any programs to break. Any files
6887 that are referenced by programs but are also useful as
6888 standalone documentation should be installed under
6889 <tt>/usr/share/<package>/</tt> and symlinked in
6890 <tt>/usr/share/doc/<package>/</tt>.
6896 <heading>Accessing the documentation</heading>
6899 Former Debian releases placed all additional documentation
6900 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6902 <tt>/usr/share/doc/<var>package</var></tt>, each package
6903 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6904 that points to the new location of its documentation in
6905 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6906 symlinks will be removed in the future, but they have to be
6907 there for compatibility reasons until all packages have
6908 moved and the policy is changed accordingly.</footnote>.
6909 The symlink must be created when the package is installed;
6910 it cannot be contained in the package itself due to problems
6911 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6912 this is to put the following in the package's
6913 <prgn>postinst</prgn>:
6914 <example compact="compact">
6915 if [ "$1" = "configure" ]; then
6916 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6917 -a -d /usr/share/doc/#PACKAGE# ]; then
6918 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6922 And the following in the package's <prgn>prerm</prgn>:
6923 <example compact="compact">
6924 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6925 -a -L /usr/doc/#PACKAGE# ]; then
6926 rm -f /usr/doc/#PACKAGE#
6933 <heading>Preferred documentation formats</heading>
6936 The unification of Debian documentation is being carried out
6940 If your package comes with extensive documentation in a
6941 mark up format that can be converted to various other formats
6942 you should if possible ship HTML versions in a binary
6943 package, in the directory
6944 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6947 <p>The rationale: The important thing here is that HTML
6948 docs should be available in <em>some</em> package, not
6949 necessarily in the main binary package, though. </p>
6954 Other formats such as PostScript may be provided at your
6958 <sect id="copyrightfile">
6959 <heading>Copyright information</heading>
6962 Every package must be accompanied by a verbatim copy of its
6963 copyright and distribution license in the file
6964 /usr/share/doc/<package>/copyright. This file must
6965 neither be compressed nor be a symbolic link.</p>
6968 In addition, the copyright file must say where the upstream
6969 sources (if any) were obtained, and should explain briefly what
6970 modifications were made in the Debian version of the package
6971 compared to the upstream one. It should name the original
6972 authors of the package and the Debian maintainer(s) who were
6973 involved with its creation.</p>
6976 A copy of the file which will be installed in
6977 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6978 in <tt>debian/copyright</tt>.</p>
6982 /usr/share/doc/<package> may be a symbolic link to a
6983 directory in /usr/share/doc only if two packages both come from
6984 the same source and the first package has a "Depends"
6985 relationship on the second. These rules are important
6986 because copyrights must be extractable by mechanical
6990 Packages distributed under the UCB BSD license, the Artistic
6991 license, the GNU GPL, and the GNU LGPL should refer to the
6992 files /usr/share/common-licenses/BSD,
6993 /usr/share/common-licenses/Artistic,
6994 /usr/share/common-licenses/GPL, and
6995 /usr/share/common-licenses/LGPL.
6998 Why "licenses" and not "copyright"? Because
6999 <tt>/usr/doc/copyright</tt> used to contain all the
7000 copyright files, plus the four common licenses GPL,
7001 LGPL, Artistic and BSD. Now individual copyright files
7002 for packages are no longer in a common directory. Once
7003 <tt>/usr/doc/copyright</tt> is almost empty it makes
7004 sense to rename "copyright" to "licenses"
7007 Why "common-licenses" and not "licenses"? Because if I
7008 put just "licenses" I'm sure I will receive a bug report
7009 saying "license foo is not included in the licenses
7010 directory. They are not all the licenses, just a few
7011 common ones. I could use /usr/share/doc/common-licenses
7012 but I think this is too long, and, after all, the GPL
7013 does not "document" anything, it is merely a license.
7019 You should not use the copyright file as a general <tt>README</tt>
7020 file. If your package has such a file it should be
7021 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
7022 <tt>README.Debian</tt> or some other appropriate place.</p>
7026 <heading>Examples</heading>
7029 Any examples (configurations, source files, whatever),
7030 should be installed in a directory
7031 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7032 files should not be referenced by any program: they're there
7033 for the benefit of the system administrator and users, as
7034 documentation only. Architecture-specific example files
7035 should be installed in a directory
7036 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
7037 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
7038 to files in it. Or the latter directory may be a symlink to
7042 <sect id="instchangelog">
7043 <heading>Changelog files</heading>
7046 Packages that are not Debian-native must contain a copy of
7047 <tt>debian/changelog</tt> file from the Debian source tree
7048 in <tt>/usr/share/doc/<var>package</var></tt> as
7049 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7050 available, it should be accessible as
7051 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7052 plain text. If the upstream changelog is distributed in
7053 HTML, it should be made available in that form as
7054 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7055 and the <tt>changelog.gz</tt> should be generated using, eg,
7056 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
7057 do not already conform to this naming convention, then this
7058 may be achieved either by renaming the files, or adding a
7059 symbolic link, at the maintainer's discretion.
7062 Rationale: People should not have to look into two
7063 places for upstream changelogs merely because they are
7071 All these files should be installed compressed using <tt>gzip -9</tt>,
7072 as they will become large with time even if they start out
7077 If the package has only one changelog which is used both as
7078 the Debian changelog and the upstream one because there is
7079 no separate upstream maintainer then that changelog should
7080 usually be installed as
7081 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7082 there is a separate upstream maintainer, but no upstream
7083 changelog, then the Debian changelog should still be called
7084 <tt>changelog.Debian.gz</tt>.</p>