1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
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 name="Debconf stats">] currently use
1093 <package>debconf</package> to prompt the user at
1094 install time, and this number is growing daily. The
1095 benefits of using debconf are briefly explained at
1097 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1098 name="Debconf introduction">; they include
1099 preconfiguration, (mostly) noninteractive
1100 installation, elimination of redundant prompting,
1101 consistency of user interface, etc.
1104 With this increasing number of packages using
1105 <package>debconf</package>, plus the existance of a
1106 nascent second implementation of the Debian
1107 configuration management system
1108 (<package>cdebconf</package>), and the stabalization
1109 of the protocol these things use, the time has
1110 finally come to reflect the use of these things in
1117 Packages which use the Debian Configuration management
1118 specification may contain an additional
1119 <file>config</file> script and a <file>templates</file>
1120 file in their control archive. The <prgn>config</prgn>
1121 script might be run before the <prgn>preinst</prgn>
1122 script, and before the package is unpacked or any of its
1123 dependancies or pre-dependancies are satisfied.
1124 Therefore it must work using only the tools present in
1125 <em>essential</em> packages.
1128 <package>Debconf</package> or another tool that
1129 implements the Debian Configuration management
1130 specification will also be installed, and any
1131 versioned dependencies on it will be satisfied
1132 before preconfiguration begins.
1138 Packages should try to minimize the amount of prompting
1139 they need to do, and they should ensure that the user
1140 will only ever be asked each question once. This means
1141 that packages should try to use appropriate shared
1142 configuration files (such as <tt>/etc/papersize</tt> and
1143 <tt>/etc/news/server</tt>), and shared
1144 <package>debconf</package> variables rather than each
1145 prompting for their own list of required pieces of
1150 It also means that an upgrade should not ask the same
1151 questions again, unless the user has used <tt>dpkg
1152 --purge</tt> to remove the package's configuration. The
1153 answers to configuration questions should be stored in an
1154 appropriate place in <tt>/etc</tt> so that the user can
1155 modify them, and how this has been done should be
1159 If a package has a vitally important piece of
1160 information to pass to the user (such as "don't run me
1161 as I am, you must edit the following configuration files
1162 first or you risk your system emitting badly-formatted
1163 messages"), it should display this in the
1164 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1165 prompt the user to hit return to acknowledge the
1166 message. Copyright messages do not count as vitally
1167 important (they belong in
1168 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1169 neither do instructions on how to use a program (these
1170 should be in on-line documentation, where all the users
1174 Any necessary prompting should almost always be confined
1175 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1176 script. If it is done in the <prgn>postinst</prgn>, it
1177 should be protected with a conditional so that
1178 unnecessary prompting doesn't happen if a package's
1179 installation fails and the <prgn>postinst</prgn> is
1180 called with <tt>abort-upgrade</tt>,
1181 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1186 <heading>Source packages</heading>
1188 <sect1 id="standardsversion">
1189 <heading>Standards conformance</heading>
1192 In the source package's <tt>Standards-Version</tt> control
1193 field, you must specify the most recent version number of
1194 this policy document with which your package complies.
1195 The current version number is &version;.
1199 This information may be used to file bug reports
1200 automatically if your package becomes too much out of
1205 The version number has four components: major and minor
1206 version number and major and minor patch level. When the
1207 standards change in a way that requires every package to
1208 change the major number will be changed. Significant
1209 changes that will require work in many packages will be
1210 signaled by a change to the minor number. The major patch
1211 level will be changed for any change to the meaning of the
1212 standards, however small; the minor patch level will be
1213 changed when only cosmetic, typographical or other edits
1214 are made which neither change the meaning of the document
1215 nor affect the contents of packages.</p>
1218 Thus only the first three components of the policy version
1219 are significant in the <em>Standards-Version</em> control
1220 field, and so either these three components or the all
1221 four components may be specified.
1224 In the past, people specified the full version number
1225 in the Standards-Version field, for example `2.3.0.0'.
1226 Since minor patch-level changes don't introduce new
1227 policy, it was thought it would be better to relax
1228 policy and only require the first 3 components to be
1229 specified, in this example `2.3.0'. All four
1230 components may still be used if someone wishes to do
1237 You should regularly, and especially if your package has
1238 become out of date, check for the newest Policy Manual
1239 available and update your package, if necessary. When your
1240 package complies with the new standards you should update the
1241 <tt>Standards-Version</tt> source package field and
1245 See the file <tt>upgrading-checklist</tt> for
1246 information about policy which has changed between
1247 different versions of this document.
1255 <heading>Package relationships</heading>
1258 Source packages should specify which binary packages they
1259 require to be installed or not to be installed in order to
1260 build correctly. For example, if building a package
1261 requires a certain compiler, then the compiler should be
1262 specified as a build-time dependency.
1266 It is not necessary to explicitly specify build-time
1267 relationships on a minimal set of packages that are always
1268 needed to compile, link and put in a Debian package a
1269 standard "Hello World!" program written in C or C++. The
1270 required packages are called <em>build-essential</em>, and
1271 an informational list can be found in
1272 <tt>/usr/share/doc/build-essential/list</tt> (which is
1273 contained in the <tt>build-essential</tt>
1277 <list compact="compact">
1279 <p>This allows maintaining the list separately
1280 from the policy documents (the list does not
1281 need the kind of control that the policy
1287 Having a separate package allows one to install
1288 the build-essential packages on a machine, as
1289 well as allowing other packages such as task
1290 packages to require installation of the
1291 build-essential packages using the depends
1297 The separate package allows bug reports against
1298 the list to be categorized separately from
1299 the policy management process in the BTS.
1309 When specifying the set of build-time dependencies, one
1310 should list only those packages explicitly required by the
1311 build. It is not necessary to list packages which are
1312 required merely because some other package in the list of
1313 build-time dependencies depends on them.
1316 The reason for this is that dependencies change, and
1317 you should list all those packages, and <em>only</em>
1318 those packages that <em>you</em> need directly. What
1319 others need is their business. For example, if you
1320 only link against <tt>libimlib</tt>, you will need to
1321 build-depend on <package>libimlib2-dev</package> but
1322 not against any <tt>libjpeg*</tt> packages, even
1323 though <tt>libimlib2-dev</tt> currently depends on
1324 them: installation of <package>libimlib2-dev</package>
1325 will automatically ensure that all of its run-time
1326 dependencies are satisfied.
1332 If build-time dependencies are specified, it must be
1333 possible to build the package and produce working binaries
1334 on a system with only essential and build-essential
1335 packages installed and also those required to satisfy the
1336 build-time relationships (including any implied
1337 relationships). In particular, this means that version
1338 clauses should be used rigorously in build-time
1339 relationships so that one cannot produce bad or
1340 inconsistently configured packages when the relationships
1341 are properly satisfied.
1345 <heading>Changes to the upstream sources</heading>
1348 If changes to the source code are made that are not
1349 specific to the needs of the Debian system, they should be
1350 sent to the upstream authors in whatever form they prefer
1351 so as to be included in the upstream version of the
1355 If you need to configure the package differently for
1356 Debian or for Linux, and the upstream source doesn't
1357 provide a way to do so, you should add such configuration
1358 facilities (for example, a new <prgn>autoconf</prgn> test
1359 or <tt>#define</tt>) and send the patch to the upstream
1360 authors, with the default set to the way they originally
1361 had it. You can then easily override the default in your
1362 <tt>debian/rules</tt> or wherever is appropriate.</p>
1365 You should make sure that the <prgn>configure</prgn> utility
1366 detects the correct architecture specification string
1367 (refer to <ref id="arch-spec"> for details).</p>
1370 If you need to edit a <prgn>Makefile</prgn> where
1371 GNU-style <prgn>configure</prgn> scripts are used, you
1372 should edit the <tt>.in</tt> files rather than editing the
1373 <prgn>Makefile</prgn> directly. This allows the user to
1374 reconfigure the package if necessary. You should
1375 <em>not</em> configure the package and edit the generated
1376 <prgn>Makefile</prgn>! This makes it impossible for
1377 someone else to later reconfigure the package.</p></sect1>
1381 <heading>Documenting your changes</heading>
1384 You should document your changes and updates to the source
1385 package properly in the <tt>debian/changelog</tt> file. (Note
1386 that mistakes in changelogs are usually best rectified by
1387 making a new changelog entry rather than "rewriting history"
1388 by editing old changelog entries.)</p>
1391 In non-experimental packages you must use a format for
1392 <tt>debian/changelog</tt> which is supported by the most
1393 recent released version of <prgn>dpkg</prgn>.
1396 If you wish to use an alternative format, you may do
1397 so as long as you include a parser for it in your
1398 source package. The parser must have an API
1399 compatible with that expected by
1400 <prgn>dpkg-genchanges</prgn> and
1401 <prgn>dpkg-gencontrol</prgn>. If there is general
1402 interest in the new format, you should contact the
1403 <package>dpkg</package> maintainer to have the parser
1404 script for it included in the <prgn>dpkg</prgn>
1405 package. (You will need to agree that the parser and
1406 its manpage may be distributed under the GNU GPL, just
1407 as the rest of `dpkg' is.)
1415 <heading>Error trapping in makefiles</heading>
1418 When <prgn>make</prgn> invokes a command in a makefile
1419 (including your package's upstream makefiles and
1420 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1421 means that <tt>sh</tt>'s usual bad error handling
1422 properties apply: if you include a miniature script as one
1423 of the commands in your makefile you'll find that if you
1424 don't do anything about it then errors are not detected
1425 and <prgn>make</prgn> will blithely continue after
1429 Every time you put more than one shell command (this
1430 includes using a loop) in a makefile command you
1431 must make sure that errors are trapped. For
1432 simple compound commands, such as changing directory and
1433 then running a program, using <tt>&&</tt> rather
1434 than semicolon as a command separator is sufficient. For
1435 more complex commands including most loops and
1436 conditionals you should include a separate <tt>set -e</tt>
1437 command at the start of every makefile command that's
1438 actually one of these miniature shell scripts.</p></sect1>
1442 <heading>Obsolete constructs and libraries</heading>
1445 The include file <prgn><varargs.h></prgn> is
1446 provided to support end-users compiling very old software;
1447 the library <tt>libtermcap</tt> is provided to support the
1448 execution of software which has been linked against it
1449 (either old programs or those such as Netscape which are
1450 only available in binary form).</p>
1453 Debian packages should be patched to use
1454 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1461 <chapt id="controlfields"><heading>Control files and their fields</heading>
1464 Many of the tools in the package management suite manipulate
1465 data represented in a common format, known as <em>control
1466 data</em>. The data is often stored in <em>control
1467 files</em>. Binary and source packages have control files,
1468 and the <tt>.changes</tt> files which control the installation
1469 of uploaded files are also in control file format.
1470 <prgn>Dpkg</prgn>'s internal databases are in a similar
1474 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1477 A control file consists of one or more paragraphs of fields.
1478 The paragraphs are separated by blank lines. Some control
1479 files allow only one paragraph; others allow several, in
1480 which case each paragraph usually refers to a different
1481 package. (For example, in source packages, the first
1482 paragraph refers to the source package, and later paragraphs
1483 refer to binary packages generated from the source.)
1487 Each paragraph consists of a series of data fields; each
1488 field consists of the field name, followed by a colon and
1489 then the data/value associated with that field. It ends at
1490 the end of the line. Horizontal whitespace (spaces and
1491 tabs) may occur immediately before or after the value and is
1492 ignored there; it is conventional to put a single space
1493 after the colon. For example, a field might be:
1494 <example compact="compact">
1497 the field name is <tt>Package</tt> and the field value
1502 Some fields' values may span several lines; in this case
1503 each continuation line <em>must</em> start with a space or
1504 tab. Any trailing spaces or tabs at the end of individual
1505 lines of a field value are ignored.
1509 Except where otherwise stated only a single line of data is
1510 allowed and whitespace is not significant in a field body.
1511 Whitespace must not appear inside names (of packages,
1512 architectures, files or anything else) or version numbers,
1513 or between the characters of multi-character version
1518 Field names are not case-sensitive, but it is usual to
1519 capitalize the field names using mixed case as shown below.
1523 Blank lines, or lines consisting only of spaces and tabs,
1524 are not allowed within field values or between fields - that
1525 would mean a new paragraph.
1530 <sect><heading>List of fields</heading>
1532 This list here is not supposed to be exhaustive. Most fields
1533 are dealt with elsewhere in this document.
1535 <sect1 id="f-Package"><heading><tt>Package</tt>
1539 The name of the binary package. Package names consist of
1540 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1541 (plus, minus and full stop).
1545 They must be at least two characters long and must start
1546 with an alphanumeric character and not be all digits. The
1547 use of lowercase package names is strongly recommended
1548 unless the package you're building (or referring to, in
1549 other fields) is already using uppercase.</p>
1552 <sect1 id="f-Version"><heading><tt>Version</tt>
1556 This lists the source or binary package's version number -
1557 see <ref id="versions">.
1563 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1567 The most recent version of the standards (the policy
1568 manual and associated texts) with which the package
1569 complies. This is updated manually when editing the
1570 source package to conform to newer standards; it can
1571 sometimes be used to tell when a package needs attention.
1572 Its format is described above; see
1573 <ref id="standardsversion">.
1578 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1582 In a <tt>.changes</tt> file or parsed changelog output
1583 this contains the (space-separated) name(s) of the
1584 distribution(s) where this version of the package should
1585 be installed. Valid distributions are determined by the
1586 archive maintainers.
1588 Current distribution names are:
1589 <taglist compact="compact">
1590 <tag><em>stable</em></tag>
1593 This is the current `released' version of Debian
1594 GNU/Linux. Once the distribution is
1595 <em>stable</em> only security fixes and other
1596 major bug fixes are allowed. When changes are
1597 made to this distribution, the release number is
1598 increased (for example: 2.2r1 becomes 2.2r2 then
1603 <tag><em>unstable</em></tag>
1606 This distribution value refers to the
1607 <em>developmental</em> part of the Debian
1608 distribution tree. New packages, new upstream
1609 versions of packages and bug fixes go into the
1610 <em>unstable</em> directory tree. Download from
1611 this distribution at your own risk.
1615 <tag><em>testing</em></tag>
1618 This distribution value refers to the
1619 <em>testing</em> part of the Debian distribution
1620 tree. It receives its packages from the
1621 unstable distribution after a short time lag to
1622 ensure that there are no major issues with the
1623 unstable packages. It is less prone to breakage
1624 than unstable, but still risky. It is not
1625 possible to upload packages directly to
1630 <tag><em>frozen</em></tag>
1633 From time to time, the <em>testing</em>
1634 distribution enters a state of `code-freeze' in
1635 anticipation of release as a <em>stable</em>
1636 version. During this period of testing only
1637 fixes for existing or newly-discovered bugs will
1638 be allowed. The exact details of this stage are
1639 determined by the Release Manager.
1643 <tag><em>experimental</em></tag>
1646 The packages with this distribution value are
1647 deemed by their maintainers to be high
1648 risk. Oftentimes they represent early beta or
1649 developmental packages from various sources that
1650 the maintainers want people to try, but are not
1651 ready to be a part of the other parts of the
1652 Debian distribution tree. Download at your own
1658 You should list <em>all</em> distributions that the
1659 package should be installed into.
1668 <chapt id="versions"><heading>Version numbering</heading>
1671 Every package has a version number recorded in its
1672 <tt>Version</tt> control file field.
1676 The package management system imposes an ordering on version
1677 numbers, so that it can tell whether packages are being up- or
1678 downgraded and so that package system front end applications
1679 can tell whether a package it finds available is newer than
1680 the one installed on the system. The version number format
1681 has the most significant parts (as far as comparison is
1682 concerned) at the beginning.
1686 The version number format is:
1687 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1691 The three components here are:
1693 <tag><var>epoch</var></tag>
1697 This is a single (generally small) unsigned integer. It
1698 may be omitted, in which case zero is assumed. If it is
1699 omitted then the <var>upstream_version</var> may not
1704 It is provided to allow mistakes in the version numbers
1705 of older versions of a package, and also a package's
1706 previous version numbering schemes, to be left behind.
1711 <tag><var>upstream_version</var></tag>
1715 This is the main part of the version number. It is
1716 usually the version number of the original (`upstream')
1717 package from which the <tt>.deb</tt> file has been made,
1718 if this is applicable. Usually this will be in the same
1719 format as that specified by the upstream author(s);
1720 however, it may need to be reformatted to fit into the
1721 package management system's format and comparison
1726 The comparison behavior of the package management system
1727 with respect to the <var>upstream_version</var> is
1728 described below. The <var>upstream_version</var>
1729 portion of the version number is mandatory.
1733 The <var>upstream_version</var> may contain only
1736 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1738 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1739 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1740 start with a digit. If there is no
1741 <var>debian_revision</var> then hyphens are not allowed;
1742 if there is no <var>epoch</var> then colons are not
1746 <tag><var>debian_revision</var></tag>
1750 This part of the version number specifies the version of
1751 the Debian package based on the upstream version. It
1752 may contain only alphanumerics and the characters
1753 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1754 compared in the same way as the
1755 <var>upstream_version</var> is.
1759 It is optional; if it isn't present then the
1760 <var>upstream_version</var> may not contain a hyphen.
1761 This format represents the case where a piece of
1762 software was written specifically to be turned into a
1763 Debian package, and so there is only one `debianization'
1764 of it and therefore no revision indication is required.
1768 It is conventional to restart the
1769 <var>debian_revision</var> at <tt>1</tt> each time the
1770 <var>upstream_version</var> is increased.
1774 The package management system will break the version
1775 number apart at the last hyphen in the string (if there
1776 is one) to determine the <var>upstream_version</var> and
1777 <var>debian_revision</var>. The absence of a
1778 <var>debian_revision</var> compares earlier than the
1779 presence of one (but note that the
1780 <var>debian_revision</var> is the least significant part
1781 of the version number).
1788 The <var>upstream_version</var> and <var>debian_revision</var>
1789 parts are compared by the package management system using the
1794 The strings are compared from left to right.
1798 First the initial part of each string consisting entirely of
1799 non-digit characters is determined. These two parts (one of
1800 which may be empty) are compared lexically. If a difference
1801 is found it is returned. The lexical comparison is a
1802 comparison of ASCII values modified so that all the letters
1803 sort earlier than all the non-letters.
1807 Then the initial part of the remainder of each string which
1808 consists entirely of digit characters is determined. The
1809 numerical values of these two parts are compared, and any
1810 difference found is returned as the result of the comparison.
1811 For these purposes an empty string (which can only occur at
1812 the end of one or both version strings being compared) counts
1817 These two steps (comparing and removing initial non-digit
1818 strings and initial digit strings) are repeated until a
1819 difference is found or both strings are exhausted.
1823 Note that the purpose of epochs is to allow us to leave behind
1824 mistakes in version numbering, and to cope with situations
1825 where the version numbering scheme changes. It is
1826 <em>not</em> intended to cope with version numbers containing
1827 strings of letters which the package management system cannot
1828 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1829 silly orderings (the author of this manual has heard of a
1830 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1831 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1832 <tt>2</tt> and so forth).
1836 If an upstream package has problematic version numbers they
1837 should be converted to a sane form for use in the
1838 <tt>Version</tt> field.
1842 <heading>Version numbers based on dates</heading>
1844 In general, Debian packages should use the same version
1845 numbers as the upstream sources.</p>
1848 However, in some cases where the upstream version number is
1849 based on a date (e.g., a development `snapshot' release) the
1850 package management system cannot handle these version
1851 numbers without epochs. For example, dpkg will consider
1852 `96May01' to be greater than `96Dec24'.</p>
1855 To prevent having to use epochs for every new upstream
1856 version, the version number should be changed to the
1857 following format in such cases: `19960501', `19961224'. It
1858 is up to the maintainer whether he/she wants to bother the
1859 upstream maintainer to change the version numbers upstream,
1863 Note that other version formats based on dates which are
1864 parsed correctly by the package management system should
1865 <em>not</em> be changed.</p>
1868 Native Debian packages (i.e., packages which have been
1869 written especially for Debian) whose version numbers include
1870 dates should always use the `YYYYMMDD' format.</p>
1874 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1876 <sect id="timestamps"><heading>Time Stamps</heading>
1878 Maintainers should preserve the modification times of the
1879 upstream source files in a package, as far as is reasonably
1883 The rationale is that there is some information conveyed
1884 by knowing the age of the file, for example, you could
1885 recognize that some documentation is very old by looking
1886 at the modification time, so it would be nice if the
1887 modification time of the upstream source would be
1894 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1895 main building script</heading>
1898 This file must be an executable makefile, and contains the
1899 package-specific recipes for compiling the package and
1900 building binary package(s) from the source.
1904 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1905 so that it can be invoked by saying its name rather than
1906 invoking <prgn>make</prgn> explicitly.
1910 Since an interactive <tt>debian/rules</tt> script makes it
1911 impossible to auto-compile that package and also makes it
1912 hard for other people to reproduce the same binary
1913 package, all <em>required targets</em> MUST be
1914 non-interactive. At a minimum, required targets are the
1915 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1916 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1917 <em>binary-indep</em>, and <em>build</em>. It also follows
1918 that any target that these targets depend on must also be
1923 The required and optional targets are as follows:
1925 <tag><tt>build</tt></tag>
1928 This should perform all non-interactive configuration
1929 and compilation of the package. If a package has an
1930 interactive pre-build configuration routine, the
1931 Debianized source package must either be built after
1932 this has taken place (so that the binary package can
1933 be built without rerunning the configuration) or the
1934 configuration routine modified to become
1935 non-interactive. (The latter is preferable if there
1936 are architecture-specific features detected by the
1937 configuration routine.)
1941 For some packages, notably ones where the same
1942 source tree is compiled in different ways to produce
1943 two binary packages, the <prgn>build</prgn> target
1944 does not make much sense. For these packages it is
1945 good enough to provide two (or more) targets
1946 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1947 for each of the ways of building the package, and a
1948 <prgn>build</prgn> target that does nothing. The
1949 <prgn>binary</prgn> target will have to build the
1950 package in each of the possible ways and make the
1951 binary package out of each.
1955 The <prgn>build</prgn> target must not do anything
1956 that might require root privilege.
1960 The <prgn>build</prgn> target may need to run the
1961 <prgn>clean</prgn> target first - see below.
1965 When a package has a configuration and build routine
1966 which takes a long time, or when the makefiles are
1967 poorly designed, or when <prgn>build</prgn> needs to
1968 run <prgn>clean</prgn> first, it is a good idea to
1969 <tt>touch build</tt> when the build process is
1970 complete. This will ensure that if <tt>debian/rules
1971 build</tt> is run again it will not rebuild the whole
1975 Another common way to do this is for <prgn>build</prgn>
1976 to depend on <prgn>build-stamp</prgn> and to do
1977 nothing else, and for the <prgn>build-stamp</prgn>
1978 target to do the building and to <tt>touch
1979 build-stamp</tt> on completion. This is
1980 especially useful if the build routine creates a
1981 file or directory called <tt>build</tt>; in such a
1982 case, <prgn>build</prgn> will need to be listed as
1983 a phony target (i.e., as a dependency of the
1984 <tt>.PHONY</tt> target). See the documentation of
1985 <prgn>make</prgn> for more information on phony
1992 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1993 <tt>binary-indep</tt>
1997 The <prgn>binary</prgn> target must be all that is
1998 necessary for the user to build the binary package(s)
1999 produced from this source package. All of these
2000 targets are required to be non-interactive. It is
2001 split into two parts: <prgn>binary-arch</prgn> builds
2002 the binary packages which are specific to a particular
2003 architecture, and <prgn>binary-indep</prgn> builds
2004 those which are not.
2008 <prgn>binary</prgn> may be (and commonly is) a target
2009 with no commands which simply depends on
2010 <prgn>binary-arch</prgn> and
2011 <prgn>binary-indep</prgn>.
2015 Each <prgn>binary-*</prgn> target should depend on
2016 the <prgn>build</prgn> target, above, so that the
2017 package is built if it has not been already. It
2018 should then create the relevant binary package(s),
2019 using <prgn>dpkg-gencontrol</prgn> to make their
2020 control files and <prgn>dpkg-deb</prgn> to build
2021 them and place them in the parent of the top level
2026 Both the <prgn>binary-arch</prgn> and
2027 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2028 If one of them has nothing to do (which will always be
2029 the case if the source generates only a single binary
2030 package, whether architecture-dependent or not), it
2031 must still exist and must always succeed.
2035 The <prgn>binary</prgn> targets must be invoked as
2039 The <prgn>fakeroot</prgn> package often allows one
2040 to build a package correctly even without being
2047 <tag><tt>clean</tt></tag>
2051 This must undo any effects that the <prgn>build</prgn>
2052 and <prgn>binary</prgn> targets may have had, except
2053 that it should leave alone any output files created in
2054 the parent directory by a run of a <prgn>binary</prgn>
2055 target. This target must be non-interactive.
2059 If a <prgn>build</prgn> file is touched at the end of
2060 the <prgn>build</prgn> target, as suggested above, it
2061 should be removed as the first action that
2062 <prgn>clean</prgn> performs, so that running
2063 <prgn>build</prgn> again after an interrupted
2064 <prgn>clean</prgn> doesn't think that everything is
2069 The <prgn>clean</prgn> target may need to be
2070 invoked as root if <prgn>binary</prgn> has been
2071 invoked since the last <prgn>clean</prgn>, or if
2072 <prgn>build</prgn> has been invoked as root (since
2073 <prgn>build</prgn> may create directories, for
2078 <tag><tt>get-orig-source</tt> (optional)</tag>
2082 This target fetches the most recent version of the
2083 original source package from a canonical archive site
2084 (via FTP or WWW, for example), does any necessary
2085 rearrangement to turn it into the original source
2086 tar file format described below, and leaves it in the
2091 This target may be invoked in any directory, and
2092 should take care to clean up any temporary files it
2097 This target is optional, but providing it if
2098 possible is a good idea.
2104 The <prgn>build</prgn>, <prgn>binary</prgn> and
2105 <prgn>clean</prgn> targets must be invoked with the current
2106 directory being the package's top-level directory.
2111 Additional targets may exist in <tt>debian/rules</tt>,
2112 either as published or undocumented interfaces or for the
2113 package's internal use.
2117 The architectures we build on and build for are determined
2118 by <prgn>make</prgn> variables using the utility
2119 <prgn>dpkg-architecture</prgn>. You can determine the
2120 Debian architecture and the GNU style architecture
2121 specification string for the build machine (the machine type
2122 we are building on) as well as for the host machine (the
2123 machine type we are building for). Here is a list of
2124 supported <prgn>make</prgn> variables:
2125 <list compact="compact">
2127 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2130 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2131 specification string)</p>
2134 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2135 <tt>DEB_*_GNU_TYPE</tt>)</p>
2138 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2139 <tt>DEB_*_GNU_TYPE</tt>)</p>
2141 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2142 the build machine or <tt>HOST</tt> for specification of the
2147 Backward compatibility can be provided in the rules file
2148 by setting the needed variables to suitable default
2149 values; please refer to the documentation of
2150 <prgn>dpkg-architecture</prgn> for details.
2154 It is important to understand that the <tt>DEB_*_ARCH</tt>
2155 string only determines which Debian architecture we are
2156 building on or for. It should not be used to get the CPU
2157 or system information; the GNU style variables should be
2162 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2166 This file records the changes to the Debian-specific parts of the
2170 Though there is nothing stopping an author who is also
2171 the Debian maintainer from using it for all their
2172 changes, it will have to be renamed if the Debian and
2173 upstream maintainers become different people. In such a
2174 case, however, it might be better to maintain the
2175 package as a non-native package.
2181 It has a special format which allows the package building
2182 tools to discover which version of the package is being
2183 built and find out other release-specific information.
2187 That format is a series of entries like this:
2188 <example compact="compact">
2189 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2191 * <var>change details</var>
2192 <var>more change details</var>
2193 * <var>even more change details</var>
2195 -- <var>maintainer name</var> <<var>email address</var>> <var>date</var>
2200 <var>package</var> and <var>version</var> are the source
2201 package name and version number.
2205 <var>distribution(s)</var> lists the distributions where
2206 this version should be installed when it is uploaded - it
2207 is copied to the <tt>Distribution</tt> field in the
2208 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2212 <var>urgency</var> is the value for the <tt>Urgency</tt>
2213 field in the <tt>.changes</tt> file for the upload. It is
2214 not possible to specify an urgency containing commas; commas
2215 are used to separate
2216 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2217 <prgn>dpkg</prgn> changelog format (though there is
2218 currently only one useful <var>keyword</var>,
2222 Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
2223 <tt>high</tt> and <tt>critical</tt>. They have an
2224 effect on how quickly a package will be considered for
2225 inclusion into the <tt>testing</tt> distribution, and
2226 give an indication of the importance of any fixes
2227 included in this upload.
2233 The change details may in fact be any series of lines
2234 starting with at least two spaces, but conventionally each
2235 change starts with an asterisk and a separating space and
2236 continuation lines are indented so as to bring them in
2237 line with the start of the text above. Blank lines may be
2238 used here to separate groups of changes, if desired.
2242 If this upload resolves bugs recorded in the Bug Tracking
2243 System (BTS), they may be automatically closed on the
2244 inclusion of this package into the Debian archive by
2245 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2246 in the change details.
2249 To be precise, the string should match the following
2250 Perl regular expression:
2252 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2254 Then all of the bug numbers listed will be closed by the
2255 archive maintenance script (<prgn>katie</prgn>), or in
2256 the case of an NMU, marked as fixed.
2262 The maintainer name and email address used in the changelog
2263 should be the details of the person uploading <em>this</em>
2264 version. They are <em>not</em> necessarily those of the
2265 usual package maintainer. The information here will be
2266 copied to the <tt>Changed-By</tt> field in the
2267 <tt>.changes</tt> file, and then later used to send an
2268 acknowledgement when the upload has been installed.
2272 The <var>date</var> should be in RFC822 format
2275 This is generated by the <prgn>822-date</prgn>
2278 </footnote>; it should include the time zone specified
2279 numerically, with the time zone name or abbreviation
2280 optionally present as a comment in parentheses.
2284 The first `title' line with the package name should start
2285 at the left hand margin; the `trailer' line with the
2286 maintainer and date details should be preceded by exactly
2287 one space. The maintainer details and the date must be
2288 separated by exactly two spaces.
2291 <sect1><heading>Defining alternative changelog formats</heading>
2294 It is possible to use a different format to the standard
2295 one, by providing a parser for the format you wish to
2299 A changelog parser must not interact with the user at
2305 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2306 and variable substitutions </heading>
2309 When <prgn>dpkg-gencontrol</prgn>,
2310 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2311 generate control files they perform variable substitutions
2312 on their output just before writing it. Variable
2313 substitutions have the form
2314 <tt>${<var>variable-name</var>}</tt>. The optional file
2315 <tt>debian/substvars</tt> contains variable substitutions to
2316 be used; variables can also be set directly from
2317 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2318 source packaging commands, and certain predefined variables
2323 The <tt>debian/substvars</tt> file is usually generated and
2324 modified dynamically by <tt>debian/rules</tt> targets; in
2325 this case it must be removed by the <prgn>clean</prgn>
2330 See <manref name="dpkg-source" section="1"> for full
2331 details about source variable substitutions, including the
2332 format of <tt>debian/substvars</tt>.</p>
2335 <sect id="debianfiles"><heading><tt>debian/files</tt>
2339 This file is not a permanent part of the source tree; it
2340 is used while building packages to record which files are
2341 being generated. <prgn>dpkg-genchanges</prgn> uses it
2342 when it generates a <tt>.changes</tt> file.
2346 It should not exist in a shipped source package, and so it
2347 (and any backup files or temporary files such as
2351 <tt>files.new</tt> is used as a temporary file by
2352 <prgn>dpkg-gencontrol</prgn> and
2353 <prgn>dpkg-distaddfile</prgn> - they write a new
2354 version of <tt>files</tt> here before renaming it,
2355 to avoid leaving a corrupted copy if an error
2358 </footnote>) should be removed by the
2359 <prgn>clean</prgn> target. It may also be wise to
2360 ensure a fresh start by emptying or removing it at the
2361 start of the <prgn>binary</prgn> target.
2365 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2366 package, it adds an entry to <tt>debian/files</tt> for the
2367 <tt>.deb</tt> file that will be created when <tt>dpkg-deb
2368 --build</tt> is run for that binary package. So for most
2369 packages all that needs to be done with this file is to
2370 delete it in the <prgn>clean</prgn> target.
2374 If a package upload includes files besides the source
2375 package and any binary packages whose control files were
2376 made with <prgn>dpkg-gencontrol</prgn> then they should be
2377 placed in the parent of the package's top-level directory
2378 and <prgn>dpkg-distaddfile</prgn> should be called to add
2379 the file to the list in <tt>debian/files</tt>.</p>
2382 <sect id="restrictions"><heading>Restrictions on objects in source packages
2386 The source package may not contain any hard links
2389 This is not currently detected when building source
2390 packages, but only when extracting
2394 Hard links may be permitted at some point in the
2395 future, but would require a fair amount of
2398 </footnote>, device special files, sockets or setuid or
2402 Setgid directories are allowed.
2407 <sect id="descriptions"><heading>Descriptions of packages - the
2408 <tt>Description</tt> field </heading>
2411 The description is intended to describe the program to a user
2412 who has never met it before so that they know whether they
2413 want to install it. It should also give information about the
2414 significant dependencies and conflicts between this package
2415 and others, so that the user knows why these dependencies and
2416 conflicts have been declared.
2419 <sect1><heading>Notes about writing descriptions
2423 The single line synopsis should be kept brief - certainly
2424 under 80 characters.
2428 Do not include the package name in the synopsis line. The
2429 display software knows how to display this already, and you
2430 do not need to state it. Remember that in many situations
2431 the user may only see the synopsis line - make it as
2432 informative as you can.
2436 Do not try to continue the single line synopsis into the
2437 extended description. This will not work correctly when
2438 the full description is displayed, and makes no sense
2439 where only the summary (the single line synopsis) is
2444 The extended description should describe what the package
2445 does and how it relates to the rest of the system (in terms
2446 of, for example, which subsystem it is which part of).
2450 The description field needs to make sense to anyone, even
2451 people who have no idea about any of the things the
2455 The blurb that comes with a program in its
2456 announcements and/or <prgn>README</prgn> files is
2457 rarely suitable for use in a description. It is
2458 usually aimed at people who are already in the
2459 community where the package is used.
2465 Put important information first, both in the synopsis and
2466 extended description. Sometimes only the first part of the
2467 synopsis or of the description will be displayed. You can
2468 assume that there will usually be a way to see the whole
2469 extended description.
2473 You may include information about dependencies and so forth
2474 in the extended description, if you wish.
2478 Do not use tab characters. Their effect is not predictable.
2486 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2487 and installation procedure
2490 <sect><heading>Introduction to package maintainer scripts
2494 It is possible to supply scripts as part of a package which
2495 the package management system will run for you when your
2496 package is installed, upgraded or removed.
2500 These scripts are the files <prgn>preinst</prgn>,
2501 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2502 control area of the package. They must be proper executable
2503 files; if they are scripts (which is recommended), they must
2504 start with the usual <tt>#!</tt> convention. They should be
2505 readable and executable by anyone, and not world-writable.
2509 The package management system looks at the exit status from
2510 these scripts. It is important that they exit with a
2511 non-zero status if there is an error, so that the package
2512 management system can stop its processing. For shell
2513 scripts this means that you <em>almost always</em> need to
2514 use <tt>set -e</tt> (this is usually true when writing shell
2515 scripts, in fact). It is also important, of course, that
2516 they don't exit with a non-zero status if everything went
2521 When a package is upgraded a combination of the scripts from
2522 the old and new packages is called during the upgrade
2523 procedure. If your scripts are going to be at all
2524 complicated you need to be aware of this, and may need to
2525 check the arguments to your scripts.
2529 Broadly speaking the <prgn>preinst</prgn> is called before
2530 (a particular version of) a package is installed, and the
2531 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2532 before (a version of) a package is removed and the
2533 <prgn>postrm</prgn> afterwards.
2537 Programs called from maintainer scripts should not normally
2538 have a path prepended to them. Before installation is
2539 started, the package management system checks to see if the
2540 programs <prgn>ldconfig</prgn>,
2541 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2542 and <prgn>update-rc.d</prgn> can be found via the
2543 <tt>PATH</tt> environment variable. Those programs, and any
2544 other program that one would expect to be on the
2545 <tt>PATH</tt>, should thus be invoked without an absolute
2546 pathname. Maintainer scripts should also not reset the
2547 <tt>PATH</tt>, though they might choose to modify it by
2548 prepending or appending package-specific directories. These
2549 considerations really apply to all shell scripts.</p>
2553 <heading>Maintainer scripts Idempotency</heading>
2556 It is necessary for the error recovery procedures that the
2557 scripts be idempotent. This means that if it is run
2558 successfully, and then it is called again, it doesn't bomb
2559 out or cause any harm, but just ensures that everything is
2560 the way it ought to be. If the first call failed, or
2561 aborted half way through for some reason, the second call
2562 should merely do the things that were left undone the first
2563 time, if any, and exit with a success status if everything
2567 This is so that if an error occurs, the user interrupts
2568 <prgn>dpkg</prgn> or some other unforeseen circumstance
2569 happens you don't leave the user with a badly-broken
2570 package when <prgn>dpkg</prgn> attempts to repeat the
2578 <heading>Controlling terminal for maintainer scripts</heading>
2581 The maintainer scripts are guaranteed to run with a
2582 controlling terminal and can interact with the user.
2583 If they need to prompt for passwords, do full-screen
2584 interaction or something similar you should do these
2585 things to and from <tt>/dev/tty</tt>, since
2586 <prgn>dpkg</prgn> will at some point redirect scripts'
2587 standard input and output so that it can log the
2588 installation process. Likewise, because these scripts
2589 may be executed with standard output redirected into a
2590 pipe for logging purposes, Perl scripts should set
2591 unbuffered output by setting <tt>$|=1</tt> so that the
2592 output is printed immediately rather than being
2597 Each script should return a zero exit status for
2598 success, or a nonzero one for failure.
2602 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2607 <list compact="compact">
2609 <p><var>new-preinst</var> <tt>install</tt></p>
2612 <p><var>new-preinst</var> <tt>install</tt>
2613 <var>old-version</var></p>
2616 <p><var>new-preinst</var> <tt>upgrade</tt>
2617 <var>old-version</var></p>
2620 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2621 <var>new-version</var>
2627 <list compact="compact">
2629 <p><var>postinst</var> <tt>configure</tt>
2630 <var>most-recently-configured-version</var></p>
2633 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2634 <var>new-version</var></p>
2637 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2638 <tt>in-favour</tt> <var>package</var>
2639 <var>new-version</var></p>
2643 <var>deconfigured's-postinst</var>
2644 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2645 <var>failed-install-package</var> <var>version</var>
2646 <tt>removing</tt> <var>conflicting-package</var>
2653 <list compact="compact">
2655 <p><var>prerm</var> <tt>remove</tt></p>
2658 <p><var>old-prerm</var> <tt>upgrade</tt>
2659 <var>new-version</var></p>
2662 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2663 <var>old-version</var></p>
2666 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2667 <tt>in-favour</tt> <var>package</var>
2668 <var>new-version</var></p>
2672 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2673 <tt>in-favour</tt> <var>package-being-installed</var>
2674 <var>version</var> <tt>removing</tt>
2675 <var>conflicting-package</var>
2682 <list compact="compact">
2684 <p><var>postrm</var> <tt>remove</tt></p>
2687 <p><var>postrm</var> <tt>purge</tt></p>
2691 <var>old-postrm</var> <tt>upgrade</tt>
2692 <var>new-version</var></p>
2695 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2696 <var>old-version</var></p>
2699 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2702 <p><var>new-postrm</var> <tt>abort-install</tt>
2703 <var>old-version</var></p>
2706 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2707 <var>old-version</var></p>
2711 <var>disappearer's-postrm</var> <tt>disappear</tt>
2712 <var>overwriter</var>
2713 <var>overwriter-version</var></p></item>
2718 <sect id="unpackphase"><heading>Details of unpack phase of
2719 installation or upgrade
2723 The procedure on installation/upgrade/overwrite/disappear
2724 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2725 stage of <tt>dpkg --install</tt>) is as follows. In each
2726 case, if a major error occurs (unless listed below) the
2727 actions are, in general, run backwards - this means that the
2728 maintainer scripts are run with different arguments in
2729 reverse order. These are the `error unwind' calls listed
2737 <p>If a version of the package is already
2739 <example compact="compact">
2740 <var>old-prerm</var> upgrade <var>new-version</var>
2745 If the script runs but exits with a non-zero
2746 exit status, <prgn>dpkg</prgn> will attempt:
2747 <example compact="compact">
2748 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2750 Error unwind, for both the above cases:
2751 <example compact="compact">
2752 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2760 <p>If a `conflicting' package is being removed at the same time:
2764 If any packages depended on that conflicting
2765 package and <tt>--auto-deconfigure</tt> is
2766 specified, call, for each such package:
2767 <example compact="compact">
2768 <var>deconfigured's-prerm</var> deconfigure \
2769 in-favour <var>package-being-installed</var> <var>version</var> \
2770 removing <var>conflicting-package</var> <var>version</var>
2773 <example compact="compact">
2774 <var>deconfigured's-postinst</var> abort-deconfigure \
2775 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2776 removing <var>conflicting-package</var> <var>version</var>
2778 The deconfigured packages are marked as
2779 requiring configuration, so that if
2780 <tt>--install</tt> is used they will be
2781 configured again if possible.</p>
2784 <p>To prepare for removal of the conflicting package, call:
2785 <example compact="compact">
2786 <var>conflictor's-prerm</var> remove \
2787 in-favour <var>package</var> <var>new-version</var>
2790 <example compact="compact">
2791 <var>conflictor's-postinst</var> abort-remove \
2792 in-favour <var>package</var> <var>new-version</var>
2803 <p>If the package is being upgraded, call:
2804 <example compact="compact">
2805 <var>new-preinst</var> upgrade <var>old-version</var>
2810 Otherwise, if the package had some configuration
2811 files from a previous version installed (i.e., it
2812 is in the `configuration files only' state):
2813 <example compact="compact">
2814 <var>new-preinst</var> install <var>old-version</var>
2818 <p>Otherwise (i.e., the package was completely purged):
2819 <example compact="compact">
2820 <var>new-preinst</var> install
2822 Error unwind actions, respectively:
2823 <example compact="compact">
2824 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2825 <var>new-postrm</var> abort-install <var>old-version</var>
2826 <var>new-postrm</var> abort-install
2836 The new package's files are unpacked, overwriting any
2837 that may be on the system already, for example any
2838 from the old version of the same package or from
2839 another package. Backups of the old files are kept
2840 temporarily, and if anything goes wrong the package
2841 management system will attempt to put them back as
2842 part of the error unwind.
2846 It is an error for a package to contains files which
2847 are on the system in another package, unless
2848 <tt>Replaces</tt> is used (see <ref id="replaces">).
2850 The following paragraph is not currently the case:
2851 Currently the <tt>- - force-overwrite</tt> flag is
2852 enabled, downgrading it to a warning, but this may not
2858 It is a more serious error for a package to contain a
2859 plain file or other kind of non-directory where another
2860 package has a directory (again, unless
2861 <tt>Replaces</tt> is used). This error can be
2862 overridden if desired using
2863 <tt>--force-overwrite-dir</tt>, but this is not
2868 Packages which overwrite each other's files produce
2869 behavior which, though deterministic, is hard for the
2870 system administrator to understand. It can easily
2871 lead to `missing' programs if, for example, a package
2872 is installed which overwrites a file from another
2873 package, and is then removed again.
2876 Part of the problem is due to what is arguably a
2877 bug in <prgn>dpkg</prgn>.
2883 A directory will never be replaced by a symbolic link
2884 to a directory or vice versa; instead, the existing
2885 state (symlink or not) will be left alone and
2886 <prgn>dpkg</prgn> will follow the symlink if there is
2894 <p>If the package is being upgraded, call
2895 <example compact="compact">
2896 <var>old-postrm</var> upgrade <var>new-version</var>
2900 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2901 <example compact="compact">
2902 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2904 Error unwind, for both cases:
2905 <example compact="compact">
2906 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2912 This is the point of no return - if
2913 <prgn>dpkg</prgn> gets this far, it won't back off
2914 past this point if an error occurs. This will
2915 leave the package in a fairly bad state, which
2916 will require a successful re-installation to clear
2917 up, but it's when <prgn>dpkg</prgn> starts doing
2918 things that are irreversible.
2923 Any files which were in the old version of the package
2924 but not in the new are removed.</p>
2927 <p>The new file list replaces the old.</p>
2930 <p>The new maintainer scripts replace the old.</p>
2934 <p>Any packages all of whose files have been overwritten during the
2935 installation, and which aren't required for
2936 dependencies, are considered to have been removed.
2937 For each such package
2940 <p><prgn>dpkg</prgn> calls:
2941 <example compact="compact">
2942 <var>disappearer's-postrm</var> disappear \
2943 <var>overwriter</var> <var>overwriter-version</var>
2948 <p>The package's maintainer scripts are removed.
2953 It is noted in the status database as being in a
2954 sane state, namely not installed (any conffiles
2955 it may have are ignored, rather than being
2956 removed by <prgn>dpkg</prgn>). Note that
2957 disappearing packages do not have their prerm
2958 called, because <prgn>dpkg</prgn> doesn't know
2959 in advance that the package is going to
2968 Any files in the package we're unpacking that are also
2969 listed in the file lists of other packages are removed
2970 from those lists. (This will lobotomize the file list
2971 of the `conflicting' package if there is one.)
2976 The backup files made during installation, above, are
2983 The new package's status is now sane, and recorded as
2988 Here is another point of no return - if the
2989 conflicting package's removal fails we do not unwind
2990 the rest of the installation; the conflicting package
2991 is left in a half-removed limbo.
2997 If there was a conflicting package we go and do the
2998 removal actions (described below), starting with the
2999 removal of the conflicting package's files (any that
3000 are also in the package being installed have already
3001 been removed from the conflicting package's file list,
3002 and so do not get removed now).
3009 <sect><heading>Details of configuration</heading>
3012 When we configure a package (this happens with <tt>dpkg
3013 --install</tt>, or with <tt>--configure</tt>), we first
3014 update any <tt>conffile</tt>s and then call:
3015 <example compact="compact">
3016 <var>postinst</var> configure <var>most-recently-configured-version</var>
3021 No attempt is made to unwind after errors during
3026 If there is no most recently configured version
3027 <prgn>dpkg</prgn> will pass a null argument; older versions
3028 of dpkg may pass <tt><unknown></tt> (including the
3029 angle brackets) in this case. Even older ones do not pass a
3030 second argument at all, under any circumstances.
3034 <sect><heading>Details of removal and/or configuration purging
3041 <example compact="compact">
3042 <var>prerm</var> remove
3048 The package's files are removed (except <tt>conffile</tt>s).
3053 <example compact="compact">
3054 <var>postrm</var> remove
3060 All the maintainer scripts except the <prgn>postrm</prgn>
3065 If we aren't purging the package we stop here. Note
3066 that packages which have no <prgn>postrm</prgn> and no
3067 <tt>conffile</tt>s are automatically purged when
3068 removed, as there is no difference except for the
3069 <prgn>dpkg</prgn> status.</p>
3073 The conffiles and any backup files (<tt>~</tt>-files,
3074 <tt>#*#</tt> files, <tt>%</tt>-files,
3075 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3079 <example compact="compact">
3080 <var>postrm</var> purge
3085 <p>The package's file list is removed.</p>
3088 No attempt is made to unwind after errors during
3095 <chapt id="relationships"><heading>Declaring relationships between
3099 Packages can declare in their control file that they have
3100 certain relationships to other packages - for example, that
3101 they may not be installed at the same time as certain other
3102 packages, and/or that they depend on the presence of others,
3103 or that they should overwrite files in certain other packages
3108 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3109 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3110 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3111 control file fields.
3115 Source packages may declare relationships to binary packages,
3116 saying that they require certain binary packages to be
3117 installed or absent at the time of building the package.
3121 This is done using the <tt>Build-Depends</tt>,
3122 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3123 <tt>Build-Conflicts-Indep</tt> control file fields.
3126 <sect id="depsyntax"><heading>Syntax of relationship fields
3130 These fields all have a uniform syntax. They are a list of
3131 package names separated by commas.
3135 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3136 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3137 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3138 control file fields of the package, which declare
3139 dependencies on other packages, the package names listed may
3140 also include lists of alternative package names, separated
3141 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3142 if any one of the alternative packages is installed, that
3143 part of the dependency is considered to be satisfied.
3147 All of the fields except for <tt>Provides</tt> may restrict
3148 their applicability to particular versions of each named
3149 package. This is done in parentheses after each individual
3150 package name; the parentheses should contain a relation from
3151 the list below followed by a version number, in the format
3152 described in <ref id="versions">.
3156 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3157 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3158 strictly earlier, earlier or equal, exactly equal, later or
3159 equal and strictly later, respectively. The deprecated
3160 forms <tt><</tt> and <tt>></tt> were used to mean
3161 earlier/later or equal, rather than strictly earlier/later,
3162 so they should not appear in new packages (though
3163 <prgn>dpkg</prgn> still supports them).
3167 Whitespace may appear at any point in the version
3168 specification subject to the rules in <ref
3169 id="controlsyntax">, and must appear where it's necessary to
3170 disambiguate; it is not otherwise significant. For
3171 consistency and in case of future changes to
3172 <prgn>dpkg</prgn> it is recommended that a single space be
3173 used after a version relationship and before a version
3174 number; it is also conventional to put a single space after
3175 each comma, on either side of each vertical bar, and before
3176 each open parenthesis.
3180 For example, a list of dependencies might appear as:
3181 <example compact="compact">
3184 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3189 All fields that specify build-time relationships
3190 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3191 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3192 may be restricted to a certain set of architectures. This
3193 is indicated in brackets after each individual package name and
3194 the optional version specification. The brackets enclose a
3195 list of Debian architecture names separated by whitespace.
3196 Exclamation marks may be prepended to each of the names.
3197 (It is not permitted for some names to be prepended with
3198 exclamation marks and others not.) If the current Debian
3199 host architecture is not in this list and there are no
3200 exclamation marks in the list, or it is in the list with a
3201 prepended exclamation mark, the package name and the
3202 associated version specification are ignored completely for
3203 the purposes of defining the relationships.
3208 <example compact="compact">
3210 Build-Depends-Indep: texinfo
3211 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3212 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3217 Note that the binary package relationship fields such as
3218 <tt>Depends</tt> appear in one of the binary package
3219 sections of the control file, whereas the build-time
3220 relationships such as <tt>Build-Depends</tt> appear in the
3221 source package section of the control file (which is the
3227 <heading>Binary Dependencies - <tt>Depends</tt>,
3228 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3229 <tt>Pre-Depends</tt>
3233 These five fields are used to declare a dependency
3234 relationship by one package on another. Except for
3235 <tt>Enhances</tt>, they appear in the depending (binary)
3236 package's control file. (<tt>Enhances</tt> appears in the
3237 recommending package's control file.)
3241 A <tt>Depends</tt> field takes effect <em>only</em> when a
3242 package is to be configured. It does not prevent a package
3243 being on the system in an unconfigured state while its
3244 dependencies are unsatisfied, and it is possible to replace
3245 a package whose dependencies are satisfied and which is
3246 properly installed with a different version whose
3247 dependencies are not and cannot be satisfied; when this is
3248 done the depending package will be left unconfigured (since
3249 attempts to configure it will give errors) and will not
3250 function properly. If it is necessary, a
3251 <tt>Pre-Depends</tt> field can be used, which has a partial
3252 effect even when a package is being unpacked, as explained
3253 in detail below. (The other three dependency fields,
3254 <tt>Recommends</tt>, <tt>Suggests</tt> and
3255 <tt>Enhances</tt>, are only used by the various front-ends
3256 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3260 For this reason packages in an installation run are usually
3261 all unpacked first and all configured later; this gives
3262 later versions of packages with dependencies on later
3263 versions of other packages the opportunity to have their
3264 dependencies satisfied.
3268 The <tt>Depends</tt> field thus allows package maintainers
3269 to impose an order in which packages should be configured.
3273 The meaning of the five dependency fields is as follows:
3275 <tag><tt>Depends</tt></tag>
3279 This declares an absolute dependency. A package will
3280 not be configured unless all of the packages listed in
3281 its <tt>Depends</tt> field have been correctly
3286 The <tt>Depends</tt> field should be used if the
3287 depended-on package is required for the depending
3288 package to provide a significant amount of
3292 The <tt>Depends</tt> field should also be used if the
3293 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3294 <prgn>postrm</prgn> scripts require the package to be
3295 present in order to run. Note, however, that the
3296 <prgn>postrm</prgn> cannot rely on any non-essential
3297 packages to be present during the <tt>purge</tt>
3301 <tag><tt>Recommends</tt></tag>
3303 <p>This declares a strong, but not absolute, dependency.
3307 The <tt>Recommends</tt> field should list packages
3308 that would be found together with this one in all but
3309 unusual installations.</p>
3312 <tag><tt>Suggests</tt></tag>
3316 This is used to declare that one package may be more
3317 useful with one or more others. Using this field
3318 tells the packaging system and the user that the
3319 listed packages are related to this one and can
3320 perhaps enhance its usefulness, but that installing
3321 this one without them is perfectly reasonable.
3325 <tag><tt>Enhances</tt></tag>
3328 This field is similar to Suggests but works in the
3329 opposite direction. It is used to declare that a
3330 package can enhance the functionality of another
3335 <tag><tt>Pre-Depends</tt></tag>
3339 This field is like <tt>Depends</tt>, except that it
3340 also forces <prgn>dpkg</prgn> to complete installation
3341 of the packages named before even starting the
3342 installation of the package which declares the
3343 pre-dependency, as follows:
3347 When a package declaring a pre-dependency is about to
3348 be <em>unpacked</em> the pre-dependency can be
3349 satisfied if the depended-on package is either fully
3350 configured, <em>or even if</em> the depended-on
3351 package(s) are only unpacked or half-configured,
3352 provided that they have been configured correctly at
3353 some point in the past (and not removed or partially
3354 removed since). In this case, both the
3355 previously-configured and currently unpacked or
3356 half-configured versions must satisfy any version
3357 clause in the <tt>Pre-Depends</tt> field.
3361 When the package declaring a pre-dependency is about
3362 to be <em>configured</em>, the pre-dependency will be
3363 treated as a normal <tt>Depends</tt>, that is, it will
3364 be considered satisfied only if the depended-on
3365 package has been correctly configured.
3369 <tt>Pre-Depends</tt> should be used sparingly,
3370 preferably only by packages whose premature upgrade or
3371 installation would hamper the ability of the system to
3372 continue with any upgrade that might be in progress.
3376 <tt>Pre-Depends</tt> are also required if the
3377 <prgn>preinst</prgn> script depends on the named
3378 package. It is best to avoid this situation if
3384 When selecting which level of dependency to use you should
3385 consider how important the depended-on package is to the
3386 functionality of the one declaring the dependency. Some
3387 packages are composed of components of varying degrees of
3388 importance. Such a package should list using
3389 <tt>Depends</tt> the package(s) which are required by the
3390 more important components. The other components'
3391 requirements may be mentioned as Suggestions or
3392 Recommendations, as appropriate to the components' relative
3397 <sect id="conflicts"><heading>Conflicting binary packages -
3398 <tt>Conflicts</tt></heading>
3401 When one binary package declares a conflict with another
3402 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3403 refuse to allow them to be installed on the system at the
3408 If one package is to be installed, the other must be removed
3409 first - if the package being installed is marked as
3410 replacing (see <ref id="replaces">) the one on the system,
3411 or the one on the system is marked as deselected, or both
3412 packages are marked <tt>Essential</tt>, then
3413 <prgn>dpkg</prgn> will automatically remove the package
3414 which is causing the conflict, otherwise it will halt the
3415 installation of the new package with an error. This
3416 mechanism is specifically designed to produce an error when
3417 the installed package is <tt>Essential</tt>, but the new
3422 A package will not cause a conflict merely because its
3423 configuration files are still installed; it must be at least
3428 A special exception is made for packages which declare a
3429 conflict with their own package name, or with a virtual
3430 package which they provide (see below): this does not
3431 prevent their installation, and allows a package to conflict
3432 with others providing a replacement for it. You use this
3433 feature when you want the package in question to be the only
3434 package providing some feature.
3438 A <tt>Conflicts</tt> entry should almost never have an
3439 `earlier than' version clause. This would prevent
3440 <prgn>dpkg</prgn> from upgrading or installing the package
3441 which declared such a conflict until the upgrade or removal
3442 of the conflicted-with package had been completed.
3446 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3450 As well as the names of actual (`concrete') packages, the
3451 package relationship fields <tt>Depends</tt>,
3452 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3453 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3454 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3455 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3456 may mention `virtual packages'.
3460 A <em>virtual package</em> is one which appears in the
3461 <tt>Provides</tt> control file field of another package.
3462 The effect is as if the package(s) which provide a
3463 particular virtual package name had been listed by name
3464 everywhere the virtual package name appears.
3468 If there are both a real and a virtual package of the same
3469 name then the dependency may be satisfied (or the conflict
3470 caused) by either the real package or any of the virtual
3471 packages which provide it. This is so that, for example,
3473 <example compact="compact">
3477 and someone else releases an enhanced version of the
3478 <tt>bar</tt> package (for example, a non-US variant), they
3480 <example compact="compact">
3484 and the <tt>bar-plus</tt> package will now also satisfy the
3485 dependency for the <tt>foo</tt> package.
3489 If a dependency or a conflict has a version number attached
3490 then only real packages will be considered to see whether
3491 the relationship is satisfied (or the prohibition violated,
3492 for a conflict) - it is assumed that a real package which
3493 provides the virtual package is not of the `right' version.
3494 So, a <tt>Provides</tt> field may not contain version
3495 numbers, and the version number of the concrete package
3496 which provides a particular virtual package will not be
3497 looked at when considering a dependency on or conflict with
3498 the virtual package name.
3502 It is likely that the ability will be added in a future
3503 release of <prgn>dpkg</prgn> to specify a version number for
3504 each virtual package it provides. This feature is not yet
3505 present, however, and is expected to be used only
3510 If you want to specify which of a set of real packages
3511 should be the default to satisfy a particular dependency on
3512 a virtual package, you should list the real package as an
3513 alternative before the virtual one.
3518 <sect id="replaces"><heading>Overwriting files and replacing
3519 packages - <tt>Replaces</tt></heading>
3522 The <tt>Replaces</tt> control file field has two distinct
3523 purposes, which come into play in different situations.
3526 <sect1><heading>Overwriting files in other packages</heading>
3529 Firstly, as mentioned before, it is usually an error for a
3530 package to contain files which are on the system in
3535 However, if the overwriting package declares that it
3536 <tt>Replaces</tt> the one containing the file being
3537 overwritten, then <prgn>dpkg</prgn> will replace the file
3538 from the old package with that from the new. The file
3539 will no longer be listed as `owned' by the old package.
3543 If a package is completely replaced in this way, so that
3544 <prgn>dpkg</prgn> does not know of any files it still
3545 contains, it is considered to have `disappeared'. It will
3546 be marked as not wanted on the system (selected for
3547 removal) and not installed. Any <tt>conffile</tt>s
3548 details noted for the package will be ignored, as they
3549 will have been taken over by the overwriting package. The
3550 package's <prgn>postrm</prgn> script will be run with a
3551 special argument to allow the package to do any final
3552 cleanup required. See <ref id="mscriptsinstact">.
3556 If an installed package, <tt>foo</tt> say, declares that
3557 it replaces another, <tt>bar</tt>, and an attempt is made
3558 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3559 files in the <tt>bar</tt> package which would overwrite
3560 those already present in <tt>foo</tt>. This is so that
3561 you can install an older version of a package without
3566 For this usage of <tt>Replaces</tt>, virtual packages (see
3567 <ref id="virtual">) are not considered when looking at a
3568 <tt>Replaces</tt> field - the packages declared as being
3569 replaced must be mentioned by their real names.
3573 Furthermore, this usage of <tt>Replaces</tt> only takes
3574 effect when both packages are at least partially on the
3575 system at once, so that it can only happen if they do not
3576 conflict or if the conflict has been overridden.
3581 <sect1><heading>Replacing whole packages, forcing their
3585 Secondly, <tt>Replaces</tt> allows the packaging system to
3586 resolve which package should be removed when there is a
3587 conflict - see <ref id="conflicts">. This usage only
3588 takes effect when the two packages <em>do</em> conflict,
3589 so that the two usages of this field do not interfere with
3594 In this situation, the package declared as being replaced
3595 can be a virtual package, so for example, all mail
3596 transport agents (MTAs) would have the following fields in
3597 their control files:
3598 <example compact="compact">
3599 Provides: mail-transport-agent
3600 Conflicts: mail-transport-agent
3601 Replaces: mail-transport-agent
3603 ensuring that only one MTA can be installed at any one
3608 <sect><heading>Relationships between source and binary packages -
3609 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3610 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3614 A source package may declare a dependency or a conflict on a
3615 binary package, indicating which packages are required to be
3616 present on the system in order to build the binary packages
3617 from the source package. This is done with the control file
3618 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3619 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3620 The dependencies and conflicts they define must be satisfied
3621 (as defined earlier for binary packages) in order to invoke
3622 the targets in <tt>debian/rules</tt>, as follows:
3625 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3628 The <tt>Build-Depends</tt> and
3629 <tt>Build-Conflicts</tt> fields must be satisfied when
3630 any of the following targets is invoked:
3631 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3632 and <tt>binary-indep</tt>.
3635 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3638 The <tt>Build-Depends-Indep</tt> and
3639 <tt>Build-Conflicts-Indep</tt> fields must be
3640 satisfied when any of the following targets is
3641 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3652 <chapt id="conffiles"><heading>Configuration file handling
3656 This chapter has been superseded by <ref id="config files">.
3660 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3663 Packages containing shared libraries must be constructed with
3664 a little care to make sure that the shared library is always
3665 available. This is especially important for packages whose
3666 shared libraries are vitally important, such as the C library
3667 (currently <tt>libc6</tt>).
3671 Firstly, the package should install the shared libraries under
3672 their normal names. For example, the <tt>libgdbmg1</tt>
3673 package should install <tt>libgdbm.so.1.7.3</tt> as
3674 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3675 renamed or re-linked by any <prgn>prerm</prgn> or
3676 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3677 of renaming things safely without affecting running programs,
3678 and attempts to interfere with this are likely to lead to
3683 Secondly, the package should include the symbolic link that
3684 <prgn>ldconfig</prgn> would create for the shared libraries.
3685 For example, the <prgn>libgdbmg1</prgn> package should include
3686 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3687 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3688 linker (for example <prgn>ld.so</prgn> or
3689 <prgn>ld-linux.so.*</prgn>) can find the library between the
3690 time that <prgn>dpkg</prgn> installs it and the time that
3691 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3695 The package management system requires the library to be
3696 placed before the symbolic link pointing to it in the
3697 <tt>.deb</tt> file. This is so that when
3698 <prgn>dpkg</prgn> comes to install the symlink
3699 (overwriting the previous symlink pointing at an older
3700 version of the library), the new shared library is already
3701 in place. In the past, this was achieved by creating the
3702 library in the temporary packaging directory before
3703 creating the symlink. Unfortunately, this was not always
3704 effective, since the building of the tar file in the
3705 <tt>.deb</tt> depended on the behavior of the underlying
3706 file system. Some file systems (such as reiserfs) reorder
3707 the files so that the order of creation is forgotten.
3708 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3709 will reorder the files itself as necessary when building a
3710 package. Thus it is no longer important to concern
3711 oneself with the order of file creation.
3717 Thirdly, the associated development package should contain a
3718 symlink for the shared library without a version number. For
3719 example, the <tt>libgdbmg1-dev</tt> package should include a
3720 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3721 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3722 linker (<prgn>ld</prgn>) when compiling packages, as it will
3723 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3727 Any package installing shared libraries in one of the default
3728 library directories of the dynamic linker (which are currently
3729 <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
3730 listed in <tt>/etc/ld.so.conf</tt>
3734 <list compact="compact">
3735 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3736 <item><p>/usr/local/lib</p></item>
3737 <item><p>/usr/lib/libc5-compat</p></item>
3738 <item><p>/lib/libc5-compat</p></item>
3739 <item><p>/usr/X11R6/lib</p></item>
3743 must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3744 script if and only if the first argument is <tt>configure</tt>
3745 and should call it in the <prgn>postrm</prgn> script if the
3746 first argument is <tt>remove</tt>.
3750 However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
3751 <em>must not</em> call <prgn>ldconfig</prgn> in the case where
3752 the package is being upgraded (see <ref id="unpackphase"> for
3753 details), as <prgn>ldconfig</prgn> will see the temporary
3754 names that <prgn>dpkg</prgn> uses for the files while it is
3755 installing them and will make the shared library links point
3756 to them, just before <prgn>dpkg</prgn> continues the
3757 installation and renames the temporary files!
3761 <heading>Handling shared library dependencies - the
3762 <tt>shlibs</tt> system</heading>
3765 If a package contains a binary or library which links to a
3766 shared library, we must ensure that when the package is
3767 installed on the system, all of the libraries needed are
3768 also installed. This requirement led to the creation of the
3769 <tt>shlibs</tt> system, which is very simple in its design:
3770 any package which <em>provides</em> a shared library also
3771 provides information on the package dependencies required to
3772 ensure the presence of this library, and any package which
3773 <em>uses</em> a shared library uses this information to
3774 determine the dependencies it requires. The files which
3775 contain the mapping from shared libraries to the necessary
3776 dependency information are called <tt>shlibs</tt> files.
3780 Thus, when a package is built which contains any shared
3781 libraries, it must provide a <tt>shlibs</tt> file for other
3782 packages to use, and when a package is built which contains
3783 any shared libraries or compiled binaries, it must run
3784 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3785 libraries used and hence the dependencies needed by this
3789 In the past, the shared libraries linked to were
3790 determined by calling <prgn>ldd</prgn>, but now
3791 <prgn>objdump</prgn> to do this. The only change this
3792 makes to package building is that
3793 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3794 libraries, whereas in the past this was unnecessary.
3795 The rest of this footnote explains the advantage that
3800 We say that a binary <tt>foo</tt> <em>directly</em> uses
3801 a library <tt>libbar</tt> if it is explicitly linked
3802 with that library (that is, it uses the flag
3803 <tt>-lbar</tt> during the linking stage). Other
3804 libraries that are needed by <tt>libbar</tt> are linked
3805 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3806 linker will load them automatically when it loads
3807 <tt>libbar</tt>. A package should needs to depend on
3808 the libraries it directly uses, and the dependencies for
3809 those libraries should automatically pull in the other
3814 Unfortunately, the <prgn>ldd</prgn> program shows both
3815 the directly and indirectly used libraries, meaning that
3816 the dependencies determined included both direct and
3817 indirect dependencies. The use of <prgn>objdump</prgn>
3818 avoids this problem by determining only the directly
3823 A good example of where this helps is the following. We
3824 could update <tt>libimlib</tt> with a new version that
3825 supports a new graphics format called dgf (but retaining
3826 the same major version number). If we used the old
3827 <prgn>ldd</prgn> method, every package that uses
3828 <tt>libimlib</tt> would need to be recompiled so it
3829 would also depend on <tt>libdgf</tt> or it wouldn't run
3830 due to missing symbols. However with the new system,
3831 packages using <tt>libimlib</tt> can rely on
3832 <tt>libimlib</tt> itself having the dependency on
3833 <tt>libdgf</tt> and so they would not need rebuilding.
3839 In the following sections, we will first describe where the
3840 various <tt>shlibs</tt> files are to be found, then how to
3841 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3842 <tt>shlibs</tt> file format and how to create them if your
3843 package contains a shared library.
3847 <sect><heading>The <tt>shlibs</tt> files present on the system
3851 There are several places where <tt>shlibs</tt> files are
3852 found. The following list gives them in the order in which
3853 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3854 one which gives the required information is used.)
3860 <p><tt>debian/shlibs.local</tt></p>
3862 This lists overrides for this package. Its use is
3863 described below (see <ref id="shlibslocal">).
3868 <p><tt>/etc/dpkg/shlibs.override</tt></p>
3870 This lists global overrides. This list is normally
3871 empty. It is maintained by the local system
3877 <p><tt>DEBIAN/shlibs</tt> files in the `build directory'</p>
3879 When packages are being built, any
3880 <tt>debian/shlibs</tt> files are copied into the
3881 control file area of the temporary build directory and
3882 given the name <tt>shlibs</tt>. These files give
3883 details of any shared libraries included in the
3887 An example may help here. Let us say that the
3888 source package <tt>foo</tt> generates two binary
3889 packages, <tt>libfoo2</tt> and
3890 <tt>foo-runtime</tt>. When building the binary
3891 packages, the two packages are created in the
3892 directories <tt>debian/libfoo2</tt> and
3893 <tt>debian/foo-runtime</tt> respectively.
3894 (<tt>debian/tmp</tt> could be used instead of one
3895 of these.) Since <tt>libfoo2</tt> provides the
3896 <tt>libfoo</tt> shared library, it will require a
3897 <tt>shlibs</tt> file, which will be installed in
3898 <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
3900 <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>. Then
3901 when <prgn>dpkg-shlibdeps</prgn> is run on the
3903 <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
3905 <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
3906 determine whether <tt>foo-prog</tt>'s library
3907 dependencies are satisfied by any of the libraries
3908 provided by <tt>libfoo2</tt>. For this reason,
3909 <prgn>dpkg-shlibdeps</prgn> must only be run once
3910 all of the individual binary packages'
3911 <tt>shlibs</tt> files have been installed into the
3919 <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p>
3921 These are the <tt>shlibs</tt> files corresponding to
3922 all of the packages installed on the system, and are
3923 maintained by the relevant package maintainers.
3928 <p><tt>/etc/dpkg/shlibs.default</tt></p>
3930 This file lists any shared libraries whose packages
3931 have failed to provide correct <tt>shlibs</tt> files.
3932 It was used when the <tt>shlibs</tt> setup was first
3933 introduced, but it is now normally empty. It is
3934 maintained by the <tt>dpkg</tt> maintainer.
3942 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
3943 <tt>shlibs</tt> files</heading>
3946 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3947 <tt>debian/rules</tt> file. If your package contains only
3948 compiled binaries and libraries (but no scripts), you can
3949 use a command such as:
3950 <example compact="compact">
3951 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
3952 debian/tmp/usr/lib/*
3954 Otherwise, you will need to explicitly list the compiled
3955 binaries and libraries.
3958 If you are using <tt>debhelper</tt>, the
3959 <prgn>dh_shlibdeps</prgn> program will do this work for
3960 you. It will also correctly handle multi-binary
3967 This command puts the dependency information into the
3968 <tt>debian/substvars</tt> file, which is then used by
3969 <prgn>dpkg-gencontrol</prgn>. You will need to place a
3970 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
3971 field in the control file for this to work.
3975 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3976 done. If it does complain you might need to create your own
3977 <tt>debian/shlibs.local</tt> file, as explained below (see
3978 <ref id="shlibslocal">).
3982 If you have multiple binary packages, you will need to call
3983 <prgn>dpkg-shlibdeps</prgn> on each one which contains
3984 compiled libraries or binaries. In such a case, you will
3985 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
3986 utilities to specify a different <tt>substvars</tt> file.
3987 For more details on this and other options, see <manref
3988 name="dpkg-shlibdeps" section="1">.
3992 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3996 Each <tt>shlibs</tt> file has the same format. Lines
3997 beginning with <tt>#</tt> are considered to be commments and
3998 are ignored. Each line is of the form:
3999 <example compact="compact">
4000 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4005 We will explain this by reference to the example of the
4006 <tt>zlib1g</tt> package, which (at the time of writing)
4007 installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
4011 <var>library-name</var> is the name of the shared library,
4012 in this case <tt>libz</tt>. (This must match the name part
4013 of the soname, see below.)
4017 <var>soname-version-number</var> is the version part of the
4018 soname of the library. The soname is the thing that must
4019 exactly match for the library to be recognized by the
4020 dynamic linker, and is usually of the form
4021 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4022 example, <tt>libz.so.1</tt>.
4025 This can be determined using the command
4026 <example compact="compact">
4027 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4031 The version part is the part which comes after
4032 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4036 <var>dependencies</var> has the same syntax as a dependency
4037 field in a binary package control file. It should give
4038 details of which packages are required to satisfy a binary
4039 built against the version of the library contained in the
4040 package. See <ref id="depsyntax"> for details.
4044 In our example, if the first version of the <tt>zlib1g</tt>
4045 package which contained a minor number of at least
4046 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4047 <tt>shlibs</tt> entry for this library could say:
4048 <example compact="compact">
4049 libz 1 zlib1g (>= 1:1.1.3)
4051 The version-specific dependency is to avoid warnings from
4052 the dynamic linker about using older shared libraries with
4058 <heading>Providing a <tt>shlibs</tt> file</heading>
4061 If your package provides a shared library, you should create
4062 a <tt>shlibs</tt> file following the format described above.
4063 It is usual to call this file <tt>debian/shlibs</tt> (but if
4064 you have multiple binary packages, you might want to call it
4065 <tt>debian/shlibs.<var>package</var></tt> instead). Then
4066 let <tt>debian/rules</tt> install it in the control area:
4067 <example compact="compact">
4068 install -m644 debian/shlibs debian/tmp/DEBIAN
4070 or, in the case of a multi-binary package:
4071 <example compact="compact">
4072 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4074 An alternative way of doing this is to create the
4075 <tt>shlibs</tt> file in the control area directly from
4076 <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
4080 This is what <prgn>dh_makeshlibs</prgn> in the
4081 <tt>debhelper</tt> suite does.
4084 since the <tt>debian/shlibs</tt> file itself is ignored by
4085 <prgn>dpkg-shlibdeps</prgn>.
4089 As <prgn>dpkg-shlibdeps</prgn> reads the
4090 <tt>DEBIAN/shlibs</tt> files in all of the binary packages
4091 being built from this source package, all of the
4092 <tt>DEBIAN/shlibs</tt> files should be installed before
4093 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4098 <sect id="shlibslocal">
4099 <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
4102 This file is intended only as a <em>temporary</em> fix if
4103 your binaries or libraries depend on a library whose package
4104 does not yet provide a correct <tt>shlibs</tt> file.
4108 We will assume that you are trying to package a binary
4109 <tt>foo</tt>. When you try running
4110 <prgn>dpkg-shlibdeps</prgn> you get the following error
4111 message (<tt>-O</tt> displays the dependency information on
4112 <tt>stdout</tt> instead of writing it to
4113 <tt>debian/substvars</tt>, and the lines have been wrapped
4114 for ease of reading):
4115 <example compact="compact">
4116 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4117 dpkg-shlibdeps: warning: unable to find dependency
4118 information for shared library libbar (soname 1,
4119 path /usr/lib/libbar.so.1, dependency field Depends)
4120 shlibs:Depends=libc6 (>= 2.2.2-2)
4122 You can then run <prgn>ldd</prgn> on the binary to find the
4123 full location of the library concerned:
4124 <example compact="compact">
4126 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4127 libc.so.6 => /lib/libc.so.6 (0x40032000)
4128 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4130 So the <prgn>foo</prgn> binary depends on the
4131 <prgn>libbar</prgn> shared library, but no package seems to
4132 provide a <tt>*.shlibs</tt> file handling
4133 <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>. Let's
4134 determine the package responsible:
4135 <example compact="compact">
4136 $ dpkg -S /usr/lib/libbar.so.1
4137 bar1: /usr/lib/libbar.so.1
4138 $ dpkg -s bar1 | grep Version
4141 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4142 is the one we are using. Now we can file a bug against the
4143 <tt>bar1</tt> package and create our own
4144 <tt>debian/shlibs.local</tt> to locally fix the problem.
4145 Including the following line into your
4146 <tt>debian/shlibs.local</tt> file:
4147 <example compact="compact">
4148 libbar 1 bar1 (>= 1.0-1)
4150 should allow the package build to work.
4154 As soon as the maintainer of <tt>bar1</tt> provides a
4155 correct <tt>shlibs</tt> file, you should remove this line
4156 from your <tt>debian/shlibs.local</tt> file. (You should
4157 probably also then have a versioned <tt>Build-Depends</tt>
4158 on <tt>bar1</tt> to help ensure that others do not have the
4159 same problem building your package.)
4164 <chapt id="opersys"><heading>The Operating System</heading>
4167 <heading>Filesystem hierarchy</heading>
4171 <heading>Filesystem Structure</heading>
4174 The location of all installed files and directories must
4175 comply with the Filesystem Hierarchy Standard (FHS),
4176 version 2.1. This can be found in the
4177 <tt>debian-policy</tt> package or on <url
4178 id="http://www.debian.org/doc/packaging-manuals/fhs"
4179 name="FHS (Debian copy)"> alongside this manual or on <url
4180 id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4181 Specific questions about following the standard may be
4182 asked on the <tt>debian-devel</tt> mailing list, or
4183 referred to Daniel Quinlan, the FHS coordinator, at
4184 <email>quinlan@pathname.com</email>.
4189 <heading>Site-specific programs</heading>
4192 As mandated by the FHS, packages must not place any
4193 files in <tt>/usr/local</tt>, either by putting them in
4194 the file system archive to be unpacked by <prgn>dpkg</prgn>
4195 or by manipulating them in their maintainer scripts.
4199 However, the package may create empty directories below
4200 <tt>/usr/local</tt> so that the system administrator knows
4201 where to place site-specific files. These directories
4202 should be removed on package removal if they are
4207 Note, that this applies only to directories <em>below</em>
4208 <tt>/usr/local</tt>, not <em>in</em> <tt>/usr/local</tt>.
4209 Packages must not create sub-directories in the directory
4210 <tt>/usr/local</tt> itself, except those listed in FHS,
4211 section 4.5. However, you may create directories below
4212 them as you wish. You must not remove any of the
4213 directories listed in 4.5, even if you created them.
4217 Since <tt>/usr/local</tt> can be mounted read-only from a
4218 remote server, these directories must be created and
4219 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4220 maintainer scripts and not be included in the
4221 <tt>.deb</tt> archive. These scripts must not fail if
4222 either of these operations fail.
4225 In the future, it may be possible to tell
4226 <prgn>dpkg</prgn> not to unpack files matching certain
4227 patterns, so that the directories can be included in
4228 the <tt>.deb</tt> packages and system administrators
4229 who do not wish these directories in
4230 <tt>/usr/local</tt> do not need to have them.)
4236 For example, the <tt>emacsen-common</tt> package could
4237 contain something like
4238 <example compact="compact">
4239 if [ ! -e /usr/local/share/emacs ]
4241 if mkdir /usr/local/share/emacs 2>/dev/null
4243 chown root:staff /usr/local/share/emacs
4244 chmod 2775 /usr/local/share/emacs
4248 in its <prgn>postinst</prgn> script, and
4249 <example compact="compact">
4250 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4251 rmdir /usr/local/share/emacs 2>/dev/null || true
4253 in the <prgn>prerm</prgn> script. (Note that this form is
4254 used to ensure that if the script is interrupted, the
4255 directory <tt>/usr/local/share/emacs</tt> will still be
4260 If you do create a directory in <tt>/usr/local</tt> for
4261 local additions to a package, you should ensure that
4262 settings in <tt>/usr/local</tt> take precedence over the
4263 equivalents in <tt>/usr</tt>.
4267 However, because <tt>/usr/local</tt> and its contents are
4268 for exclusive use of the local administrator, a package
4269 must not rely on the presence or absence of files or
4270 directories in <tt>/usr/local</tt> for normal operation.
4274 The <tt>/usr/local</tt> directory itself and all the
4275 subdirectories created by the package should (by default) have
4276 permissions 2775 (group-writable and set-group-id) and be
4277 owned by <tt>root.staff</tt>.
4282 <heading>The system-wide mail directory</heading>
4284 The system-wide mail directory is <tt>/var/mail</tt>. This
4285 directory is part of the base system and should not owned
4286 by any particular mail agents. The use of the old
4287 location <tt>/var/spool/mail</tt> is deprecated, even
4288 though the spool may still be physically located there.
4289 To maintain partial upgrade compatibility for systems
4290 which have <tt>/var/spool/mail</tt> as their physical mail
4291 spool, packages using <tt>/var/mail</tt> must depend on
4292 either <package>libc6</package> (>= 2.1.3-13), or on
4293 <package>base-files</package> (>= 2.2.0), or on later
4294 versions of either one of these packages.
4300 <heading>Users and groups</heading>
4303 <heading>Introduction</heading>
4305 The Debian system can be configured to use either plain or
4310 Some user ids (UIDs) and group ids (GIDs) are reserved
4311 globally for use by certain packages. Because some
4312 packages need to include files which are owned by these
4313 users or groups, or need the ids compiled into binaries,
4314 these ids must be used on any Debian system only for the
4315 purpose for which they are allocated. This is a serious
4316 restriction, and we should avoid getting in the way of
4317 local administration policies. In particular, many sites
4318 allocate users and/or local system groups starting at 100.
4322 Apart from this we should have dynamically allocated ids,
4323 which should by default be arranged in some sensible
4324 order, but the behavior should be configurable.
4328 Packages other than <tt>base-passwd</tt> must not modify
4329 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4330 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.
4335 <heading>UID and GID classes</heading>
4337 The UID and GID numbers are divided into classes as
4343 Globally allocated by the Debian project, the same
4344 on every Debian system. These ids will appear in
4345 the <tt>passwd</tt> and <tt>group</tt> files of all
4346 Debian systems, new ids in this range being added
4347 automatically as the <tt>base-passwd</tt> package is
4352 Packages which need a single statically allocated
4353 uid or gid should use one of these; their
4354 maintainers should ask the <tt>base-passwd</tt>
4362 Dynamically allocated system users and groups.
4363 Packages which need a user or group, but can have
4364 this user or group allocated dynamically and
4365 differently on each system, should use <tt>adduser
4366 --system</tt> to create the group and/or user.
4367 <prgn>adduser</prgn> will check for the existence of
4368 the user or group, and if necessary choose an unused
4369 id based on the ranges specified in
4370 <tt>adduser.conf</tt>.
4374 <tag>1000-29999:</tag>
4377 Dynamically allocated user accounts. By default
4378 <prgn>adduser</prgn> will choose UIDs and GIDs for
4379 user accounts in this range, though
4380 <tt>adduser.conf</tt> may be used to modify this
4385 <tag>30000-59999:</tag>
4390 <tag>60000-64999:</tag>
4393 Globally allocated by the Debian project, but only
4394 created on demand. The ids are allocated centrally
4395 and statically, but the actual accounts are only
4396 created on users' systems on demand.
4400 These ids are for packages which are obscure or
4401 which require many statically-allocated ids. These
4402 packages should check for and create the accounts in
4403 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4404 <prgn>adduser</prgn> if it has this facility) if
4405 necessary. Packages which are likely to require
4406 further allocations should have a `hole' left after
4407 them in the allocation, to give them room to
4412 <tag>65000-65533:</tag>
4420 User <tt>nobody</tt>. The corresponding gid refers
4421 to the group <tt>nogroup</tt>.
4428 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4429 not</em> be used, because it is the error return
4438 <sect id="sysvinit">
4439 <heading>System run levels and <tt>init.d</tt> scripts</heading>
4441 <sect1 id="/etc/init.d">
4442 <heading>Introduction</heading>
4445 The <tt>/etc/init.d</tt> directory contains the scripts
4446 executed by <prgn>init</prgn> at boot time and when the
4447 init state (or `runlevel') is changed (see <manref
4448 name="init" section="8">).
4452 There are at least two different, yet functionally
4453 equivalent, ways of handling these scripts. For the sake
4454 of simplicity, this document describes only the symbolic
4455 link method. However, it must not be assumed by maintainer
4456 scripts that this method is being used, and any automated
4457 manipulation of the various runlevel behaviours by
4458 maintainer scripts must be performed using
4459 <prgn>update-rc.d</prgn> as described below and not by
4460 manually installing or removing symlinks. For information
4461 on the implementation details of the other method,
4462 implemented in the <tt>file-rc</tt> package, please refer
4463 to the documentation of that package.
4467 These scripts are referenced by symbolic links in the
4468 <tt>/etc/rc<var>n</var>.d</tt> directories. When changing
4469 runlevels, <prgn>init</prgn> looks in the directory
4470 <tt>/etc/rc<var>n</var>.d</tt> for the scripts it should
4471 execute, where <tt><var>n</var></tt> is the runlevel that
4472 is being changed to, or <tt>S</tt> for the boot-up
4477 The names of the links all have the form
4478 <tt>S<var>mm</var><var>script</var></tt> or
4479 <tt>K<var>mm</var><var>script</var></tt> where
4480 <var>mm</var> is a two-digit number and <var>script</var>
4481 is the name of the script (this should be the same as the
4482 name of the actual script in <tt>/etc/init.d</tt>).
4486 When <prgn>init</prgn> changes runlevel first the targets
4487 of the links whose names start with a <tt>K</tt> are
4488 executed, each with the single argument <tt>stop</tt>,
4489 followed by the scripts prefixed with an <tt>S</tt>, each
4490 with the single argument <tt>start</tt>. (The links are
4491 those in the <tt>/etc/rc<var>n</var>.d</tt> directory
4492 corresponding to the new runlevel.) The <tt>K</tt> links
4493 are responsible for killing services and the <tt>S</tt>
4494 link for starting services upon entering the runlevel.
4498 For example, if we are changing from runlevel 2 to
4499 runlevel 3, init will first execute all of the <tt>K</tt>
4500 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4501 all of the <tt>S</tt> prefixed scripts in that directory.
4502 The links starting with <tt>K</tt> will cause the
4503 referred-to file to be executed with an argument of
4504 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4509 The two-digit number <var>mm</var> is used to determine
4510 the order in which to run the scripts: low-numbered links
4511 have their scripts run first. For example, the
4512 <tt>K20</tt> scripts will be executed before the
4513 <tt>K30</tt> scripts. This is used when a certain service
4514 must be started before another. For example, the name
4515 server <prgn>bind</prgn> might need to be started before
4516 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4517 can set up its access lists. In this case, the script
4518 that starts <prgn>bind</prgn> would have a lower number
4519 than the script that starts <prgn>inn</prgn> so that it
4521 <example compact="compact">
4528 The two runlevels 0 (halt) and 6 (reboot) are slightly
4529 different. In these runlevels, the links with an
4530 <tt>S</tt> prefix are still called after those with a
4531 <tt>K</tt> prefix, but they too are called with the single
4532 argument <tt>stop</tt>.
4536 Also, if the script name ends <tt>.sh</tt>, the script
4537 will be sourced in runlevel <tt>S</tt> rather that being
4538 run in a forked subprocess, but will be explicitly run by
4539 <prgn>sh</prgn> in all other runlevels.
4544 <heading>Writing the scripts</heading>
4547 Packages that include daemons for system services should
4548 place scripts in <tt>/etc/init.d</tt> to start or stop
4549 services at boot time or during a change of runlevel.
4550 These scripts should be named
4551 <tt>/etc/init.d/<var>package</var></tt>, and they should
4552 accept one argument, saying what to do:
4555 <tag><tt>start</tt></tag>
4556 <item><p>start the service,</p></item>
4558 <tag><tt>stop</tt></tag>
4559 <item><p>stop the service,</p></item>
4561 <tag><tt>restart</tt></tag>
4562 <item><p>stop and restart the service,</p></item>
4564 <tag><tt>reload</tt></tag>
4565 <item><p>cause the configuration of the service to be
4566 reloaded without actually stopping and restarting
4567 the service,</p></item>
4569 <tag><tt>force-reload</tt></tag> <item><p>cause the
4570 configuration to be reloaded if the service supports
4571 this, otherwise restart the service.</p></item>
4574 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4575 <tt>force-reload</tt> options should be supported by all
4576 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4577 option is optional.</p>
4580 The <tt>init.d</tt> scripts should ensure that they will
4581 behave sensibly if invoked with <tt>start</tt> when the
4582 service is already running, or with <tt>stop</tt> when it
4583 isn't, and that they don't kill unfortunately-named user
4584 processes. The best way to achieve this is usually to use
4585 <prgn>start-stop-daemon</prgn>.</p>
4588 If a service reloads its configuration automatically (as
4589 in the case of <prgn>cron</prgn>, for example), the
4590 <tt>reload</tt> option of the <tt>init.d</tt> script
4591 should behave as if the configuration has been reloaded
4595 The <tt>/etc/init.d</tt> scripts should be treated as
4596 configuration files, either by marking them as
4597 <tt>conffile</tt>s or managing them correctly in the
4598 maintainer scripts (see <ref id="config files">). This is
4599 important since we want to give the local system
4600 administrator the chance to adapt the scripts to the local
4601 system, e.g., to disable a service without de-installing
4602 the package, or to specify some special command line
4603 options when starting a service, while making sure her
4604 changes aren't lost during the next package upgrade.
4608 These scripts should not fail obscurely when the
4609 configuration files remain but the package has been
4610 removed, as configuration files remain on the system after
4611 the package has been removed. Only when <prgn>dpkg</prgn>
4612 is executed with the <tt>--purge</tt> option will
4613 configuration files be removed. In particular, as the
4614 <tt>/etc/init.d/<var>package</var></tt> script itself is
4615 usually a <tt>conffile</tt>, it will remain on the system
4616 if the package is removed but not purged. Therefore, you
4617 should include a <tt>test</tt> statement at the top of the
4619 <example compact="compact">
4620 test -f <var>program-executed-later-in-script</var> || exit 0
4625 Often there are some variables in the <tt>init.d</tt>
4626 scripts whose values control the bahaviour of the scripts,
4627 and which a system administrator is likely to want to
4628 change. As the scripts themselves are frequently
4629 <tt>conffiles</tt>, modifying them requires that the
4630 administrator merge in their changes each time the package
4631 is upgraded and the <tt>conffile changes</tt>. To ease
4632 the burden on the system administrator, such configurable
4633 values should not be placed directly in the script.
4634 Instead, they should be placed in a file in
4635 <tt>/etc/default</tt>, which typically will have the same
4636 base name as the <tt>init.d</tt> script. This extra file
4637 should be sourced by the script when the script runs. It
4638 must contain only variable settings and comments in POSIX
4639 <prgn>sh</prgn> format. It should not be a
4640 <tt>conffile</tt>, but a configuration file maintained by
4641 the package maintainer scripts. See <ref id="config
4642 files"> for more details.
4646 To ensure that vital configurable values are always
4647 available, the <tt>init.d</tt> script should set default
4648 values for each of the shell variables it uses, either
4649 before sourcing the <tt>/etc/default/</tt> file or
4650 afterwards using something like the <tt>:
4651 ${VAR:=default}</tt> syntax. Also, the <tt>init.d</tt>
4652 script must behave sensibly and not fail if the
4653 <tt>/etc/default</tt> file is deleted.
4658 <heading>Managing the links</heading>
4661 The program <prgn>update-rc.d</prgn> is provided for
4662 package maintainers to arrange for the proper creation and
4663 removal of <tt>/etc/rc<var>n</var>.d</tt> symbolic links,
4664 or their functional equivalent if another method is being
4665 used. This may be used by maintainers in their packages'
4666 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4669 You must not include any <tt>/etc/rc<var>n</var>.d</tt>
4670 symbolic links in the actual archive or manually create or
4671 remove the symbolic links in maintainer scripts; you must
4672 use the <prgn>update-rc.d</prgn> program instead. (The
4673 former will fail if an alternative method of maintaining
4674 runlevel information is being used.) You must not include
4675 the <tt>/etc/rc<var>n</var>.d</tt> directories themselves
4676 in the archive either. (Only the <tt>sysvinit</tt>
4681 By default <prgn>update-rc.d</prgn> will start services in
4682 each of the multi-user state runlevels (2, 3, 4, and 5)
4683 and stop them in the halt runlevel (0), the single-user
4684 runlevel (1) and the reboot runlevel (6). The system
4685 administrator will have the opportunity to customize
4686 runlevels by simply adding, moving, or removing the
4687 symbolic links in <tt>/etc/rc<var>n</var>.d</tt> if
4688 symbolic links are being used, or by modifying
4689 <tt>/etc/runlevel.conf</tt> if the <tt>file-rc</tt> method
4694 To get the default behavior for your package, put in your
4695 <prgn>postinst</prgn> script
4696 <example compact="compact">
4697 update-rc.d <var>package</var> defaults >/dev/null
4699 and in your <prgn>postrm</prgn>
4700 <example compact="compact">
4701 if [ "$1" = purge ]; then
4702 update-rc.d <var>package</var> remove >/dev/null
4707 This will use a default sequence number of 20. If it does
4708 not matter when or in which order the <tt>init.d</tt>
4709 script is run, use this default. If it does, then you
4710 should talk to the maintainer of the <prgn>sysvinit</prgn>
4711 package or post to <tt>debian-devel</tt>, and they will
4712 help you choose a number.
4716 For more information about using <tt>update-rc.d</tt>,
4717 please consult its manpage <manref name="update-rc.d"
4724 <heading>Boot-time initialization</heading>
4727 There used to be another directory, <tt>/etc/rc.boot</tt>,
4728 which contained scripts which were run once per machine
4729 boot. This has been deprecated in favour of links from
4730 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4731 described in <ref id="/etc/init.d">. Packages must not
4732 place files in <tt>/etc/rc.boot</tt>.</p>
4735 <heading>Example</heading>
4738 The <prgn>bind</prgn> DNS (nameserver) package wants to
4739 make sure that the nameserver is running in multiuser
4740 runlevels, and is properly shut down with the system. It
4741 puts a script in <tt>/etc/init.d</tt>, naming the script
4742 appropriately <tt>bind</tt>. As you can see, the script
4743 interprets the argument <tt>reload</tt> to send the
4744 nameserver a <tt>HUP</tt> signal (causing it to reload its
4745 configuration); this way the system administrator can say
4746 <tt>/etc/init.d/bind reload</tt> to reload the name
4747 server. The script has one configurable value, which can
4748 be used to pass parameters to the named program at
4749 startup; this value is read from
4750 <tt>/etc/default/bind</tt> (see below).
4754 <example compact="compact">
4757 # Original version by Robert Leslie
4758 # <rob@mars.org>, edited by iwj and cs
4760 test -x /usr/sbin/named || exit 0
4762 # Source defaults file.
4764 if [ -f /etc/default/bind ]; then
4771 echo -n "Starting domain name service: named"
4772 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4777 echo -n "Stopping domain name service: named"
4778 start-stop-daemon --stop --quiet \
4779 --pidfile /var/run/named.pid --exec /usr/sbin/named
4783 echo -n "Restarting domain name service: named"
4784 start-stop-daemon --stop --quiet \
4785 --pidfile /var/run/named.pid --exec /usr/sbin/named
4786 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4790 force-reload|reload)
4791 echo -n "Reloading configuration of domain name service: named"
4792 start-stop-daemon --stop --signal 1 --quiet \
4793 --pidfile /var/run/named.pid --exec /usr/sbin/named
4797 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4807 Complementing the above init script is a configuration
4808 file <tt>/etc/default/bind</tt>, which contains
4809 configurable parameters used by the script. This would be
4810 created by the <prgn>postinst</prgn> script if it was not
4811 already present, and removed on purge by the
4812 <prgn>postrm</prgn> script.
4813 <example compact="compact">
4814 # Specified parameters to pass to named. See named(8).
4815 # You may uncomment the following line, and edit to taste.
4821 Another example on which you can base your
4822 <tt>/etc/init.d</tt> scripts is found in
4823 <tt>/etc/init.d/skeleton</tt>.
4827 If this package is happy with the default setup from
4828 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4829 and having named running in all runlevels, it can say in
4830 its <prgn>postinst</prgn>:
4831 <example compact="compact">
4832 update-rc.d bind defaults >/dev/null
4834 And in its <prgn>postrm</prgn>, to remove the links when the
4836 <example compact="compact">
4837 if [ "$1" = purge ]; then
4838 update-rc.d bind remove >/dev/null
4846 <heading>Console messages from <tt>init.d</tt> scripts</heading>
4849 This section describes the formats to be used for messages
4850 written to standard output by the <tt>/etc/init.d</tt>
4851 scripts. The intent is to improve the consistency of
4852 Debian's startup and shutdown look and feel. For this
4853 reason, please look very carefully at the details. We want
4854 the messages to have the same format in terms of wording,
4855 spaces, punctuation and case of letters.
4859 Here is a list of overall rules that you should use when you
4860 create output messages. They can be useful if you have a
4861 non-standard message that is not covered specifically in the
4869 Every message should fit in one line (fewer than 80
4870 characters), start with a capital letter and end with
4871 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
4877 If you want to express that the computer is working on
4878 something (that is, performing a specific task, not
4879 starting or stopping a program), we use an "ellipsis"
4880 (three dots: <tt>...</tt>). Note that we don't insert
4881 spaces before or after the dots. If the task has been
4882 completed we write <tt>done.</tt> and a line feed.
4888 Design your messages as if the computer is telling you
4889 what he is doing (let him be polite :-), but don't
4890 mention "him" directly. For example, if you think of
4892 <example compact="compact">
4893 I'm starting network daemons: nfsd mountd.
4896 <example compact="compact">
4897 Starting network daemons: nfsd mountd.
4905 There are standard message formats for the following
4906 situations. They should be used by the <tt>init.d</tt>
4913 <p>When daemons are started</p>
4916 If your script starts one or more daemons, the output
4917 should look like this (a single line, no leading
4919 <example compact="compact">
4920 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
4922 The <var>description</var> should describe the
4923 subsystem the daemon or set of daemons are part of,
4924 while <var>daemon-1</var> up to <var>daemon-n</var>
4925 denote each daemon's name (typically the file name of
4930 For example, the output of <tt>/etc/init.d/lpd</tt>
4932 <example compact="compact">
4933 Starting printer spooler: lpd.
4938 This can be achieved by saying
4939 <example compact="compact">
4940 echo -n "Starting printer spooler: lpd"
4941 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
4944 in the script. If you have more than one daemon to
4945 start, you should do the following:
4946 <example compact="compact">
4947 echo -n "Starting remote file system services:"
4948 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4949 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4950 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4953 This makes it possible for the user to see what takes
4954 so long and when the final daemon has been started.
4955 You should be careful where to put spaces: in the
4956 example above the system administrator can easily
4957 comment out a line if he don't wants to start a
4958 specific daemon, while the displayed message still
4964 <p>When a system parameter is being set</p>
4967 If you have to set up different system parameters
4968 during the system boot, you should use this format:
4969 <example compact="compact">
4970 Setting <var>parameter</var> to `<var>value</var>'.
4975 You can use a statement such as the following to get
4977 <example compact="compact">
4978 echo "Setting DNS domainname to \`$domainname'."
4983 Note that the left quotation mark (<tt>`</tt>) is
4984 different from the right one (<tt>'</tt>).
4989 <p>When a daemon is stopped or restarted</p>
4992 When you stop or restart a daemon, you should issue a
4993 message identical to the startup message, except that
4994 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
4995 or <tt>Restarting</tt> respectively.
4999 For example, stopping the printer daemon will like
5001 <example compact="compact">
5002 Stopping printer spooler: lpd.
5008 <p>When something is executed</p>
5011 There are several examples where you have to run a
5012 program at system startup or shutdown to perform a
5013 specific task, for example, setting the system's clock
5014 using <prgn>netdate</prgn> or killing all processes
5015 when the system shuts down. Your message should look
5017 <example compact="compact">
5018 Doing something very useful...done.
5020 You should print the <tt>done.</tt> immediately after
5021 the job has been completed, so that the user is
5022 informed why she has to wait. You can get this
5024 <example compact="compact">
5025 echo -n "Doing something very useful..."
5034 <p>When the configuration is reloaded</p>
5037 When a daemon is forced to reload its configuration
5038 files you should use the following format:
5039 <example compact="compact">
5040 Reloading <var>description</var> configuration...done.
5042 where <var>description</var> is the same as in the
5043 daemon starting message.
5051 <heading>Cron jobs</heading>
5054 Packages must not modify the configuration file
5055 <tt>/etc/crontab</tt>, and they must not modify the files in
5056 <tt>/var/spool/cron/crontabs</tt>.</p>
5059 If a package wants to install a job that has to be executed
5060 via cron, it should place a file with the name of the
5061 package in one or more of the following directories:
5062 <example compact="compact">
5067 As these directory names imply, the files within them are
5068 executed on a daily, weekly, or monthly basis,
5069 respectively. The exact times are listed in
5070 <tt>/etc/crontab</tt>.</p>
5073 All files installed in any of these directories must be
5074 scripts (e.g., shell scripts or Perl scripts) so that they
5075 can easily be modified by the local system administrator.
5076 In addition, they should be treated as configuration
5081 If a certain job has to be executed more frequently than
5082 daily, the package should install a file
5083 <tt>/etc/cron.d/<var>package</var></tt>. This file uses the
5084 same syntax as <tt>/etc/crontab</tt> and is processed by
5085 <prgn>cron</prgn> automatically. The file must also be
5086 treated as a configuration file. (Note that entries in the
5087 <tt>/etc/cron.d</tt> directory are not handled by
5088 <prgn>anacron</prgn>. Thus, you should only use this
5089 directory for jobs which may be skipped if the system is not
5093 The scripts or crontab entries in these directories should
5094 check if all necessary programs are installed before they
5095 try to execute them. Otherwise, problems will arise when a
5096 package was removed but not purged since configuration files
5097 are kept on the system in this situation.</p>
5101 <heading>Menus</heading>
5104 Menu entries should follow the current menu policy found in
5105 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5106 package. It may also be found on the Debian FTP site
5107 <ftpsite>ftp.debian.org</ftpsite> as the file
5108 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5109 or in the equivalent location on your local mirror.
5113 The Debian <tt>menu</tt> package provides a standard
5114 interface between packages providing applications and
5115 documents, and <em>menu programs</em> (either X window
5116 managers or text-based menu programs such as
5117 <prgn>pdmenu</prgn>).
5121 All packages that provide applications that need not be
5122 passed any special command line arguments for normal
5123 operation should register a menu entry for those
5124 applications, so that users of the <tt>menu</tt> package
5125 will automatically get menu entries in their window
5126 managers, as well in shells like <tt>pdmenu</tt>.</p>
5129 Please also refer to the <em>Debian Menu System</em>
5130 documentation that comes with the <tt>menu</tt> package for
5131 information about how to register your applications and web
5137 <heading>Multimedia handlers</heading>
5140 Packages which provide the ability to view/show/play,
5141 compose, edit or print MIME types should register themselves
5142 as such following the current MIME support policy found in
5143 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5144 package. It may also be found on the Debian FTP site
5145 <ftpsite>ftp.debian.org</ftpsite> as the file
5146 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5147 or in the equivalent location on your local mirror.
5151 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5152 is a mechanism for encoding files and data streams and
5153 providing meta-information about them, in particular their
5154 type (e.g. audio or video) and format (e.g. PNG, HTML,
5159 Registration of MIME type handlers allows programs like mail
5160 user agents and web browsers to to invoke these handlers to
5161 view, edit or display MIME types they don't support
5167 <heading>Keyboard configuration</heading>
5170 To achieve a consistent keyboard configuration so that all
5171 applications interpret a keyboard event the same way, all
5172 programs in the Debian distribution must be configured to
5173 comply with the following guidelines.
5177 The following keys must have the specified interpretations:
5180 <tag><tt><--</tt></tag>
5181 <item><p>delete the character to the left of the cursor</p></item>
5183 <tag><tt>Delete</tt></tag>
5184 <item><p>delete the character to the right of the cursor</p></item>
5186 <tag><tt>Control+H</tt></tag>
5187 <item><p>emacs: the help prefix</p></item>
5190 The interpretation of any keyboard events should be
5191 independent of the terminal that is used, be it a virtual
5192 console, an X terminal emulator, an rlogin/telnet session,
5197 The following list explains how the different programs
5198 should be set up to achieve this:
5203 <item><p><tt><--</tt> generates <tt>KB_Backspace</tt>
5206 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5211 X translations are set up to make
5212 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5213 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5214 is the vt220 escape code for the `delete character'
5215 key). This must be done by loading the X resources
5216 using <prgn>xrdb</prgn> on all local X displays, not
5217 using the application defaults, so that the
5218 translation resources used correspond to the
5219 <prgn>xmodmap</prgn> settings.</p></item>
5223 The Linux console is configured to make
5224 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5225 generate <tt>ESC [ 3 ~</tt>.</p></item>
5229 X applications are configured so that <tt><</tt>
5230 deletes left, and <tt>Delete</tt> deletes right. Motif
5231 applications already work like this.</p></item>
5233 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5237 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5238 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5239 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5243 Emacs is programmed to map <tt>KB_Backspace</tt> or
5244 the <tt>stty erase</tt> character to
5245 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5246 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5247 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5251 Other applications use the <tt>stty erase</tt>
5252 character and <tt>kdch1</tt> for the two delete keys,
5253 with ASCII DEL being `delete previous character' and
5254 <tt>kdch1</tt> being `delete character under
5261 This will solve the problem except for the following
5269 Some terminals have a <tt><--</tt> key that cannot
5270 be made to produce anything except <tt>^H</tt>. On
5271 these terminals Emacs help will be unavailable on
5272 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5273 character takes precedence in Emacs, and has been set
5274 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5275 available) can be used instead.</p></item>
5279 Some operating systems use <tt>^H</tt> for <tt>stty
5280 erase</tt>. However, modern telnet versions and all
5281 rlogin versions propagate <tt>stty</tt> settings, and
5282 almost all UNIX versions honour <tt>stty erase</tt>.
5283 Where the <tt>stty</tt> settings are not propagated
5284 correctly, things can be made to work by using
5285 <tt>stty</tt> manually.</p></item>
5289 Some systems (including previous Debian versions) use
5290 <prgn>xmodmap</prgn> to arrange for both
5291 <tt><--</tt> and <tt>Delete</tt> to generate
5292 <tt>KB_Delete</tt>. We can change the behavior of
5293 their X clients using the same X resources that we use
5294 to do it for our own clients, or configure our clients
5295 using their resources when things are the other way
5296 around. On displays configured like this
5297 <tt>Delete</tt> will not work, but <tt><--</tt>
5302 Some operating systems have different <tt>kdch1</tt>
5303 settings in their <tt>terminfo</tt> database for
5304 <tt>xterm</tt> and others. On these systems the
5305 <tt>Delete</tt> key will not work correctly when you
5306 log in from a system conforming to our policy, but
5307 <tt><--</tt> will.</p></item>
5313 <heading>Environment variables</heading>
5316 A program must not depend on environment variables to get
5317 reasonable defaults. (That's because these environment
5318 variables would have to be set in a system-wide
5319 configuration file like <tt>/etc/profile</tt>, which is not
5320 supported by all shells.)</p>
5323 If a program usually depends on environment variables for its
5324 configuration, the program should be changed to fall back to
5325 a reasonable default configuration if these environment
5326 variables are not present. If this cannot be done easily
5327 (e.g., if the source code of a non-free program is not
5328 available), the program must be replaced by a small
5329 `wrapper' shell script which sets the environment variables
5330 if they are not already defined, and calls the original program.</p>
5333 Here is an example of a wrapper script for this purpose:
5335 <example compact="compact">
5337 BAR=${BAR:-/var/lib/fubar}
5339 exec /usr/lib/foo/foo "$@"
5344 Furthermore, as <tt>/etc/profile</tt> is a configuration
5345 file of the <prgn>base-files</prgn> package, other packages must not
5346 put any environment variables or other commands into that
5352 <heading>Files</heading>
5356 <heading>Binaries</heading>
5359 Two different packages must not install programs with
5360 different functionality but with the same filenames. (The
5361 case of two programs having the same functionality but
5362 different implementations is handled via `alternatives.')
5363 If this case happens, one of the programs must be
5364 renamed. The maintainers should report this to the
5365 developers' mailing and try to find a consensus about
5366 which package will have to be renamed. If a consensus can
5367 not be reached, <em>both</em> programs must be
5371 Generally the following compilation parameters should be used:
5372 <example compact="compact">
5374 CFLAGS = -O2 -Wall # sane warning options vary between programs
5376 install -s # (or use strip on the files in debian/tmp)
5380 Note that by default all installed binaries should be stripped,
5381 either by using the <tt>-s</tt> flag to
5382 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5383 the binaries after they have been copied into
5384 <tt>debian/tmp</tt> but before the tree is made into a
5388 The <tt>-N</tt> flag should not be used. On a.out systems
5389 it may have been useful for some very small binaries, but
5390 for ELF it has no good effect.</p>
5393 Debugging symbols are useful for error diagnosis,
5394 investigation of core dumps (which may be submitted by users
5395 in bug reports), or testing and developing the
5396 software. Therefore it is recommended to support building
5397 the package with debugging information through the following
5398 interface: If the environment variable
5399 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5400 <tt>debug</tt>, compile the software with debugging
5401 information (usually this involves adding the <tt>-g</tt>
5402 flag to <tt>CFLAGS</tt>). This allows the generation of a
5403 build tree with debugging information. If the environment
5404 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5405 <tt>nostrip</tt>, do not strip the files at installation
5406 time. This allows one to generate a package with debugging
5407 information included. The following makefile snippet is only
5408 an example of how one may test for either condition:
5411 Rationale: Building by default with -g causes more
5412 wasted CPU cycles since the information is stripped away
5413 anyway. The package can by default build without -g if
5414 it also provides a mechanism to easily be rebuilt with
5415 debugging information. This can be done by providing a
5416 "build-debug" make target, or allowing the user to
5417 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5418 compiling that package.
5420 <p>Now this has several added benefits:
5421 <list compact="compact">
5424 It is actually easier to build debugging bins and
5425 libraries this way (no more editing debian/rules
5426 or similar) since it provides a documented way of
5427 getting this type of build.</p>
5431 There will be much less wasted CPU time for the
5432 autobuilders since not having debugging
5433 information (and hence also not having to strip
5434 it) will increase the speed of compiles. This
5435 skips an entire pass of the compiler.
5443 <example compact="compact">
5446 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5447 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5448 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5449 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5451 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5454 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5455 INSTALL_PROGRAM += -s
5459 Please note that the above example is merely informative,
5460 and is not a policy mandate. You may have to massage this
5461 example in order to make it work for your package.
5466 It is up to the package maintainer to decide what
5467 compilation options are best for the package. Certain
5468 binaries (such as computationally-intensive programs) will
5469 function better with certain flags (<tt>-O3</tt>, for
5470 example); feel free to use them. Please use good judgment
5471 here. Don't use flags for the sake of it; only use them
5472 if there is good reason to do so. Feel free to override
5473 the upstream author's ideas about which compilation
5474 options are best: they are often inappropriate for our
5475 environment.</p></sect>
5479 <heading>Libraries</heading>
5482 All libraries must have a shared version in the lib
5483 package and a static version in the lib-dev package. The
5484 shared version must be compiled with <tt>-fPIC</tt>, and
5485 the static version must not be. In other words, each
5486 <tt>*.c</tt> file will need to be compiled twice.</p>
5489 You must specify the gcc option <tt>-D_REENTRANT</tt>
5490 when building a library (either static or shared) to make
5491 the library compatible with LinuxThreads.</p>
5494 Note that all installed shared libraries should be
5496 <example compact="compact">
5497 strip --strip-unneeded <your-lib>
5499 (The option <tt>--strip-unneeded</tt> makes
5500 <prgn>strip</prgn> remove only the symbols which aren't
5501 needed for relocation processing.) Shared libraries can
5502 function perfectly well when stripped, since the symbols for
5503 dynamic linking are in a separate part of the ELF object
5507 Note that under some circumstances it may be useful to
5508 install a shared library unstripped, for example when
5509 building a separate package to support debugging.
5513 An ever increasing number of packages are using libtool to
5514 do their linking. The latest GNU libtools (>= 1.3a) can take
5515 advantage of the metadata in the installed libtool archive
5516 files (`*.la'). The main advantage of libtool's .la files is
5517 that it allows libtool to store and subsequently access
5518 metadata with respect to the libraries it builds. libtool
5519 will search for those files, which contain a lot of useful
5520 information about a library (e.g. dependency libraries for
5521 static linking). Also, they're <em>essential</em> for
5522 programs using libltdl.
5526 Certainly libtool is fully capable of linking against shared
5527 libraries which don't have .la files, but being a mere shell
5528 script it can add considerably to the build time of a
5529 libtool using package if that shell-script has to derive all
5530 this information from first principles for each library every
5531 time it is linked. With the advent of libtool-1.4 (and to a
5532 lesser extent libtool-1.3), the .la files will also store
5533 information about inter-library dependencies which cannot
5534 necessarily be derived after the .la file is deleted.
5538 Packages that use libtool to create shared libraries should
5539 include the <em>.la</em> files in the <em>-dev</em>
5540 packages, with the exception that if the package relies on
5541 libtool's <em>libltdl</em> library, in which case the .la
5542 files must go in the run-time library package. This is a
5543 good idea in general, and especially for static linking
5548 You must make sure that you use only released versions of
5549 shared libraries to build your packages; otherwise other
5550 users will not be able to run your binaries
5551 properly. Producing source packages that depend on
5552 unreleased compilers is also usually a bad
5559 <heading>Shared libraries</heading>
5562 Packages involving shared libraries should be split up
5563 into several binary packages.</p>
5566 For a straightforward library which has a development
5567 environment and a runtime kit including just shared
5568 libraries you need to create two packages:
5569 <tt><var>libraryname</var><var>soname</var></tt>
5570 (<var>soname</var> is the shared object name of the shared
5571 library: it's the thing that has to match exactly between
5572 building an executable and running it for the dynamic
5573 linker to be able run the program; usually the
5574 <var>soname</var> is the major number of the library) and
5575 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5578 If you prefer only to support one development version at a
5579 time you may name the development package
5580 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5581 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5582 ensure that the user only installs one development version
5583 at a time (after all, different development versions are
5584 likely to have the same header files in them, causing a
5585 filename clash if both are installed). Typically the
5586 development version should also have an exact version
5587 dependency on the runtime library, to make sure that
5588 compilation and linking happens correctly.</p>
5591 Packages which use the shared library should have a
5592 dependency on the name of the shared library package,
5593 <tt><var>libraryname</var><var>soname</var></tt>. When
5594 the <var>soname</var> changes you can have both versions
5595 of the library installed while moving from the old library
5599 If your package has some run-time support programs which
5600 use the shared library you must not put them in
5601 the shared library package. If you do that then you won't
5602 be able to install several versions of the shared library
5603 without getting filename clashes. Instead, either create
5604 a third package for the runtime binaries (this package
5605 might typically be named
5606 <tt><var>libraryname</var>-runtime</tt>; note the absence
5607 of the <var>soname</var> in the package name) or if the
5608 development package is small include them in there.</p>
5611 If you have several shared libraries built from the same
5612 source tree you may lump them all together into a single
5613 shared library package, provided that you change all their
5614 <var>soname</var>s at once (so that you don't get filename
5615 clashes if you try to install different versions of the
5616 combined shared libraries package).</p>
5619 You should follow the directions in the <em>Debian Packaging
5620 Manual</em> (or other documentation of the Debian
5621 packaging tools) for putting the shared library in its
5622 package, and you must include a <tt>shlibs</tt> control area
5623 file with details of the dependencies for packages which use
5627 Shared libraries should not be installed
5628 executable, since <prgn>ld.so</prgn> does not require this
5629 and trying to execute a shared library results in a core
5634 <heading>Scripts</heading>
5637 All command scripts, including the package maintainer
5638 scripts inside the package and used by <prgn>dpkg</prgn>,
5639 should have a <tt>#!</tt> line naming the shell to be used
5640 to interpret them.</p>
5643 In the case of Perl scripts this should be
5644 <tt>#!/usr/bin/perl</tt>.</p>
5647 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5648 should almost certainly start with <tt>set -e</tt> so that
5649 errors are detected. Every script should use
5650 <tt>set -e</tt> or check the exit status of <em>every</em>
5654 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5655 symbolic link to any POSIX compatible shell, if <tt>echo
5656 -n</tt> does not generate a newline.
5659 Debian policy specifies POSIX behavior for /bin/sh, but
5660 echo -n has widespread use in the Linux community
5661 (including especially debian policy, the linux kernel
5662 source, many debian scripts, etc.). This echo -n
5663 mechanism is valid but not required under POSIX, hence
5664 this explicit addition. Also, rumour has it that this
5665 shall be mandated under the LSB anyway.
5669 specifying `<tt>/bin/sh</tt>' as interpreter should only
5670 use POSIX features. If a script requires non-POSIX
5671 features from the shell interpreter, the appropriate shell
5672 must be specified in the first line of the script (e.g.,
5673 `<tt>#!/bin/bash</tt>') and the package must depend on the
5674 package providing the shell (unless the shell package is
5675 marked `Essential', e.g., in the case of
5680 You may wish to restrict your script to POSIX features when possible so
5681 that it may use <tt>/bin/sh</tt> as its interpreter. If
5682 your script works with <prgn>ash</prgn>, it's probably
5683 POSIX compliant, but if you are in doubt, use
5684 <tt>/bin/bash</tt>.</p>
5687 Perl scripts should check for errors when making any
5688 system calls, including <tt>open</tt>, <tt>print</tt>,
5689 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5692 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5693 as scripting languages. See <em>Csh Programming
5694 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5695 FAQs. It can be found on
5696 <url id="http://language.perl.com/versus/csh.whynot">, or
5697 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5698 or even on <ftpsite>ftp.cpan.org</ftpsite>
5699 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5700 If an upstream package comes with <prgn>csh</prgn> scripts
5701 then you must make sure that they start with
5702 <tt>#!/bin/csh</tt> and make your package depend on the
5703 <prgn>c-shell</prgn> virtual package.</p>
5706 Any scripts which create files in world-writeable
5707 directories (e.g., in <tt>/tmp</tt>) must use a
5708 mechanism which will fail if a file with the same name
5712 The Debian base distribution provides the
5713 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5714 for use by scripts for this purpose.</p></sect>
5718 <heading>Symbolic links</heading>
5721 In general, symbolic links within a top-level directory
5722 should be relative, and symbolic links pointing from one
5723 top-level directory into another should be absolute. (A
5724 top-level directory is a sub-directory of the root
5728 In addition, symbolic links should be specified as short
5729 as possible, i.e., link targets like `foo/../bar' are
5733 Note that when creating a relative link using
5734 <prgn>ln</prgn> it is not necessary for the target of the
5735 link to exist relative to the working directory you're
5736 running <prgn>ln</prgn> from; nor is it necessary to
5737 change directory to the directory where the link is to be
5738 made. Simply include the string that should appear as the
5739 target of the link (this will be a pathname relative to
5740 the directory in which the link resides) as the first
5741 argument to <prgn>ln</prgn>.</p>
5744 For example, in your <prgn>Makefile</prgn> or
5745 <tt>debian/rules</tt>, do things like:
5746 <example compact="compact">
5747 ln -fs gcc $(prefix)/bin/cc
5748 ln -fs gcc debian/tmp/usr/bin/cc
5749 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5750 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5754 A symbolic link pointing to a compressed file should
5755 always have the same file extension as the referenced
5756 file. (For example, if a file `<tt>foo.gz</tt>' is
5757 referenced by a symbolic link, the filename of the link
5758 has to end with `<tt>.gz</tt>' too, as in
5759 `bar.gz.')</p></sect>
5763 <heading>Device files</heading>
5766 Packages must not include device files in the package file
5770 If a package needs any special device files that are not
5771 included in the base system, it must call
5772 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
5773 after asking the user for permission to do so.</p>
5776 Packages must not remove any device files in the
5777 <prgn>postrm</prgn> or any other script. This is left to the
5778 system administrator.</p>
5781 Debian uses the serial devices
5782 <tt>/dev/ttyS*</tt>. Programs using the old
5783 <tt>/dev/cu*</tt> devices should be changed to use
5784 <tt>/dev/ttyS*</tt>.</p>
5787 <sect id="config files">
5788 <heading>Configuration files</heading>
5790 <heading>Definitions</heading>
5793 <tag>configuration file</tag>
5795 A file that affects the operation of program, or
5796 provides site- or host-specific information, or
5797 otherwise customizes the behavior of program.
5798 Typically, configuration files are intended to be
5799 modified by the system administrator (if needed or
5800 desired) to conform to local policy or provide more
5801 useful site-specific behavior.</p>
5804 <tag><tt>conffile</tt></tag>
5806 A file listed in a package's <tt>conffiles</tt>
5807 file, and is treated specially by <prgn>dpkg</prgn>
5808 (see the <em>Debian Packaging Manual</em>).</p>
5814 The distinction between these two is important; they are
5815 not interchangeable concepts. Almost all
5816 <tt>conffiles</tt> are configuration files, but many
5817 configuration files are not <tt>conffiles</tt>.</p>
5820 Note that a script that embeds configuration information
5821 (such as most of the files in <tt>/etc/init.d</tt> and
5822 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5823 configuration file and should be treated as such.</p>
5827 <heading>Location</heading>
5829 Any configuration files created or used by your package
5830 must reside in <tt>/etc</tt>. If there are several you
5831 should consider creating a subdirectory of <tt>/etc</tt>
5832 named after your package.</p>
5835 If your package creates or uses configuration files
5836 outside of <tt>/etc</tt>, and it is not feasible to modify
5837 the package to use the <tt>/etc</tt>, you should still put
5838 the files in <tt>/etc</tt> and create symbolic links to
5839 those files from the location that the package
5844 <heading>Behavior</heading>
5846 Configuration file handling must conform to the following
5848 <list compact="compact">
5850 <p>local changes must be preserved during a package
5854 <p>configuration files must be preserved when the
5855 package is removed, and only deleted when the
5856 package is purged.</p>
5861 The easy way to achieve this behavior is to make the
5862 configuration file a <tt>conffile</tt>. This is
5863 appropriate only if it is possible to distribute a default
5864 version that will work for most installations, although
5865 some system administrators may choose to modify it. This
5866 implies that the default version will be part of the
5867 package distribution, and must not be modified by the
5868 maintainer scripts during installation (or at any other
5873 In order to ensure that local changes are preserved
5874 correctly, no package may contain or make hard links to
5878 Rationale: There are two problems with hard links.
5879 The first is that some editors break the link while
5880 editing one of the files, so that the two files may
5881 unwittingly become different. The second is that
5882 <prgn>dpkg</prgn> might break the hard link while
5883 upgrading <tt>conffile</tt>s.
5889 The other way to do it is via the maintainer scripts.
5890 In this case, the configuration file must not be listed as
5891 a <tt>conffile</tt> and must not be part of the package
5892 distribution. If the existence of a file is required for
5893 the package to be sensibly configured it is the
5894 responsibility of the package maintainer to write scripts
5895 which correctly create, update, maintain and
5896 remove-on-purge the file. These scripts must be idempotent
5897 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5898 re-run them due to errors during installation or removal),
5899 must cope with all the variety of ways <prgn>dpkg</prgn>
5900 can call maintainer scripts, must not overwrite or
5901 otherwise mangle the user's configuration without asking,
5902 must not ask unnecessary questions (particularly during
5903 upgrades), and otherwise be good citizens.</p>
5906 The scripts are not required to configure every possible option for
5907 the package, but only those necessary to get the package
5908 running on a given system. Ideally the sysadmin should not
5909 have to do any configuration other than that done
5910 (semi-)automatically by the <prgn>postinst</prgn> script.</p>
5913 A common practice is to create a script called
5914 <tt><var>package</var>-configure</tt> and have the
5915 package's <prgn>postinst</prgn> call it if and only if the
5916 configuration file does not already exist. In certain
5917 cases it is useful for there to be an example or template
5918 file which the maintainer scripts use. Such files should
5919 be in <tt>/usr/share/<package></tt> or
5920 <tt>/usr/lib/<package></tt> with a symbolic link
5921 from <tt>/usr/share/doc/<package>/examples</tt>
5922 if they are examples, and should be
5923 perfectly ordinary <prgn>dpkg</prgn>-handled files
5924 (<em>not</em> <tt>conffiles</tt>).
5928 These two styles of configuration file handling must
5929 not be mixed, for that way lies madness:
5930 <prgn>dpkg</prgn> will ask about overwriting the file
5931 every time the package is upgraded.</p>
5936 <heading>Sharing configuration files</heading>
5938 Packages which specify the same file as
5939 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5944 The maintainer scripts must not alter the conffile of
5945 <em>any</em> package, including the one the scripts belong
5949 If two or more packages use the same configuration file
5950 and it is reasonable for both to be installed at the same
5951 time, one of these packages must be defined as
5952 <em>owner</em> of the configuration file, i.e., it will be
5953 the package to list that distributes the file and lists it
5954 as a <tt>conffile</tt>. Other packages that use the
5955 configuration file must depend on the owning package if
5956 they require the configuration file to operate. If the
5957 other package will use the configuration file if present,
5958 but is capable of operating without it, no dependency need
5962 If it is desirable for two or more related packages to
5963 share a configuration file <em>and</em> for all of the
5964 related packages to be able to modify that configuration
5965 file, then the following should be done:
5969 have one of the related packages (the "core"
5970 package) manage the configuration file with
5971 maintainer scripts as described in the previous
5975 the core package should also provide a program that
5976 the other packages may use to modify the
5977 configuration file.</p>
5981 the related packages must use the provided program
5982 to make any modifications to the configuration file.
5983 They should either depend on the core package to
5984 guarantee that the configuration modifier program is
5985 available or accept gracefully that they cannot
5986 modify the configuration file if it is not.</p>
5991 Sometimes it's appropriate to create a new package which
5992 provides the basic infrastructure for the other packages
5993 and which manages the shared configuration files. (Check
5994 out the <tt>sgml-base</tt> package as an example.)</p>
5998 <heading>User configuration files ("dotfiles")</heading>
6001 Files in <tt>/etc/skel</tt> will automatically be copied
6002 into new user accounts by <prgn>adduser</prgn>. They
6003 should not be referenced there by any program.</p>
6006 Therefore, if a program needs a dotfile to exist in
6007 advance in <tt>$HOME</tt> to work sensibly, that dotfile
6008 should be installed in <tt>/etc/skel</tt> (and listed in
6009 conffiles, if it is not generated and modified dynamically
6010 by the package's installation scripts).</p>
6013 However, programs that require dotfiles in order to
6014 operate sensibly (dotfiles that they do not create
6015 themselves automatically, that is) are a bad thing, and
6016 programs should be configured by the Debian default
6017 installation as close to normal as possible.</p>
6020 Therefore, if a program in a Debian package needs to be
6021 configured in some way in order to operate sensibly that
6022 configuration should be done in a site-wide global
6023 configuration file elsewhere in <tt>/etc</tt>. Only if the
6024 program doesn't support a site-wide default configuration
6025 and the package maintainer doesn't have time to add it
6026 may a default per-user file be placed in
6027 <tt>/etc/skel</tt>.</p>
6030 <tt>/etc/skel</tt> should be as empty as we can make it.
6031 This is particularly true because there is no easy
6032 mechanism for ensuring that the appropriate dotfiles are
6033 copied into the accounts of existing users when a package
6039 <heading>Log files</heading>
6041 The traditional approach to log files has been to set up ad
6042 hoc log rotation schemes using simple shell scripts and
6043 cron. While this approach is highly customizable, it
6044 requires quite a lot of sysadmin work. Even though the
6045 original Debian system helped a little by automatically
6046 installing a system which can be used as a template, this
6047 was deemed not enough.
6051 A better scheme is to use logrotate, a GPL'd program
6052 developed by Red Hat, which centralizes log management. It
6053 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
6054 and a directory where packages can drop logrotation info
6055 (<tt>/etc/logrotate.d</tt>).
6059 Log files should usually be named
6060 <tt>/var/log/<var>package</var>.log</tt>. If you have many
6061 log files, or need a separate directory for permissions
6062 reasons (<tt>/var/log</tt> is writable only by
6063 <tt>root</tt>), you should usually create a directory named
6064 <tt>/var/log/<var>package</var></tt>.</p>
6067 Log files must be rotated occasionally so
6068 that they don't grow indefinitely; the best way to do this
6069 is to drop a script into the directory
6070 <tt>/etc/logrotate.d</tt> and use the facilities provided by
6071 logrotate. Here is a good example for a logrotate config
6072 file (for more information see <manref name="logrotate"
6074 <example compact="compact">
6080 /etc/init.d/foo force-reload
6084 Which rotates all files under `/var/log/foo', saves 12
6085 compressed generations, and sends a HUP signal at the end of
6091 Log files should be removed when the package is
6092 purged (but not when it is only removed), by checking the
6093 argument to the <prgn>postrm</prgn> script (see the <em>Debian
6094 Packaging Manual</em> for details).</p>
6099 <heading>Permissions and owners</heading>
6102 The rules in this section are guidelines for general use.
6103 If necessary you may deviate from the details below.
6104 However, if you do so you must make sure that what is done
6105 is secure and you should try to be as consistent as possible
6106 with the rest of the system. You should probably also
6107 discuss it on <prgn>debian-devel</prgn> first.</p>
6110 Files should be owned by <tt>root.root</tt>, and made
6111 writable only by the owner and universally readable (and
6112 executable, if appropriate).</p>
6115 Directories should be mode 755 or (for group-writability)
6116 mode 2775. The ownership of the directory should be
6117 consistent with its mode: if a directory is mode 2775, it
6118 should be owned by the group that needs write access to
6122 Setuid and setgid executables should be mode 4755 or 2755
6123 respectively, and owned by the appropriate user or group.
6124 They should not be made unreadable (modes like 4711 or
6125 2711 or even 4111); doing so achieves no extra security,
6126 because anyone can find the binary in the freely available
6127 Debian package, it is merely inconvenient. For the same
6128 reason you should not restrict read or execute permissions
6129 on non-set-id executables.</p>
6132 Some setuid programs need to be restricted to particular
6133 sets of users, using file permissions. In this case they
6134 should be owned by the uid to which they are set-id, and
6135 by the group which should be allowed to execute them.
6136 They should have mode 4754; there is no point in making
6137 them unreadable to those users who must not be allowed to
6141 You must not arrange that the system administrator can only
6142 reconfigure the package to correspond to their local
6143 security policy by changing the permissions on a binary.
6144 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
6145 to conffiles and other similar objects) have their
6146 permissions reset to the distributed permissions when the
6147 package is reinstalled. Instead you should consider (for
6148 example) creating a group for people allowed to use the
6149 program(s) and making any setuid executables executable
6150 only by that group.</p>
6153 If you need to create a new user or group for your package
6154 there are two possibilities. Firstly, you may need to
6155 make some files in the binary package be owned by this
6156 user or group, or you may need to compile the user or
6157 group id (rather than just the name) into the binary
6158 (though this latter should be avoided if possible, as in
6159 this case you need a statically allocated id).</p>
6162 If you need a statically allocated id, you must ask for a
6163 user or group id from the base system
6164 maintainer, and must not release the package until you
6165 have been allocated one. Once you have been allocated one
6166 you must make the package depend on a version of the base
6167 system with the id present in <tt>/etc/passwd</tt> or
6168 <tt>/etc/group</tt>, or alternatively arrange for your
6169 package to create the user or group itself with the
6170 correct id (using <tt>adduser</tt>) in its pre- or
6171 post-installation script (the latter is to be preferred if
6172 it is possible).</p>
6175 On the other hand, the program might be able to determine the
6176 uid or gid from the group name at runtime, so that a
6177 dynamic id can be used. In this case you should choose an
6178 appropriate user or group name, discussing this on
6179 <prgn>debian-devel</prgn> and checking with the base
6180 system maintainer that it is unique and that they do not
6181 wish you to use a statically allocated id instead. When
6182 this has been checked you must arrange for your package to
6183 create the user or group if necessary using
6184 <prgn>adduser</prgn> in the pre- or post-installation
6185 script (again, the latter is to be preferred if it is
6189 Note that changing the numeric value of an id associated with a name
6190 is very difficult, and involves searching the file system for all
6191 appropriate files. You need to think carefully whether a static or
6192 dynamic id is required, since changing your mind later will cause
6197 <chapt id="customized-programs">
6198 <heading>Customized programs</heading>
6200 <sect id="arch-spec">
6201 <heading>Architecture specification strings</heading>
6204 If a program needs to specify an <em>architecture specification
6205 string</em> in some place, the following format should be used:
6206 <example compact="compact">
6207 <arch>-<os>
6209 where `<arch>' is one of the following: i386, alpha, arm, m68k,
6210 powerpc, sparc and `<os>' is one of: linux, gnu. Use
6211 of <em>gnu</em> in this string is reserved for the GNU/Hurd
6212 operating system.</p>
6214 Note, that we don't want to use `<arch>-debian-linux'
6215 to apply to the rule `architecture-vendor-os' since this
6216 would make our programs incompatible to other Linux
6217 distributions. Also note, that we don't use
6218 `<arch>-unknown-linux', since the `unknown' does not
6219 look very good.</p></sect>
6223 <heading>Daemons</heading>
6226 The configuration files <tt>/etc/services</tt>,
6227 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6228 by the <prgn>netbase</prgn> package and may not be modified
6229 by other packages.</p>
6232 If a package requires a new entry in one of these files, the
6233 maintainer should get in contact with the
6234 <prgn>netbase</prgn> maintainer, who will add the entries
6235 and release a new version of the <prgn>netbase</prgn>
6239 The configuration file <tt>/etc/inetd.conf</tt> must not be
6240 modified by the package's scripts except via the
6241 <prgn>update-inetd</prgn> script or the
6242 <prgn>DebianNet.pm</prgn> Perl module.</p>
6245 If a package wants to install an example entry into
6246 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6247 exactly one hash character (<tt>#</tt>). Such lines are
6248 treated as `commented out by user' by the
6249 <prgn>update-inetd</prgn> script and are not changed or
6250 activated during a package updates.</p></sect>
6254 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
6257 Some programs need to create pseudo-ttys. This should be done
6258 using Unix98 ptys if the C library supports it. The resulting
6259 program must not be installed setuid root, unless that
6260 is required for other functionality.
6264 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6265 <tt>/var/log/lastlog</tt> must be installed writeable by
6266 group utmp. Programs who need to modify those files must
6267 be installed setgid utmp.
6272 <heading>Editors and pagers</heading>
6275 Some programs have the ability to launch an editor or pager
6276 program to edit or display a text document. Since there are
6277 lots of different editors and pagers available in the Debian
6278 distribution, the system administrator and each user should
6279 have the possibility to choose his/her preferred editor and
6283 In addition, every program should choose a good default
6284 editor/pager if none is selected by the user or system
6288 Thus, every program that launches an editor or pager must
6289 use the EDITOR or PAGER environment variables to determine
6290 the editor/pager the user wants to get started. If these
6291 variables are not set, the programs <tt>/usr/bin/editor</tt>
6292 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
6295 These two files are managed through `alternatives.' That is,
6296 every package providing an editor or pager must call the
6297 <prgn>update-alternatives</prgn> script to register these
6301 If it is very hard to adapt a program to make us of the
6302 EDITOR and PAGER variables, that program may be configured
6303 to use <tt>/usr/bin/sensible-editor</tt> and
6304 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
6305 respectively. These are two scripts provided in the Debian
6306 base system that check the EDITOR and PAGER variables and
6307 launch the appropriate program or fall back to
6308 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
6312 A program may also use the VISUAL environment variable to
6313 determine the user's choice of editor. If it exists, it
6314 should take precedence over EDITOR. This is in fact what
6315 <tt>/usr/bin/sensible-editor</tt> does.</p>
6318 It is not required for a package to depend on
6319 `editor' and `pager', nor is it required for a package to
6320 provide such virtual packages.
6323 The Debian base system already provides an editor and
6332 <sect id="web-appl">
6333 <heading>Web servers and applications</heading>
6336 This section describes the locations and URLs that should
6337 be used by all web servers and web application in the Debian
6343 <p>Cgi-bin executable files are installed in the
6345 <example compact="compact">
6346 /usr/lib/cgi-bin/<cgi-bin-name>
6348 and should be referred to as
6349 <example compact="compact">
6350 http://localhost/cgi-bin/<cgi-bin-name>
6355 <item><p>Access to html documents</p>
6358 Html documents for a package are stored in
6359 <tt>/usr/share/doc/<var>package</var></tt> but should
6360 be accessed via symlinks as
6361 <tt>/usr/doc/<var>package</var></tt><footnote> for
6362 backward compatibility, see <ref id="usrdoc"></footnote>
6363 and can be referred to as
6364 <example compact="compact">
6365 http://localhost/doc/<package>/<filename>
6370 <item><p>Web Document Root</p>
6373 Web Applications should try to avoid storing files in
6374 the Web Document Root. Instead they should use the
6375 /usr/share/doc/<package> directory for documents and
6376 register the Web Application via the menu package. If
6377 access to the web-root is unavoidable then use
6378 <example compact="compact">
6381 as the Document Root. This might be just a
6382 symbolic link to the location where the sysadmin has
6383 put the real document root.</p>
6386 </enumlist></p></sect>
6389 <sect id="mail-transport-agents">
6390 <heading>Mail transport, delivery and user agents</heading>
6393 Debian packages which process electronic mail, whether
6394 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6395 must make sure that they are compatible with the
6396 configuration decisions below. Failure to do this may
6397 result in lost mail, broken <tt>From:</tt> lines, and other
6398 serious brain damage!</p>
6401 The mail spool is <tt>/var/mail</tt> and the interface
6402 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6403 per the FHS). On older systems, the mail spool may be
6404 physically located in /var/spool/mail, but all access to the
6405 mail spool should be via the /var/mail symlink. The mail
6406 spool is part of the base system and not part of the MTA
6411 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6412 programs (like IMAP daemons) must lock the mailbox in an
6413 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6414 be combined with dot locking. To avoid deadlocks, a
6415 program should use <tt>fcntl()</tt> first and dot locking
6416 after this or alternatively implement the two locking
6417 methods in a non blocking way<footnote>
6419 If it is not possible to establish both locks, the
6420 system shouldn't wait for the second lock to be
6421 established, but remove the first lock, wait a (random)
6422 time, and start over locking again.</p>
6423 </footnote>. Using the functions <tt>maillock</tt> and
6424 <tt>mailunlock</tt> provided by the
6425 <tt>liblockfile*</tt><footnote>
6427 <tt>liblockfile</tt> version >>1.01</p>
6428 </footnote> packages is the recommended way to realize this.
6432 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6433 unless the user has chosen otherwise. A MUA may remove a
6434 mailbox (unless it has nonstandard permissions) in which
6435 case the MTA or another MUA must recreate it if needed.
6436 Mailboxes must be writable by group mail.</p>
6439 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6440 be setgid mail to do the locking mentioned above (and
6441 must obviously avoid accessing other users' mailboxes
6442 using this privilege).</p>
6445 <tt>/etc/aliases</tt> is the source file for the system mail
6446 aliases (e.g., postmaster, usenet, etc.), it is the one
6447 which the sysadmin and <prgn>postinst</prgn> scripts may edit.
6448 After <tt>/etc/aliases</tt> is edited the program or human
6449 editing it must call <prgn>newaliases</prgn>. All MTA
6450 packages must come with a <prgn>newaliases</prgn> program,
6451 even if it does nothing, but older MTA packages do not do
6452 this so programs should not fail if <prgn>newaliases</prgn>
6453 cannot be found.</p>
6456 The convention of writing <tt>forward to
6457 <var>address</var></tt> in the mailbox itself is not
6458 supported. Use a <tt>.forward</tt> file instead.</p>
6461 The <prgn>rmail</prgn> program used by UUCP
6462 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6463 Likewise, <prgn>rsmtp</prgn>, for receiving
6464 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6468 If you need to know what name to use (for example) on
6469 outgoing news and mail messages which are generated locally,
6470 you should use the file <tt>/etc/mailname</tt>. It will
6471 contain the portion after the username and <tt>@</tt> (at)
6472 sign for email addresses of users on the machine (followed
6476 A package should check for the existence of this file. If
6477 it exists it should use it without comment. (An MTA's
6478 prompting configuration script may wish to prompt the user
6479 even if it finds this file exists.) If it does not exist it
6480 should prompt the user for the value and store it in
6481 <tt>/etc/mailname</tt> as well as using it in the package's
6482 configuration. The prompt should make it clear that the
6483 name will not just be used by that package. For example, in
6484 this situation the INN package says:
6485 <example compact="compact">
6486 Please enter the `mail name' of your system. This is the
6487 hostname portion of the address to be shown on outgoing
6488 news and mail messages. The default is
6489 <var>syshostname</var>, your system's host name. Mail
6490 name [`<var>syshostname</var>']:
6492 where <var>syshostname</var> is the output of <tt>hostname
6498 <heading>News system configuration</heading>
6501 All the configuration files related to the NNTP (news)
6502 servers and clients should be located under
6503 <tt>/etc/news</tt>.</p>
6506 There are some configuration issues that apply to a number
6507 of news clients and server packages on the machine. These
6511 <tag>/etc/news/organization</tag>
6512 <item><p>A string which should appear as the
6513 organization header for all messages posted
6514 by NNTP clients on the machine</p></item>
6516 <tag>/etc/news/server</tag>
6517 <item><p>Contains the FQDN of the upstream NNTP
6518 server, or localhost if the local machine is
6519 an NNTP server.</p></item>
6522 Other global files may be added as required for cross-package news
6523 configuration.</p></sect>
6527 <heading>Programs for the X Window System</heading>
6530 <em>Programs that may be configured with support for the X Window
6531 System</em> must be configured to do so and must declare any
6532 package dependencies necessary to satisfy their runtime
6533 requirements when using the X Window System, unless the package
6534 in question is of standard or higher priority, in which case
6535 X-specific binaries may be split into a separate package, or
6536 alternative versions of the package with X support may be
6542 <em>Packages which provide an X server</em> that, directly or
6543 indirectly, communicates with real input and display hardware
6544 should declare in their control data that they provide the
6545 virtual package <tt>xserver</tt>.
6548 This implements current practice, and provides an actual
6549 policy for usage of the "xserver" virtual package which
6550 appears in the virtual packages list. In a nutshell, X
6551 servers that interface directly with the display and input
6552 hardware or via another subsystem (e.g., GGI) should provide
6553 xserver. Things like Xvfb, Xnest, and Xprt should not.
6559 <em>Packages that provide a terminal emulator</em> for the X
6560 Window System which support a terminal type with a terminfo
6561 description provided in the <tt>ncurses-base</tt> package
6562 should declare in their control data that they provide the
6563 virtual package <tt>x-terminal-emulator</tt>. They should
6564 also register themselves as an alternative for
6565 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6570 <em>Packages that provide window managers</em> should declare in
6571 their control data that they provide the virtual package
6572 <tt>x-window-manager</tt>. They should also register themselves as an
6573 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6574 calculated as follows:
6575 <list compact="compact">
6576 <item>Start with a priority of 20.</item>
6577 <item>If the window manager supports the Debian menu system,
6578 add 20 points if this support is available in the
6579 package's default configuration (i.e., no
6580 configuration files belonging to the system or user
6581 have to be edited to activate the feature); if
6582 configuration files must be modified, add only 10
6584 <item>If the window manager permits the X session to be
6585 restarted using a <em>different</em> window manager
6586 (without killing the X server) in its default
6587 configuration, add 10 points; otherwise add
6593 <em>Packages that provide fonts for the X Window System</em>
6594 must do a number of things to ensure that they are both
6595 available without modification of the X or font server
6596 configuration, and that they do not corrupt files used by
6597 other font packages to register information about themselves.
6600 Fonts of any type supported by the X Window System
6601 should be be in a separate binary package from any
6602 executables, libraries, or documentation (except that
6603 specific to the fonts shipped); if a program or
6604 library is <em>unusable</em> without one or more
6605 specific fonts, the package containing the program or
6606 library should declare a dependency on the package(s)
6607 containing the font(s) it requires.
6610 BDF fonts should be converted to PCF fonts with the
6611 <tt>bdftopcf</tt> utility (available in the
6612 <tt>xutils</tt> package), <tt>gzip</tt>ped, and
6613 placed in a directory that corresponds to their
6615 <list compact="compact">
6617 100 dpi fonts should be placed in
6618 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6621 75 dpi fonts should be placed in
6622 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6625 Character-cell fonts, cursor fonts, and other
6626 low-resolution fonts should be placed in
6627 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6632 Speedo fonts should be placed in
6633 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6636 Type 1 fonts should be placed in
6637 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6638 metric files are available, they may be placed here as
6642 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6643 other than those listed above should be neither created nor
6644 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6645 excepted for historical reasons, but installation of files into
6646 these directories remains discouraged.)
6649 Font packages may, instead of placing files directly in
6650 the X font directories listed above, provide symbolic links in
6651 the font directory which point to the files' actual location
6652 in the filesystem. Such a location should comply with the
6656 Font packages should not contain both 75dpi and 100dpi
6657 versions of a font. If both are available, they should be
6658 provided in separate binary packages with "-75dpi" or "-100dpi"
6659 appended to the names of the packages containing the
6660 corresponding fonts.
6663 Fonts destined for the <tt>misc</tt> subdirectory should
6664 not be included in the same package as 75dpi or 100dpi fonts;
6665 instead, they should be provided in a separate package with
6666 "-misc" appended to its name.
6669 Font packages <em>must not</em> provide the files
6670 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6671 <tt>fonts.scale</tt> in a font directory.
6672 <list compact="compact">
6674 <tt>fonts.dir</tt> files must not be provided at
6678 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6679 files, if needed, should be provided in the
6681 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6682 where <em>fontdir</em> is the name of the
6684 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6685 package's corresponding fonts are stored (e.g.,
6686 <tt>75dpi</tt> or <tt>misc</tt>),
6687 <em>package</em> is the name of the package that
6688 provides these fonts, and <em>extension</em> is
6689 either <tt>scale</tt> or <tt>alias</tt>,
6690 whichever corresponds to the file
6696 Font packages must declare a dependency on
6697 <tt>xutils</tt> and, in the package
6698 post-installation and post-removal scripts, invoke the
6699 <tt>mkfontdir</tt> command on each directory into
6700 which they installed fonts.
6703 Font packages that provide one or more
6704 <tt>fonts.scale</tt> files as described above must declare a
6705 versioned dependency on <tt>xutils (>=
6706 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6707 directory into which they installed fonts
6708 <em>before</em> invoking <tt>mkfontdir</tt> on that
6709 directory. This invocation must occur in both the
6710 post-installation and post-removal scripts.
6713 Font packages that provide one or more
6714 <tt>fonts.alias</tt> files as described above must
6715 declare a versioned dependency on <tt>xutils
6716 (>= 4.0.2)</tt> and, in the package
6717 post-installation and post-removal scripts, invoke
6718 <tt>update-fonts-alias</tt> on each directory into
6719 which they installed fonts.
6722 Font packages must not provide alias names for the
6723 fonts they include which collide with alias names already in
6724 use by fonts already packaged.
6727 Font packages must not provide fonts with the same XLFD
6728 registry name as another font already packaged.
6734 <em>Application defaults</em> files must be installed in the
6735 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6736 localized subdirectory of <tt>/etc/X11/</tt> as described in
6737 the <em>X Toolkit Intrinsics - C Language Interface</em>
6738 manual is also permitted). They must be registered as
6739 <em>conffile</em>s or handled as configuration files. For
6740 programs that are not linked against the X Toolkit (Xt)
6741 library, customization of programs' X resources may also be
6742 supported with the provision of a file with the same name as
6743 that of the package placed in the
6744 <tt>/etc/X11/Xresources/</tt> directory, which must
6745 registered as a <em>conffile</em> or handled as a
6746 configuration file. <em>Important:</em> packages that
6747 install files into the <tt>/etc/X11/Xresources/</tt>
6748 directory <em>must</em> declare a conflict with <tt>xbase
6749 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6750 possible for the installing package to destroy a
6751 previously-existing <tt>/etc/X11/Xresources</tt> file which
6752 had been customized by the system administrator.
6756 <em>Packages using the X Window System should abide by the
6757 FHS standard whenever possible</em>; they should install
6758 binaries, libraries, manual pages, and other files in
6759 FHS-mandated locations wherever possible. This means that
6760 files must not be installed into <tt>/usr/X11R6/bin/</tt>,
6761 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt>
6762 unless this is necessary for the package to operate
6763 properly. Configuration files for window managers and
6764 display managers should be placed in a subdirectory of
6765 <tt>/etc/X11/</tt> corresponding to the package name due
6766 to these programs' tight integration with the mechanisms
6767 of the X Window System. Application-level programs should
6768 use the <tt>/etc/</tt> directory unless otherwise mandated
6769 by policy. The installation of files into subdirectories
6770 of <tt>/usr/X11R6/include/X11/</tt> and
6771 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6772 package maintainers should determine if subdirectories of
6773 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6774 instead (symlinks from the X11R6 directories to
6775 FHS-compliant locations is encouraged if the program is
6776 not easily configured to look elsewhere for its files).
6777 Packages must not provide or install files into the
6778 directories <tt>/usr/bin/X11/</tt>,
6779 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6780 Files within a package should, however, make reference to
6781 these directories, rather than their X11R6-named
6782 counterparts <tt>/usr/X11R6/bin/</tt>,
6783 <tt>/usr/X11R6/include/X11/</tt>, and
6784 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6785 referred to have not been moved to FHS-compliant
6790 <em>Programs that require the non-DFSG-compliant OSF/Motif
6791 library</em> should be compiled against and tested with
6792 LessTif (a free re-implementation of Motif) instead. If the
6793 maintainer judges that the program or programs do not work
6794 sufficiently well with LessTif to be distributed and
6795 supported, but do so when compiled against Motif, then two
6796 versions of the package should be created; one linked
6797 statically against Motif and with <tt>-smotif</tt> appended
6798 to the package name, and one linked dynamically against
6799 Motif and with <tt>-dmotif</tt> appended to the package
6800 name. Both Motif-linked versions are dependent upon
6801 non-DFSG-compliant software and thus cannot be uploaded to
6802 the main distribution; if the software is itself
6803 DFSG-compliant it may be uploaded to the contrib
6804 distribution. While known existing versions of OSF/Motif
6805 permit unlimited redistribution of binaries linked against
6806 the library (whether statically or dynamically), it is the
6807 package maintainer's responsibility to determine whether
6808 this is permitted by the license of the copy of OSF/Motif in
6809 his or her possession.
6814 <heading>Perl programs and modules</heading>
6816 Perl programs and modules should follow the current Perl
6817 policy as defined in the file found on
6818 <ftpsite>ftp.debian.org</ftpsite> in
6819 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
6820 or your local mirror. In addition, it is included in the
6821 <tt>debian-policy</tt> package.
6826 <heading>Emacs lisp programs</heading>
6829 Please refer to the `Debian Emacs Policy' (documented in
6830 <tt>debian-emacs-policy.gz</tt> of the
6831 <prgn>emacsen-common</prgn> package) for details of how to
6832 package emacs lisp programs.</p></sect>
6836 <heading>Games</heading>
6839 The permissions on /var/games are 755
6840 <tt>root.root</tt>.</p>
6843 Each game decides on its own security policy.</p>
6846 Games which require protected, privileged access to
6847 high-score files, savegames, etc., may be made
6848 set-<em>group</em>-id (mode 2755) and owned by
6849 <tt>root.games</tt>, and use files and directories with
6850 appropriate permissions (770 <tt>root.games</tt>, for
6851 example). They must not be made
6852 set-<em>user</em>-id, as this causes security problems. (If
6853 an attacker can subvert any set-user-id game they can
6854 overwrite the executable of any other, causing other players
6855 of these games to run a Trojan horse program. With a
6856 set-group-id game the attacker only gets access to less
6857 important game data, and if they can get at the other
6858 players' accounts at all it will take considerably more
6862 Some packages, for example some fortune cookie programs, are
6863 configured by the upstream authors to install with their
6864 data files or other static information made unreadable so
6865 that they can only be accessed through set-id programs
6866 provided. You should not do this in a Debian package: anyone can
6867 download the <tt>.deb</tt> file and read the data from it,
6868 so there is no point making the files unreadable. Not
6869 making the files unreadable also means that you don't have
6870 to make so many programs set-id, which reduces the risk of a
6874 As described in the FHS, binaries of games should be
6875 installed in the directory <tt>/usr/games</tt>. This also
6876 applies to games that use the X Window System. Manual pages
6877 for games (X and non-X games) should be installed in
6878 <tt>/usr/share/man/man6</tt>.</p>
6882 <chapt id="docs"><heading>Documentation</heading>
6886 <heading>Manual pages</heading>
6889 You should install manual pages in <prgn>nroff</prgn> source
6890 form, in appropriate places under <tt>/usr/share/man</tt>. You
6891 should only use sections 1 to 9 (see the FHS for more
6892 details). You must not install a preformatted `cat
6896 Each program, utility, and function should have an
6897 associated manpage included in the same package. It is
6898 suggested that all configuration files also have a manual
6899 page included as well.
6903 If no manual page is available for a particular program,
6904 utility, function or configuration file and this is reported as a bug on
6905 debian-bugs, a symbolic link from the requested manual page
6906 to the <manref name="undocumented" section="7"> manual page
6907 may be provided. This symbolic link can be created from
6908 <tt>debian/rules</tt> like this:
6909 <example compact="compact">
6910 ln -s ../man7/undocumented.7.gz \
6911 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6913 This manpage claims that the lack of a manpage has been
6914 reported as a bug, so you may only do this if it really has
6915 (you can report it yourself, if you like). Do not close the
6916 bug report until a proper manpage is available.</p>
6919 You may forward a complaint about a missing manpage to the
6920 upstream authors, and mark the bug as forwarded in the
6921 Debian bug tracking system. Even though the GNU Project do
6922 not in general consider the lack of a manpage to be a bug,
6923 we do; if they tell you that they don't consider it a bug
6924 you should leave the bug in our bug tracking system open
6928 Manual pages should be installed compressed using <tt>gzip
6932 If one manpage needs to be accessible via several names it
6933 is better to use a symbolic link than the <tt>.so</tt>
6934 feature, but there is no need to fiddle with the relevant
6935 parts of the upstream source to change from <tt>.so</tt> to
6936 symlinks: don't do it unless it's easy. You should not create hard
6937 links in the manual page directories, nor put
6938 absolute filenames in <tt>.so</tt> directives. The filename
6939 in a <tt>.so</tt> in a manpage should be relative to the
6940 base of the manpage tree (usually
6941 <tt>/usr/share/man</tt>).</p></sect>
6945 <heading>Info documents</heading>
6948 Info documents should be installed in <tt>/usr/share/info</tt>.
6949 They should be compressed with <tt>gzip -9</tt>.</p>
6952 Your package should call <prgn>install-info</prgn> to update the Info
6954 file, in its post-installation script:
6955 <example compact="compact">
6956 install-info --quiet --section Development Development \
6957 /usr/share/info/foobar.info
6961 It is a good idea to specify a section for the location of
6962 your program; this is done with the <tt>--section</tt>
6963 switch. To determine which section to use, you should look
6964 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6965 relevant (or create a new section if none of the current
6966 sections are relevant). Note that the <tt>--section</tt>
6967 flag takes two arguments; the first is a regular expression
6968 to match (case-insensitively) against an existing section,
6969 the second is used when creating a new one.</p>
6972 You should remove the entries in the pre-removal script:
6973 <example compact="compact">
6974 install-info --quiet --remove /usr/share/info/foobar.info
6978 If <prgn>install-info</prgn> cannot find a description entry
6979 in the Info file you must supply one. See <manref
6980 name="install-info" section="8"> for details.</p>
6984 <heading>Additional documentation</heading>
6987 Any additional documentation that comes with the package may
6988 be installed at the discretion of the package maintainer.
6989 Text documentation should be installed in a directory
6990 <tt>/usr/share/doc/<var>package</var></tt>, where
6991 <var>package</var> is the name of the package, and
6992 compressed with <tt>gzip -9</tt> unless it is small.</p>
6995 If a package comes with large amounts of documentation which
6996 many users of the package will not require you should create
6997 a separate binary package to contain it, so that it does not
6998 take up disk space on the machines of users who do not need
6999 or want it installed.</p>
7002 It is often a good idea to put text information files
7003 (<tt>README</tt>s, changelogs, and so forth) that come with
7004 the source package in <tt>/usr/share/doc/<var>package</var></tt>
7005 in the binary package. However, you don't need to install
7006 the instructions for building and installing the package, of
7010 Files in <tt>/usr/share/doc</tt> should not be referenced by
7011 any program, and the system administrator should be able to
7012 delete them without causing any programs to break. Any files
7013 that are referenced by programs but are also useful as
7014 standalone documentation should be installed under
7015 <tt>/usr/share/<package>/</tt> and symlinked in
7016 <tt>/usr/share/doc/<package>/</tt>.
7022 <heading>Accessing the documentation</heading>
7025 Former Debian releases placed all additional documentation
7026 in <tt>/usr/doc/<var>package</var></tt>. To realize a
7028 <tt>/usr/share/doc/<var>package</var></tt>, each package
7029 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
7030 that points to the new location of its documentation in
7031 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
7032 symlinks will be removed in the future, but they have to be
7033 there for compatibility reasons until all packages have
7034 moved and the policy is changed accordingly.</footnote>.
7035 The symlink must be created when the package is installed;
7036 it cannot be contained in the package itself due to problems
7037 with <prgn>dpkg</prgn>. One reasonable way to accomplish
7038 this is to put the following in the package's
7039 <prgn>postinst</prgn>:
7040 <example compact="compact">
7041 if [ "$1" = "configure" ]; then
7042 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
7043 -a -d /usr/share/doc/#PACKAGE# ]; then
7044 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
7048 And the following in the package's <prgn>prerm</prgn>:
7049 <example compact="compact">
7050 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
7051 -a -L /usr/doc/#PACKAGE# ]; then
7052 rm -f /usr/doc/#PACKAGE#
7059 <heading>Preferred documentation formats</heading>
7062 The unification of Debian documentation is being carried out
7066 If your package comes with extensive documentation in a
7067 mark up format that can be converted to various other formats
7068 you should if possible ship HTML versions in a binary
7069 package, in the directory
7070 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
7073 <p>The rationale: The important thing here is that HTML
7074 docs should be available in <em>some</em> package, not
7075 necessarily in the main binary package, though. </p>
7080 Other formats such as PostScript may be provided at your
7084 <sect id="copyrightfile">
7085 <heading>Copyright information</heading>
7088 Every package must be accompanied by a verbatim copy of its
7089 copyright and distribution license in the file
7090 /usr/share/doc/<package>/copyright. This file must
7091 neither be compressed nor be a symbolic link.</p>
7094 In addition, the copyright file must say where the upstream
7095 sources (if any) were obtained, and should explain briefly what
7096 modifications were made in the Debian version of the package
7097 compared to the upstream one. It should name the original
7098 authors of the package and the Debian maintainer(s) who were
7099 involved with its creation.</p>
7102 A copy of the file which will be installed in
7103 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
7104 in <tt>debian/copyright</tt>.</p>
7108 /usr/share/doc/<package> may be a symbolic link to a
7109 directory in /usr/share/doc only if two packages both come from
7110 the same source and the first package has a "Depends"
7111 relationship on the second. These rules are important
7112 because copyrights must be extractable by mechanical
7116 Packages distributed under the UCB BSD license, the Artistic
7117 license, the GNU GPL, and the GNU LGPL should refer to the
7118 files /usr/share/common-licenses/BSD,
7119 /usr/share/common-licenses/Artistic,
7120 /usr/share/common-licenses/GPL, and
7121 /usr/share/common-licenses/LGPL.
7124 Why "licenses" and not "copyright"? Because
7125 <tt>/usr/doc/copyright</tt> used to contain all the
7126 copyright files, plus the four common licenses GPL,
7127 LGPL, Artistic and BSD. Now individual copyright files
7128 for packages are no longer in a common directory. Once
7129 <tt>/usr/doc/copyright</tt> is almost empty it makes
7130 sense to rename "copyright" to "licenses"
7133 Why "common-licenses" and not "licenses"? Because if I
7134 put just "licenses" I'm sure I will receive a bug report
7135 saying "license foo is not included in the licenses
7136 directory. They are not all the licenses, just a few
7137 common ones. I could use /usr/share/doc/common-licenses
7138 but I think this is too long, and, after all, the GPL
7139 does not "document" anything, it is merely a license.
7145 You should not use the copyright file as a general <tt>README</tt>
7146 file. If your package has such a file it should be
7147 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
7148 <tt>README.Debian</tt> or some other appropriate place.</p>
7152 <heading>Examples</heading>
7155 Any examples (configurations, source files, whatever),
7156 should be installed in a directory
7157 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7158 files should not be referenced by any program: they're there
7159 for the benefit of the system administrator and users, as
7160 documentation only. Architecture-specific example files
7161 should be installed in a directory
7162 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
7163 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
7164 to files in it. Or the latter directory may be a symlink to
7168 <sect id="instchangelog">
7169 <heading>Changelog files</heading>
7172 Packages that are not Debian-native must contain a copy of
7173 <tt>debian/changelog</tt> file from the Debian source tree
7174 in <tt>/usr/share/doc/<var>package</var></tt> as
7175 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7176 available, it should be accessible as
7177 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7178 plain text. If the upstream changelog is distributed in
7179 HTML, it should be made available in that form as
7180 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7181 and the <tt>changelog.gz</tt> should be generated using, eg,
7182 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
7183 do not already conform to this naming convention, then this
7184 may be achieved either by renaming the files, or adding a
7185 symbolic link, at the maintainer's discretion.
7188 Rationale: People should not have to look into two
7189 places for upstream changelogs merely because they are
7197 All these files should be installed compressed using <tt>gzip -9</tt>,
7198 as they will become large with time even if they start out
7203 If the package has only one changelog which is used both as
7204 the Debian changelog and the upstream one because there is
7205 no separate upstream maintainer then that changelog should
7206 usually be installed as
7207 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7208 there is a separate upstream maintainer, but no upstream
7209 changelog, then the Debian changelog should still be called
7210 <tt>changelog.Debian.gz</tt>.</p>