\input texinfo @c -*-texinfo-*- @setfilename guidelines.info @set DATE 26th January 1996 @setchapternewpage off @iftex @center @titlefont{Debian Linux Packaging Guidelines} @tex \vskip2pt \hrule height 2pt width \hsize \vskip2pt @end tex @sp 0.5 @center @value{DATE} @end iftex @ifinfo @format START-INFO-DIR-ENTRY * Guidelines: (guidelines). How to make Debian packages. END-INFO-DIR-ENTRY @end format @end ifinfo @node Top, Additional Information, (dir), (dir) @ifinfo @top Debian Linux Packaging Guidelines @end ifinfo This file documents the steps that must be taken in the preparation of a Debian Linux package. All submissions to be included in the distribution proper and all packages to be considered for @file{contrib} or @file{non-free} availability @emph{must} conform to the guidelines and standards described in this document or they cannot be included or made available at the archive with the distribution. Please read the Guidelines carefully. If you have comments or questions, please contact @code{debian-devel@@pixar.com}. If you are planning on going further than just contributing a package (i.e., if you plan to maintain it for an extended period of time or if you are generally interested in becoming more involved in the Project), you should join the @code{debian-devel} mailing list. For more details, read @file{info/mailing-lists.txt}, available at any Debian Linux archive. (This file was last updated on @value{DATE}. Please check the most recent @file{dpkg} package at any Debian Linux archive for a potentially more up to date copy.) @menu * Additional Information:: Where other info is to be found. * Package Copyright:: A few words about the importance of understanding the package copyright. * Package Content:: Requirements for the package content. * Source Package:: Creating the source package. * Binary Package:: Creating the binary package. * Control Files:: The binary package control files. * Appendix:: More specific details about some aspects. @end menu @node Additional Information, Package Copyright, Top, Top @unnumbered Additional Information These Guidelines are intended to be fairly general. More specific information is available about certain aspects of building packages, such as how to use the features of Init under Debian Linux and how to interact with some more technical details of dpkg's operation. This information can be found in the directory @file{doc/package-developer} at any Debian Linux archive. At the time of this writing, the following documents are available: @table @file @item virtual-package-names-list.text The list of virtual package names currently in use, together with the procedure for getting new virtual package names allocated. @item auto-deconfiguration.txt How dpkg can sometimes automatically deconfigure packages in order to do bulk installations smoothly. @item dpkg-essential-flag.txt How to tell dpkg a package is essential and should not be removed. (This is for the use of base system packages only.) @item dpkg-disappear-replace.txt What happens when a package appears to have been completely replaced. @end table In the future, we hope also to make available: @table @file @item copyright.txt How to choose a good copyright notice to attach to new programs. @item version-ordering.txt The algorithm with which packages' version numbers are compared. @end table Also, you should download the sample files and the sample package (GNU Hello) available in @file{standards/samples}. You may use any of this material as a starting point for new packages. The following sample files, incidentally, are available: @itemize @bullet @item debian.README @item debian.control @item debian.postinst @item debian.postrm @item debian.rules @end itemize Some more detailed information about certain topics is available in the appendix to this document (@pxref{Appendix}). @node Package Copyright, Package Content, Additional Information, Top @unnumbered Package Copyright Please study the copyright of your submission @emph{carefully} and @emph{understand it} before proceeding! If you have doubts or questions, please ask! In order to understand how we classify and distribute certain packages, it is important to understand the distinction between being freely available and being freely redistributable. Being @dfn{freely available}, quite simply, means that the software can be made available freely, at least for non-commercial purposes and in its original, unmodified form. This includes packages made available freely that have restrictions on non-commercial use, redistribution of modifications, etc. Being freely available, therefore, has nothing to do with being able to modify and redistribute the software. It only means that you can get a copy of the software without having to pay (and it does not necessarily mean that you can @emph{use} the software without having to pay---shareware is an example of freely available software). @dfn{freely redistributable}, while generally being freely available, goes beyond just being freely available. Freely redistributable means that that the software, in addition to being able to be made available freely, must be able to be freely modified and redistributed without restriction. All submissions to be included in the distribution proper @emph{must} be freely redistributable. In addition to the distribution, the Project maintains two separate archives of software packages with the distribution: the @file{contrib} archive and the @file{non-free} archive. @file{contrib} is an archive of user-contributed packages that are not maintained by the Project, packages that were once maintained by the Project but that are no longer actively maintained, and packages that are maintained by the Project but that are not yet considered ready for inclusion in the distribution proper (i.e., ALPHA and BETA packages). As above, all submissions for inclusion in the @file{contrib} archive @emph{must} be freely redistributable. @file{non-free} is an archive of packages with either restrictive or unclear terms of copying or modification. If a package has @emph{any} restrictions on modification or redistribution, it can not be included in the distribution or @file{contrib} archive. It can only be included in the @file{non-free} archive, and then only if it is freely available. In summary, in order to be included in the distribution proper or the @file{contrib} archive, a package must be @emph{freely redistributable}. Anyone must be able to make copies of it, modify it, redistribute it with their modifications in place, include it on a CD-ROM, or generally sell it. To be included in the @file{non-free} archive, a package may have restrictions, as long as the package remains @emph{freely available}. We must be available to make it available freely at the archive, and anyone must be able to make copies of it and use it for at least non-commercial, personal purposes. Software that will typically be included in @file{non-free} are software that does not allow commercial distribution, software that does not allow modification or redistribution of modifications, commercial ``demos'', and ``shareware''. When in doubt, send mail to @file{debian-devel@@lists.debian.org}. Be prepared to provide us with the copyright statement. Software covered by the GPL, public domain software and BSD-like copyrights are safe; be wary of the phrases ``commercial use prohibited'' and ``distribution restricted''. Every package submission @emph{must} be accompanied by verbatim copy of its copyright (with the exceptions of public domain packages and those covered by the UCB BSD licence or the GNU GPL or LGPL; in these cases simply indicate which is appropriate). This information must be included in a file installed to the directory @file{/usr/doc/copyright}. See below for details. @node Package Content, Source Package, Package Copyright, Top @unnumbered Package Content The following requirements apply equally to both the binary and source packages. In either case, when files have been installed, they must conform to the requirements described in this section. The primary rule in Debian Linux is to follow the Linux @dfn{File System Standard} (@dfn{FSSTND}). The location of installed files @emph{must} comply @emph{fully} with the FSSTND. The latest version of this document can be found alongside the Guidelines or at @file{tsx-11.mit.edu} in @file{/pub/linux/docs/linux-standards/fsstnd}. Specific questions about following the standard should be addressed to Daniel Quinlan, the FSSTND coordinator, at @code{quinlan@@yggdrasil.com}. In addition to the FSSTND, all Debian Linux packages must follow the guidelines below. @itemize @bullet @item Directories should be mode 755 or (for group-writability) mode 2775, with the exception of special ``system'' directories that need to be another mode. The ownership of the directory should be consistent with its mode---if a directory is mode 2775, it should be owned by the group that needs write access to it, of course. Use common sense in assigning permissions and ownerships to directories, and make sure that what is done is secure if it is ``non-standard''. @item Normal binaries should be mode 755 and owned by @code{root.root}. If there is a good reason to use a different mode or ownership, you may do so, but you must try to be as consistent as possible with the rest of the system. If you need to use a different mode or ownership, please discuss it with @code{imurdock@@debian.org}. @item Setuid binaries should normally be mode 4755 (not 4711!) and, of course, owned by the appropriate user. @item Setgid binaries should normally be mode 2755 (not 2711!) and, of course, owned by the appropriate group. @item Library files should generally be mode 644 and owned by @code{root.root}; shared libraries should be mode 755. If the package requires different permissions or ownerships to function correctly, they should be used instead. @item Manual pages should be mode 644 and owned by @code{root.root}. The @file{nroff} source must be installed. You should @emph{not} install a preformatted ``cat page'', and you should only use sections 1 to 9---see the FSSTND for more details. If no manual page is available for a particular program, utility or function and this is reported as a bug on debian-bugs, a symbolic link from the requested manual page to the @file{undocumented}(7) manual page should be provided. This symbolic link can be created from @file{debian.rules} like this: @smallexample ln -s ../man7/undocumented.7 debian-tmp/usr/man/man[1-9]/the_requested_manpage.[1-9] @end smallexample Do not close the bug report until a proper manpage is available. You may forward the complaint to the upstream maintainers, and mark the bug as forwarded in the Debian bug tracking system. The GNU Project do not in general consider the lack of a manpage to be a bug, but we do - if they tell you to go away leave the bug open anyway. @item Info documents should be mode 644, owned by @code{root.root}, and compressed with @file{gzip -9} when installed. The package must call @file{install-info} to update the Info @file{dir} file. This should be done in the post-installation script (@file{postinst}), like this: @smallexample install-info --quiet /usr/info/foobar.info @end smallexample The entries should be removed by the pre-removal script (@file{prerm}), like this: @smallexample install-info --quiet --remove /usr/info/foobar.info @end smallexample It is also a good idea to specify a section for the Info @file{dir} entry. This is done with the @file{--section} switch. To determine which section to use, you should use look at @file{/usr/info/dir} on your system and choose the most relevant (or create a new section if none of the current sections are relevant). If @file{install-info} cannot find a description entry in the Info file you will have to supply one. See @file{install-info}(8) for details. @item If a package contains any shared libraries you will have to invoke @file{ldconfig} in both the @file{postinst} and @file{prerm} scripts to correctly update the library links. See @file{ldconfig}(8) for details. @item Any additional documentation that comes with the package can be installed at the discretion of the package maintainer. Text documentation should be mode 644, owned by @code{root.root}, installed to @file{/usr/doc}, and compressed with @file{gzip -9} unless it is small. If a subdirectory of @file{/usr/doc} is warranted, please do create one. Please do not install DVI, PostScript, or large textual documentation in the same package; upload such documentation as a separate package (installing its files in @file{/usr/doc}) so that it can be made available with the distribution. If a user has the need for the documentation, they can easily get it from the archive, CD-ROM, etc., but it should not take up disk space on the machines of the user who do not need or want it installed. @item Create a file named @file{/usr/doc/copyright/<@i{package}>} which gives details of the authorship and copyright of the package. If the package is distributed under the GNU General Public Licence, the GNU Library General Public Licence or the Regents of the University of California at Berkeley (BSD) licence, please say so instead of including a copy of the licence. The files @file{BSD}, @file{GPL}, and @file{LGPL} will be available in the @file{/usr/doc/copyright} directory for you to refer to. @file{/usr/doc/copyright/<@i{package}>} should not be compressed. @emph{All} authorship and copyright information from the original source package must be included in the @file{/usr/doc/copyright/<@i{package}>} file. @item Any example files (for example, sample configuration files) should be placed in the directory @file{/usr/doc/examples}. If the file is normally a hidden file, such as @file{.emacs}, then please call it @file{dot.emacs}, to avoid confusion. Again, you may create a subdirectory if it is needed. @item All symbolic links should be relative, not absolute. Absolute links, in general, cause problems when a file system is not mounted where it ``normally'' resides (for example, when mounted via NFS). In certain cases, however, relative links may also cause similar problems. I have generally made links into @file{/etc} and @file{/var} absolute and all other links relative. There may be other cases in which absolute links are necessary. Therefore, in the @file{Makefile} or @file{debian.rules}, do not do: @smallexample install: all [...] ln -fs /usr/bin/gcc /usr/bin/cc [...] @end smallexample Instead, do: @smallexample ln -fs gcc /usr/bin/cc @end smallexample or @smallexample ( cd /usr/bin ; ln -fs gcc cc ) @end smallexample Please do not create hard links in the manual page directories. In these cases, you should use relative symbolic links or files that @file{.so} (roff for `source') others instead. @item All command scripts should have a @code{#!} line naming the shell to be used to interpret them. @item In the case of Perl scripts this should be @code{#!/usr/bin/perl} or sometimes @code{#!/bin/perl}, as follows: if the script is a critical one that may be called when the @file{/usr} partition is unmounted or broken it should use @file{/bin/perl}. Otherwise (especially if the script is not specifically targetted at Debian) it should use Perl's standard location, @file{/usr/bin/perl}. @item Generally the following compilation parameters should be used: @display CC = gcc CFLAGS = -O2 -g -Wall # sane warning options vary between programs LDFLAGS = # none (or -N, if appropriate; see below) install -s (or strip) @end display Note that all installed binaries should be stripped, either by using the @code{-s} flag to @file{install}, or by calling @file{strip} on the binaries after they have been copied into the @file{debian-tmp} but before the tree is made into a package. Make sure that you do not link with @code{-g}, as this makes a.out compilers produce huge statically linked binaries. The @code{-g} flag is useful on compilation so that you have available a full set of debugging symbols in your built source tree, in case anyone should file a bug report involving (for example) a core dump. @code{-N} should only be used on binaries that are very small (less than 8K with the @code{-N} option, roughly) and are not likely to have multiple instances in memory. Do not use @code{-N} on daemons, no matter how small they are. It is up to the package maintainer to decide what compilation options are best for the package. Certain binaries (such as computationally-intensive programs) may function better with certain flags (@code{-O3}, for example); feel free to use them. Please use good judgment here. Don't add flags for the sake of adding flags; only add flags if there is good reason to do so. @item Please make sure that you use only released versions of shared libraries to build your packages; otherwise other users will not be able to run your binaries properly. Producing source packages that depend on unreleased compilers is also usually a bad idea. @item Logfiles should usually be named @file{/var/log/}, or @file{/var/log/.} if you have several logfiles. It may be appropriate to create a directory. Make sure that any logfiles are rotated occasionally so that they don't grow indefinitely; the best way to do this is to use @file{savelog} from the cron package in an @file{/etc/cron.daily}, @file{/etc/cron.weekly} or @file{/etc/cron.monthly} script. @item Please check with the base system maintainer (Ian Murdock) before using users or groups other than @code{root} and others specified in this document. @end itemize @node Source Package, Binary Package, Package Content, Top @unnumbered Source Package The source package should contain a file called @file{debian.rules} which contains at least the following targets, to be invoked in the top level directory: @smallexample build binary clean @end smallexample @file{debian.rules} should start with @smallexample #!/usr/bin/make -f @end smallexample @noindent and be executable. It is a good idea to arrange for it not to fail obscurely when invoked in the wrong directory, for example by testing for the existence of a file in the source directory. @itemize @bullet @item The @file{build} target should perform all non-interactive configuration and compilation of the package. If a package has an interactive pre-build configuration routine, the source package should be built @emph{after} this has taken place. For some packages, notably ones where the same source tree is compiled in different ways to produce two binary packages, the @file{build} target does not make much sense. For these packages it is good enough to provide two (or more) targets (@file{build-a} and @file{build-b} or whatever) for each of the ways of building the package, and a @file{build} target that does nothing. The @file{binary} target will have to build the package in each of the possible ways and make the binary package out of each. @item The @file{binary} target of @file{debian.rules} should be all that is necessary for the user to build the binary package. The binary package should be created using @file{dpkg} and placed in the parent of the top level directory. The next section describes how to construct binary packages from the @file{binary} target. @item The @file{clean} target should undo the effects of the @file{build} target and the @file{binary} target, except that it should leave alone any @file{../<@i{package}>-<@i{version}>.deb} file created by a run of @file{binary}. @item Additional targets may exist in @file{debian.rules}. We recommend using @file{source} and @file{diff} targets to build the Debianised source package and the Debianisation context diff, respectively. These files should be placed in @file{../foo-<@i{version}>.tar.gz} and @file{../foo-<@i{version}>.diff.gz}. The @file{install} target, for installing into a running system direct from the Debianised source tree, is no longer required. The sample @file{debian.rules} provides @file{source} and @file{diff} targets that should work with little or no alteration, providing that the package-specific variables at the top of the script have been properly defined. @item If you need to edit a @file{Makefile} where @file{configure} scripts are used, you should edit the @file{.in} files rather than editing the @file{Makefile} directly. This allows the user to reconfigure the package if necessary. You should @emph{not} configure the package and edit the generated @file{Makefile}! This makes it impossible for someone else to later reconfigure the package. @item Please document your changes to the source package so that future package maintainers know what has been changed. To do this, include a description of your changes in the @file{debian.README} (which, as described above, should already contain authorship and copyright information!) and include relevant information such as your name, electronic mail address, date, etc. The @file{debian.README} file should also document any `unusual' packages which must be installed for this one to compile. @item If changes to the source code are made that are applicable to Linux systems or systems in general please try to get them included in the upstream version of the package by supplying the upstream authors with the changes in whatever form they prefer. If changes to the source code are made, please use a @file{define}. If they are changes required to compile or function under Linux in general, use @file{LINUX}. If it is a cosmetic or functional change, use @file{DEBIAN}. @item Create the source package using @file{tar}, and use @file{gzip -9} to compress it. Source packages should be named in the form <@i{package}>-<@i{version}>.tar.gz---for example, @file{fileutils-3.9-3.tar.gz}. NB, here @code{<@i{version}>} is the full Debian version number, in the form @code{<@i{original_version}>-<@i{debian_revision}>} (see below), but the tarfile should unpack into a directory named @code{<@i{package}>-<@i{original_version}>} (again, see the section below on version numbering). @item Create the unified context diff against the original package using @file{diff -uNr}, and use @file{gzip -9} to compress it. Diffs should be named in the form <@i{package}>-<@i{version}>.diff.gz---for example, @file{fileutils-3.9-3.diff.gz}. @end itemize Please note that the package and patch filenames do @emph{not} need to fit in MS-DOS 8+3. They will be made available under an alternative 8+3 name in the archive by the archive maintainer, using a symlink. @node Binary Package, Control Files, Source Package, Top @unnumbered Binary Package The @file{binary} target of the source package @file{debian.rules} file should do the following (see the sample @file{debian.rules} for an implementation that you are free to modify and use in your own packages, of course): @itemize @bullet @item Create an empty directory in the top-level directory of the source package (deleting it first, if necessary), and install the files belonging to this package in that directory. For example, the directory could be called @file{debian-tmp} and would probably contain directories @file{debian-tmp/usr/bin}, @file{debian-tmp/usr/lib}, etc. (@file{debian-tmp} is the name traditionally used, and it is used in the sample @file{debian.rules} file, so we will use that name in the Guidelines.) @item Make sure that all the files under @file{debian-tmp} have the correct ownerships and permissions (@pxref{Package Content}, for more information about file locations, ownerships, and permissions.) @item Create a subdirectory of @file{debian-tmp} called @file{DEBIAN}. This directory contains the package control information, including at the very least the master information file named @file{control}. The next section describes the semantics and syntax of the files required and allowed here. @item Run @file{dpkg} to create the binary package, using something like @smallexample dpkg --build debian-tmp @end smallexample This will create a file called @file{debian-tmp.deb}, from the @file{debian-tmp} directory. You should rename this file to @file{../<@i{package}>-<@i{version}>.deb} after it is built. After the @file{binary} target has done all this, the @file{<@i{package}>-<@i{version}>.deb} file in the parent directory is the binary distribution. This file may be distributed and installed on any Debian Linux system with @file{dpkg} in the same manner and using the same methods as all packages are installed to the system. @item If a single source package corresponds to several binary packages, there should usually be a @file{debian.rules} file with a single @file{binary} target that builds all the binary packages involved and move all packages to the parent directory of that containing the source package. In this case, you should choose binary package names which are meant to make clear the close relationship between the binary packages and which source package the binary packages came from (for example, the @file{texinfo} source package build two binary packages: @file{texidoc} and @file{texinfo}). You should place the appropriate binary package name in the @file{Package} field of the control file (not the source package name), and you should consider whether the other binary packages that come from the same source tree should be mentioned in the @file{Depends}, @file{Recommends} or @file{Suggests} fields. You should put the source package name in the @file{Source} field. You should retain the source package version numbering in the @file{Version} field, if possible---the version number should be the same for the Debianised source tree and all the binary packages generated from it. It is more important, though, that the version numbers sort correctly. See below for details of version numbers. @end itemize @node Control Files, Appendix, Binary Package, Top @unnumbered Control Files Each binary package contains, in addition to the files that comprise the actual package, a set of text files that control how @file{dpkg} installs, configures, upgrades, removes, etc. the package. These files are called @dfn{control files}. When creating the package, the control files should placed in a directory called @file{DEBIAN}, as described earlier (@pxref{Binary Package}, for further information). The control information files are: @table @code @item control The master package control information file. @item conffiles A list of package configuration files. @item preinst The package pre-installation script. @item postinst The package post-installation script. @item prerm The package pre-removal script. @item postrm The package post-removal script. @end table Of these, only @file{control} is required. The various installation scripts, and the configuration files list, will only be used if they are present. @menu * control:: * conffiles:: * Installation and Removal Scripts:: * Dependencies and Conflicts:: * Package Classification Fields:: @end menu @node control, conffiles, Control Files, Control Files @unnumberedsec control The @file{control} file contains a number of fields. Each field begins with a field name, such as @file{Package} or @file{Version} (case insensitive), followed by a colon and optionally some spaces or tabs (a single space is conventional). Then comes the body of the field, which may be several lines long; each continuation line must start with at least one space or tab. (These are the same rules as apply to RFC822 mail headers.) Blank lines are not permitted in the control file. The required fields in the control file are the following: @table @code @item Package The name of the package. @item Description The description of the package. How to write an extended and more usefull description field can be found in @pxref{How to write the Description control file field}. @item Maintainer The name and e-mail address of the maintainer of the package. @item Version The version number in the format @code{<@i{original_version}>-<@i{debian_revision}>}. @end table Each field has a particular format and meaning for the package installation tools. The value of @file{Package} should be the name of the package. Package names must start with an alphanumeric, must be at least two characters, and may contain only alphanumerics and the characters - + . (that is, hyphen, plus, stop) @footnote{The characters @@ : = % _ (at, colon, equals, percent and underscore) used to be legal and are still accepted when found in a package file, but may not be used in new packages}. They are sort of case sensitive - please try to get the case right first time. The @code{Maintainer} field should be in the form @smallexample Joe J. Bloggs @end smallexample @noindent Note that this will not be useable as an email address if the name given contains full stop characters, because of a silly restriction in the Internet mail standards. If you want to use this as an email address in a program you should check for full stops and change the string to the form @code{jbloggs@@foo.com (Joe J. Bloggs)} if you find any. The @code{Version} field should be the version number of the package. For most packages which are not written specifically for Debian, this should be in the form @smallexample Version: <@i{original_version}>-<@i{debian_revision}> @end smallexample @noindent where @file{<@i{original_version}>} is the original package version number in whatever form the original package uses and @file{<@i{debian_revision}>} indicates which ``debianisation'' this is (this should usually be a plain number or perhaps a two numbers separated by a full stop, and should be incremented each time the package is changed or updated). Packages which are written specifically for Debian do not have a @i{debian_revision}, and their version number should simply be @i{version} (which should not contain any hyphens, to avoid confusion). There is an ordering imposed on version numbers, described in @file{version-ordering.txt}. This ordering is designed to `do the right thing' in most circumstances; if your package has an version number in an unusual format you may need to reformat it somewhat to get the ordering right. This is important because @file{dpkg} is (for example) reluctant to downgrade packages. The optional fields in the control file are the following: @table @code @item Depends The names of prerequisite packages. @item Recommends The names of related, recommended packages. @item Suggests The names of related, optional packages. @item Conflicts The names of packages which conflict with this package. @item Provides The names of virtual packages which this package provides. @item Priority The `priority' of the package, as shown and used by @file{dselect}. @item Section The `section' of the package, as shown and used by @file{dselect}, and used as a location for the package in the distribution. @item Essential A boolean field used by the base packages. @item Pre-Depends Used by base packages to ensure that (for example) shared libraries are present before they are upgraded. This feature is for expert use only. @item Source Gives the name of the source package when several binary packages are generated from a single source tree. @end table @noindent See below for details of the semantics and syntax of these fields. Most packages will need at least a @code{Depends} field. An example of a @file{control} file would be: @smallexample Package: smail Version: 3.1.29.1-13 Maintainer: Ian Jackson Recommends: pine | mailx | elm | emacs | mail-user-agent Suggests: metamail Depends: cron, libc5 Conflicts: sendmail Provides: mail-transport-agent Description: Electronic mail transport system. Smail is the recommended mail transport agent (MTA) for Debian. . An MTA is the innards of the mail system - it takes messages from user-friendly mailer programs and arranges for them to be delivered locally or passed on to other systems as required. . In order to make use of it you must have one or more user level mailreader programs such as elm, pine, mailx or Emacs (which has Rmail and VM as mailreaders) installed. If you wish to send messages other than just to other users of your system you must also have appropriate networking support, in the form of IP or UUCP. @end smallexample In this case, @file{mail-user-agent} is a virtual package representing any user mailer program; the actual package names @file{pine} is quoted for the reasons described in @file{dependency-ordering.txt}, and the others because older versions of those packages do not have the appropriate @file{Provides} field. @node conffiles, Installation and Removal Scripts, control, Control Files @unnumberedsec conffiles The contents of @file{conffiles} is simply a list of configuration files in the package. When installing the package, @file{dpkg} uses an intelligent method to update these files. This will ensure that package-specific configuration files are not overwritten when a package is upgraded, unless the user wishes the installation tools to do so. Typically, files listed in conffiles are package-specific configuration files, which (according to the Linux Filesystem Standard) are stored in @file{/etc}. For example, the @code{sendmail} package may contain the file @file{/etc/sendmail.cf}, which we do not wish to overwrite automatically when the user upgrades the sendmail package. Only those files listed in @file{DEBIAN/conffiles} will be updated intelligently when a package is upgraded; all other files in the package will be overwritten by the upgrade process. Configuration files which will be functional as shipped and will probably need little or no local editing should simply be listed the @file{conffiles} file; in this case you need read no further. For packages whose configuration files will need modification on most systems there are two sensible approaches. Which one is chosen depends on how hard the configuration problem is and how much time the package maintainer has available. One option is for you to ship a minimal `best-effort' file in @file{/etc}, and list the file in @file{conffiles}. This will mean that the user will have to go and edit the file themselves to get the package to work properly, of course. The next time they upgrade the package, if you haven't changed the file version, their old file will be left in place. If you have modified your version then the user will get a prompt asking them which version of the file they want, theirs or yours. They will then usually have to resolve the discrepancies manually. The other option is to be preferred, if you can do it: do not put a copy of the configuration file in the package at all. Instead, you check in the postinst whether the file exists, and if it doesn't you prompt the user for the information you need to create a good one. This is obviously harder work. You also have to remember that you will have to keep up with your package's changes: if you discover a bug in the program which generates the configuration file, or if the format of the file changes from one version to the next, you will have to arrange for the postinst script to do something sensible---usually this will mean editing the installed configuration file to remove the problem or change the syntax. You will have to do this very carefully, since the user may have changed the file, perhaps to fix the very problem that your script is trying to deal with---you will have to detect these situations and deal with them correctly. If you do go down this route it's probably a good idea to make the program that generates the configuration file(s) a separate program in @file{/usr/sbin}, by convention called @i{package}@code{config}, and then run that if appropriate from the post-installation script. The @i{package}@code{config} program should not unquestioningly overwrite an existing configuration---if its mode of operation is geared towards setting up a package for the first time (rather than any arbitrary reconfiguration later) you should have it check whether the configuration already exists, and require a @code{--force} flag to overwrite it. @file{conffiles} should almost certainly list all the files contained in your package in the @file{/etc} directory. There may also be other files somewhere that the user is expected to edit, which should also be included. Note, however, that the FSSTND specifies that configuration files must be in @file{/etc}. No Debian package should contain configuration files in @file{/usr/etc}, and all programs should refer to configuration files in @file{/etc}. @noindent For example, the TCP/IP package might use a conffiles which contains @smallexample /etc/init.d/netbase /etc/gateways /etc/protocols /etc/services /etc/hosts.allow /etc/hosts.deny /etc/rpc @end smallexample @noindent and so on; the files @smallexample /etc/hosts /etc/inetd.conf /etc/host.conf /etc/networks /etc/resolv.conf @end smallexample @noindent might be generated by an interactive configuration program, and would then not be included in the package or listed in the @file{conffiles}. @node Installation and Removal Scripts, Dependencies and Conflicts, conffiles, Control Files @unnumberedsec Installation and Removal Scripts The scripts @file{preinst}, @file{postinst}, @file{prerm}, and @file{postrm} are optional (Bash or Perl) scripts. As the names would indicate, if these scripts exist, they will be executed before installing the package, after installation, before package removal, and after removal, respectively. They are given arguments which indicate the precise situation and action being performed---see @pxref{Maintainer script arguments and how dpkg does things} for details of exactly when each of the scripts is invoked and what its arguments are. Extra arguments and situations may be added later, so you should not test the number of arguments to your script to determine the situation, and you should choose the sense of your `if it is this then do this otherwise do that' tests carefully. These scripts can be used to perform any site-specific package configuration. Because the scripts will be exectued by the dpkg front-end, it is guaranteed that the scripts will be executed interactively. User input from the scripts should be read from standard input, not the user's terminal. Similarly, output should be sent to standard output. If your maintainer scripts need to prompt for passwords and/or do @i{full-screen} interaction should do these things to and from @file{/dev/tty}, since @file{dpkg} will at some point redirect scripts' standard input and output so that it can log the installation process. Likewise, because these scripts may be executed with standard output redirected into a pipe for logging purposes, Perl scripts should set unbuffered output by setting @code{$|=1} so that the output is printed immediately rather than being buffered. The scripts must be idempotent, and they must clean up after themselves properly. Ie, they must do the right thing if run multiple times, even if previous runs failed halfway through. This is so that if any errors occur, or if the @file{dpkg} run is interrupted, the user can recover by rerunning @file{dpkg}, and/or by upgrading to a new version and then rerunning the failed operation. These scripts should avoid producing output which it is unnecessary for the user to see and should rely on @file{dpkg} to stave off boredom on the part of a user installing many packages. This means, amongst other things, using the @file{--quiet} option on @file{install-info}. Packages should try to minimise the amount of prompting they need to do, and they should ensure that the user will only every be asked each question once. This means that packages should try to use appropriate shared configuration files (such as @file{/etc/papersize} and @file{/etc/news/server}), rather than each prompting for their own list of required pieces of information. It also means that an upgrade should not ask the same questions again, unless the user has used @code{dpkg --purge} to remove the package's configuration. The answers to configuration questions should be stored in an appropriate place in @file{/etc} so that the user can modify them, and how this has been done should be documented. If a package has a vitally important piece of information to pass to the user (such as "don't run me as I am, you must edit the following configuration files first or you risk your system emitting badly-formatted messages"), it should display this in the @file{postinst} script and prompt the user to hit Return to acknowledge the message. Copyright messages do not count as vitally important (they belong in @file{/usr/doc/copyright}; neither do instructions on how to use a program (these should be in on line documentation, where all the users can see them). They should return a zero exit status for success, or a nonzero one for failure. Note that if a script is a @code{#!/bin/sh} script it should probably start with @code{set -e}, to avoid continuing after errors---see @file{bash}(1) for details. Perl scripts should check for errors when making calls such as @code{open}, @code{print}, @code{close}, @code{rename} and @code{system}. If these scripts exist they should be left in the @file{DEBIAN} directory with execute permission enabled and should contain an appropriate @code{#!} line, such as @code{#!/bin/bash} for a @code{bash} script or @code{#!/bin/perl} for a Perl script (see above). @node Dependencies and Conflicts, Package Classification Fields, Installation and Removal Scripts, Control Files @unnumberedsec Conflicts, Depends, Suggests, Recommends and Provides The @file{Depends} field lists packages that are required for this package to provide a significant amount of functionality. The package maintenance software will not allow a package to be installed without also installing packages listed in its @code{Depends} field, and will run the @code{postinst} scripts of packages listed in @code{Depends} fields before those of the packages which depend on them, and run the @code{prerm} scripts before. Packages containing dynamically-linked executable binaries (this includes almost all C programs) should include a @file{Depends} field which mentions the shared C library required for the program to run. For a.out binaries linked against @file{libc.so.4} the relevant package name is @file{libc} (for the a.out stable 0.93 tree) or @file{libc4} (for the unstable development 1.1 tree); for ELF binaries linked against @file{libc.so.5} the relevant package name is @file{libc5}. The @code{Recommends} field lists packages that would be found together with this one in all but unusual installations. The user-level package maintenance program @file{dselect} will warn the user if they select a package without those listed in its @code{Recommends} field. Note that @code{Recommends} fields do not currently have any implications for the order in which the maintainer scripts are run. The @code{Suggests} field lists packages that are related to this one and can perhaps enhance its usefulness, but without which installing this package is perfectly reasonable. The package maintenance software will not moan at the user for not selecting @code{Suggests} related packages, but may use the information in the @code{Suggests} field to assist the user during package selection. The syntax of @code{Depends}, @code{Recommends} and @code{Suggests} is a list of groups of alternative packages. Each group is a list of packages separated by vertical bar (or `pipe') symbols, @code{|}. The groups are separated by commas. Each package is a package name optionally followed by a version number specification in parentheses. A version number may start with a @code{>=}, in which case that version or any later will match, or @code{<=} for that version or any earlier version. A version number starting with a @code{>>} or @code{<<} will respectively match any later or earlier version. If a version number or a version number starting with @code{=} is specified an exact match is required. Commas are to be read as `AND', and pipes as `OR', with pipes binding more tightly. Versions of dpkg before 1.0.9 used @code{<} and @code{>} for @code{<=} and @code{>=} (these are still supported for backward compatibility), and did not support @code{<<} and @code{>>}. The @code{Conflicts} field lists packages that conflict with this one, for example by containing files with the same names (an example would be Smail vs. Sendmail). The package maintenance software will not allow conflicting packages to be installed. Two conflicting packages should each include a @code{Conflicts} line mentioning the other. The syntax of @code{Conflicts} is a list of package names (with optional version numbers), separated by commas (and optional whitespace). In the @code{Conflicts} field the comma should be read as `OR'. The @code{Provides} field lists the names of any `virtual packages' of which this packages is to be considered an instantiation. Virtual packages are used to allow packages to refer to a service they require (such as the availability of @file{/usr/sbin/sendmail}) without having to know the names of all the relevant packages. The virtual package names defined in @code{Provides} fields may be used in other packages' @code{Depends}, @code{Recommends}, @code{Suggests} and @code{Conflicts} fields. For more information about how to use virtual packages and which virtual package names to use read @pxref{Virtual dependencies} and @file{doc/package-developer/virtual-package-names-list.text}. The syntax of @code{Provides} is a list of package names separated by commas (and optional whitespace). @node Package Classification Fields, , Dependencies and Conflicts, Control Files @unnumberedsec Priority, Section and Essential The @code{Priority} and @code{Section} fields are used by @file{dselect} when displaying the list of packages to the user. There is no need to put them into a package, since these are usually set by the distribution maintainers in the @file{Packages} file. However, if a user installs a package which is not part of the standard distribution, or without downloading and updating from a new @file{Packages} file, the information about the priority and section of a package will be absent, and the @file{dselect} package listing will have the package listed under `unclassified'. It is permissible for a package to include @code{Section} or @code{Priority} fields to improve this; however, if you do this you should make sure you keep the information up to date so that users are not shown conflicting information. The @code{Section} field can also be used by the distribution maintainers as a suggestion about which section you think is most appropriate for your package. The values for the @code{Section} and @code{Priority} fields should be determined by the distribution maintainers; if you don't know what to put in them just leave them out. You can add them later, if you like, but remember that you'll then have to reissue your package if the distribution maintainers change the classification of your package. The @code{Essential} field should only appear in packages in the installation's base system. If it is set to @code{yes} then @file{dpkg} will not remove the package even if asked to, and will make certain minor modifications to its installation procedures. The only other legal value is @code{no}, which is equivalent to the absence of the field. @appendix @node Appendix, , Control Files, Top @unnumbered Appendix @comment node-name, next, previous, up @menu * configuration files -- /etc/skel vs /usr/doc/examples:: * How to write the Description control file field:: * Configuration of init:: * Maintainer script arguments and how dpkg does things:: * Mail processing packages:: * Virtual dependencies:: @end menu @node configuration files -- /etc/skel vs /usr/doc/examples, How to write the Description control file field, Appendix, Appendix @comment node-name, next, previous, up @unnumberedsec configuration files -- /etc/skel vs /usr/doc/examples There seems to be a certain amount of confusion about @file{/etc/skel} and @file{/usr/doc/examples}. The most important thing to remember is the following: Files in @file{/etc/skel} will @emph{automatically} be copied into @emph{new} user accounts by @file{adduser}. They should not be referenced there by any program. Files in @file{/usr/doc/examples} should not be installed automatically. Therefore, if the program in question need a dotfile to exist in advance in @file{$HOME} to work @emph{sensibly} that dotfile should be installed in @file{/etc/skel} (and listed in conffiles; @pxref{conffiles}). However, programs that require dotfiles in order to operate sensibly (dotfiles that they do not create themselves automatically, that is) are a bad thing, and that programs should be configured by the Debian default installation as close to normal as possible. Therefore, if a program in a Debian package needs to be configured in some way in order to operate sensibly that configuration should be done in a site-wide global configuration file elsewhere in @file{/etc} (and that file should be listed in conffiles). Only if the program doesn't support a site-wide default configuration should a default per-user file be placed in @file{/etc/skel} (and listed in conffiles; @pxref{conffiles}). The idea is as follows: The sysadmin should ideally not have to do any configuration other than that done @w{(semi-)}automatically by the postinst script. However, if they wish to change their configuration themselves (because the configuration they want is beyond the scope of the autoconfiguration, or because the autoconfiguration doesn't exist yet, or because they just want to do it themselves for any reason) then @file{/usr/doc/examples} exists as @emph{documentation} for their benefit. The only time these files should be read are by the sysadmin using their favourite editor or pager, or @emph{perhaps} (in very complex packages) by the postinst as a template to build on or modify. @file{/etc/skel} is part of the @emph{implementation} of this configuration. It contains the files that are copied into new user accounts. It should probably be as empty as we can make it. Examples: @table @code @item .profile @file{/etc/skel} should not contain a @file{.profile} file. Anything that needs to be done there should be done in @file{/etc/profile}. Anything that should not go in @file{/etc/profile} (users can't avoid running @file{/etc/profile}) probably should not be in the default configuration. bash has generally good default behaviour. @item .bash_logout Likewise, bash functions perfectly happily without a @file{.bash_logout}, so none should be provided, since anything in it is a deviation from the sensible default behaviour. @item .xsession @file{/etc/skel} should not contain a @file{.xsession}. @file{xdm}'s system-wide startup file @file{/usr/lib/X11/xdm/Xsession} supports a system-wide default user configuration (which should probably be @file{/etc/X11/Xsession} or some such) which may be overridden by @file{.xsession} in the user's home directory. Therefore there is no need for a @file{.xsession} to be installed by default and none should be provided. Instead, a sensible @file{/etc/X11/Xsession} should be provided, and if desired this can be used as a template by users who wish to install their own configuration, or alternatively a more comprehensive example with much commented-out interesting stuff could be put in @file{/usr/doc/examples}. If the sysadmin wishes to change the system-wide default they should probably do this by editing @file{/etc/X11/Xsession} rather than creating the file in @file{/etc/skel}, because the former will affect all user accounts that haven't explicitly overridden things by creating their own file while the latter will only affect new accounts. All the configuration necessary for a program to function should be provided. Therefore sysadmins will not need to go through @file{/usr/doc/examples} while editing configuration files in @file{/etc} except in extreme cases (like INN) where the configuration was too difficult to do automatically. @item site-wide defaults Site-wide defaults should not go in @file{/etc/skel}. In the case of twm, for example, the system-wide default should be in @file{/etc/X11/system.twmrc}. (The default location for this in X11R5, btw, is in @file{/usr/lib/X11} somewhere, but we can't put it on @file{/usr} because of CDROM distributions, etc - hence the FSSTND's mandate to put configuration files in @file{/etc}.) @item .twmrc There should be no @file{.twmrc} file in @file{/etc/skel}. You can have one in @file{/usr/doc/examples} if you @emph{like}, but why bother if @file{system.twmrc} is a good example (and indeed is the one the user is using before they create their own)? @item m4 @file{/usr/doc/examples} isn't mainly for example @emph{configuration files}. It's for any kind of example file distributed with a package. For example, GNU m4 comes with a whole pile of example m4 macro scripts, which is exactly what @file{/usr/doc/examples} is for. @end table Summary Files that should be installed in new user accounts should be in @file{/etc/skel}, as that will ensure that they @emph{are} installed in new user accounts! However, we should try to avoid the need for this. @file{/usr/doc/examples} is just what it says: documentation in the form of examples. If a sysadmin is required to go and read these files for their system to work they should be told about it. For example, here is what the Smail postinst script says right at the start: @smallexample I can do certain kinds of automatic configuration of your mail system, by asking you a number of questions. Later you may to confirm and/or correct your answers. In any case, comprehensive information on configuring Smail is in smail(5) and in /usr/doc/examples/smail and /usr/doc/smail-admin-guide. @end smallexample @node How to write the Description control file field, Configuration of init, configuration files -- /etc/skel vs /usr/doc/examples, Appendix @unnumberedsec How to write the Description control file field The format of the @code{Description} field is as follows: @smallexample Description: @end smallexample The extended description has several kinds of line: @itemize @bullet @item Those starting with a single space are part of a paragraph. Successive lines of this form will be word-wrapped when displayed. The leading space will usually be stripped off. @item Those starting with two or more spaces. These will be displayed verbatim. If the display cannot be panned horizontally the displaying program will linewrap them `hard' (ie, without taking account of word breaks). If it can they will be allowed to trail off to the right. None, one or two initial spaces may be deleted, but the number of spaces deleted from each line will be the same (so that you can have indenting work correctly, for example). @item Those containing a single space followed by a single full stop character. These are rendered as blank lines. This is the @emph{only} way to get a blank line - see below. @item Those containing a space, a full stop and some more characters. These are for future expansion. @emph{Do not} use them. @end itemize IMPORTANT and not so important TIPS: @itemize @bullet @item @emph{Always} start extended description lines with at least @emph{one} whitespace character. Fields in the control file and in the Packages file are separated by field names starting in the first column, just as in RFC822. Forgetting the whitespace will cause @file{dpkg-deb} (>=0.93.23) to produce a syntax error when trying to build the package. If you force it to build anyway @file{dpkg} will refuse to install the resulting mess. @item @emph{Do not} include any completely @emph{empty} lines. These separate different records in the Packages file, and are forbidden in control files. See the previous paragraph for what happens if you get this wrong. @item The single line synopsis should be kept brief - certainly under 80 characters. @file{dselect} displays the @emph{first 49} characters if you're using an 80-column terminal. @item Do not include the package name in the synopsis line. The display software knows how to display this already, and you do not need to state it. Remember that in many situations the user may only see the synopsis line - make it as informative as you can. @item The extended description should describe what the package does and how it relates to the rest of the system (in terms of, for example, which subsystem it is which part of). @item Put important information first, both in the synopis and extended description. Sometimes only the first part of the synopsis or of the description will be displayed. You can assume that there will usually be a way to see the whole extended description. @item You may include information about dependencies and so forth in the extended description, if you wish. @item Do not use tab characters. Their effect is not predictable. @end itemize Example control file for Smail: @smallexample Package: smail Version: 3.1.29.1-13 Maintainer: Ian Jackson Recommends: pine | mailx | elm | emacs | mail-user-agent Suggests: metamail Depends: cron, libc5 Conflicts: sendmail Provides: mail-transport-agent Description: Electronic mail transport system. Smail is the recommended mail transport agent (MTA) for Debian. . An MTA is the innards of the mail system - it takes messages from user-friendly mailer programs and arranges for them to be delivered locally or passed on to other systems as required. . In order to make use of it you must have one or more user level mailreader programs such as elm, pine, mailx or Emacs (which has Rmail and VM as mailreaders) installed. If you wish to send messages other than just to other users of your system you must also have appropriate networking support, in the form of IP or UUCP. @end smallexample @node Configuration of init, Maintainer script arguments and how dpkg does things, How to write the Description control file field, Appendix @unnumberedsec Configuration of init The @file{/etc/init.d} directory contains the scripts executed by init(8) when init state (or "runlevel") is changed. This includes the boot process, when the multi-user state begins. Several of these scripts are included with init and are intended to be executed @emph{once}, usually at boot time. An example is @file{/etc/init.d/boot}, which is executed at boot time to check and mount file systems, activate swap, load kernel modules, etc.--everything that needs to be done before the multi-user state begins. @file{/etc/init.d} also contains the scripts that are executed when entering runlevel 0 (halt), runlevel 1 (single-user) and runlevel 6 (reboot). Packages can (and should) place scripts in @file{/etc/init.d} to start or stop services at boot time or during a change of runlevel. These scripts should be named @file{/etc/init.d/}, and they should accept one of two arguments: "start", which starts the services, or "stop", which stops the services. These scripts should ensure that they will behave sensibly if invoked with "start" when the service is already running, or with "stop" when it isn't---the best way to achieve this is often to use @file{start-stop-daemon}. This script should not fail obscurely when the configuration files remain but the package has been removed, as the default in dpkg is to leave configuration files on the system after the package has been removed. Only when it is executed with the `--purge' option will dpkg remove configuration files. Therefore, you should include a `test' statement at the top of the script, like this: @smallexample test -f || exit 0 @end smallexample These scripts should be referenced, when appropriate, by symbolic links in the @file{/etc/rc?.d} directories, as below. When changing runlevels, init looks in the directory @file{/etc/rc.d} for the scripts it should execute, where is the runlevel that is being changed to. Please note that the "scripts" in @file{/etc/rc?.d} are not actually scripts; they are symbolic links, referencing actual scripts in @file{/etc/init.d}. For simplicity, we refer to them as "scripts". First, the scripts prefixed with a "K" are executed, followed by the scripts prefixed with an "S". The "K" scripts are responsible for killing certain services and the "S" scripts for starting certain services upon @emph{entering} the runlevel. For example, if we are changing from runlevel 2 to runlevel 3, init will first execute all of the "K" prefixed scripts it finds in @file{/etc/rc3.d} (to kill services), and then all of the "S" prefixed scripts it finds in @file{/etc/rc3.d} (to start services). The "K" scripts will execute the file it references with an argument of "stop", and the "S" scripts will execute this file with an argument of "start". After the "K" or "S" prefix, there should be a number specified, and this number should be between 00 and 99. The number determines the order in which the scripts are run. For example, the "K20" scripts will be executed before the "K30" scripts. You can use this number to make sure that a certain service is started before another. For example, on some machines, the program @file{setserial} may need to properly set an IRQ before the @file{ppp} program uses a modem to connect to a network. In this case, the script that runs @file{setserial} should have a lower number than the script that starts @file{ppp} so that it runs first: @smallexample @file{/etc/rc2.d/S10setserial} @file{/etc/rc2.d/S20ppp} @end smallexample If it does not matter when or in which order the script is run, use the number "20". If it does, then you should talk to the maintainer of the @code{sysvinit} package or post to @code{debian-devel}, and they will help you choose a number. In Debian Linux, we try to ship our software in as much of a "default" state as possible. Therefore, unless there is a good reason for doing differently, we ask that you start the services in each of the multi-user state runlevels (2, 3, 4, and 5) and stop them in the halt runlevel (0), the single-user runlevel (1) and the reboot runlevel (6). The system administrator will have the opportunity to customize runlevels by simply adding, moving, or removing the symbolic links in @file{/etc/rc?.d}. This is why we default to running everything in the multi-user state--a reasonable default--and the administrator can easily customize init to be as complex and sophisticated as he or she wants it to be beyond this. We provide a script, @file{update-rc.d}, to make it easier for package maintainers to arrange for the proper creation and removal of @file{/etc/rc?.d} symbolic links from their postinst and postrm scripts. You should use this script to make changes to @file{/etc/rc?.d} and @emph{never} include any @file{/etc/rc.?.d} symbolic links in the actual archive. @itemize @bullet @item In the postinst script, you need only do the following to setup @file{/etc/rc?.d}. You should redirect standard output to @file{/dev/null}, as @file{update-rc.d} produces insignificant output: @smallexample update-rc.d default >/dev/null @end smallexample where is the name of the file as it appears in @file{/etc/init.d}. It will use the default number of "20", as mentioned above. If you need to use a different number, you can specify it after "default": @smallexample update-rc.d default 30 >/dev/null @end smallexample @item In the postrm script, you need only do the following @emph{if and only if} it is called with the `purge' argument: @smallexample if [ purge = "$1" ] then update-rc.d remove >/dev/null fi @end smallexample @end itemize @unnumberedsubsec Important Note: @emph{Do not} include the @file{/etc/rc?.d/*} symbolic links in the archive! @emph{This will cause problems!} You should create them with update-rc.d, as above. @emph{Do not} include the @file{/etc/rc?.d/*} symbolic links in conffiles! @emph{This will cause problems!} @emph{Do}, however, include the @file{/etc/init.d} scripts in conffiles. @unnumberedsubsec Example: The process accounting package wants to make sure that process accounting is started at boot time and that it is stopped before the system is halted, enters the single-user state, or is rebooted (so that the @file{/var} file system can be properly unmounted). It puts a script that does this in @file{/etc/init.d}, naming the script appropriately "acct". This script accepts one of two arguments: either "start", which starts process accounting, or "stop", which stops it. To ensure that it does not fail obscurely when the configuration files remain but the package has been removed, we include a `test' statement at the top of the script: @smallexample #! /bin/sh # # Start process accounting. . /etc/init.d/functions test -f /usr/sbin/accton || exit 0 case "$1" in start) echo "Starting process accounting" /usr/sbin/accton /var/account/pacct ;; stop) echo "Stopping process accounting" /usr/sbin/accton ;; *) echo "Usage: /etc/init.d/acct @{start|stop@}" exit 1 esac exit 0 @end smallexample You may find a skeletal script from which to base your @file{/etc/init.d} scripts in @file{/etc/init.d/skeleton}. We want to stop then (re)start process accounting when entering a multi-user state--runlevels 2, 3, 4, and 5--and we want to stop it when leaving such a state--runlevels 0 (halt), 1 (single) and 6 (reboot). These are good defaults, and we accomplish this by including the following in the postinst: @smallexample update-rc.d acct default >/dev/null @end smallexample When the user removes the acct packages with the `--purge' option, we want to make sure the @file{/etc/rc?.d} symbolic links are properly removed, so we include the following in the postrm: @smallexample update-rc.d acct remove >/dev/null @end smallexample Otherwise, the @file{/etc/rc?.d} symbolic links will remain on the system along with @file{/etc/init.d/acct} script. @node Maintainer script arguments and how dpkg does things, Mail processing packages, Configuration of init, Appendix @unnumberedsec Maintainer script arguments and how dpkg does things This appendix describes exactly how maintainer scripts are called, with what arguments, in what order, and what @file{dpkg} does in between. In all cases version numbers are -, if the package has both, or just . @code{upgrade} is used even when the new version number looks lower than the old. If there is no appropriate version then the argument may be the empty string (or, in versions of dpkg before 1.2.1, @code{}). @unnumberedsubsec Summary @smallexample install install upgrade abort-upgrade configure abort-upgrade abort-remove in-favour abort-deconfigure \ in-favour removing remove upgrade failed-upgrade remove in-favour deconfigure \ in-favour \ removing remove purge upgrade failed-upgrade abort-install abort-install abort-upgrade disappear @end smallexample @unnumberedsubsec Details of unpack phase of installation or upgrade The procedure on installation/upgrade/overwrite/disappear (ie, when running @code{dpkg --unpack}, or the unpack stage of @code{dpkg --install}) is as follows. In each case if an error occurs the actions in are general run backwards - this means that the maintainer scripts are run with different arguments in reverse order. These are the `error unwind' calls listed below. @enumerate @item @noindent @enumerate a @item If a version the package is already installed, call @smallexample upgrade @end smallexample @item If this gives an error (ie, a non-zero exit status), dpkg will attempt instead: @smallexample failed-upgrade @end smallexample @noindent error unwind, for both the above cases: @smallexample abort-upgrade @end smallexample @end enumerate @item If a `conflicting' package is being removed at the same time: @noindent @enumerate a @item If any packages depended on that conflicting package and @code{--auto-deconfigure} is specified, call, for each such package: @smallexample deconfigure \ in-favour \ removing @end smallexample @noindent error unwind: @smallexample abort-deconfigure \ in-favour removing @end smallexample The deconfigured packages are marked as requiring configuration, so that if --install is used they will be configured again if possible. @item To prepare for removal of the conflicting package, call: @smallexample remove in-favour @end smallexample @noindent error unwind: @smallexample abort-remove in-favour @end smallexample @end enumerate @item @noindent @enumerate a @item If the package is being upgraded, call @smallexample upgrade @end smallexample @item otherwise, if the package had some configuration files from a previous version installed (ie, it is in the conffiles-only state): @smallexample install @end smallexample @item otherwise (ie, the package was completely purged): @smallexample install @end smallexample @noindent error unwind versions, respectively: @smallexample abort-upgrade abort-install abort-install @end smallexample @end enumerate @item The new package's files are unpacked, overwriting any that may be on the system already, for example any from the old package or from another package (backups of the old files are left around, and if anything goes wrong dpkg will attempt to put them back as part of the error unwind). @item @noindent @enumerate a @item If the package is being upgraded, call @smallexample upgrade @end smallexample @item If this fails, dpkg will attempt: @smallexample failed-upgrade @end smallexample @noindent error unwind, for both cases: @smallexample abort-upgrade @end smallexample @end enumerate This is the point of no return - if dpkg gets this far, it won't back off past this point if an error occurs. This will leave the package in a fairly bad state, which will require a successful reinstallation to clear up, but it's when dpkg starts doing things that are irreversible. @item Any files which were in the old version of the package but not in the new are removed. @item The new file list replaces the old. @item The new maintainer scripts replace the old. @item Any packages all of whose files have been overwritten during the installation, and which aren't required for dependencies, are considered to have been removed. For each such package, @noindent @enumerate a @item dpkg calls: @smallexample disappear @end smallexample @item The package's maintainer scripts are removed. @item It is noted in the status database as being in a sane state, namely not installed (any conffiles it may have are ignored). Note that disappearing packages do not have their prerm called, because dpkg doesn't know in advance that the package is going to vanish. @end enumerate @item Any files in the package we're unpacking that are also listed in the file lists of other packages are removed from those lists. (This will lobotomise the file list of the `conflicting' package if there is one.) @item The backup files made at 4. are deleted. @item The new package's status is now sane, and recorded as `unpacked'. Here is another point of no return - if the conflicting package's removal fails we do not unwind the rest of the installation; the conflicting package is left in a half-removed limbo. @item If there was a conflicting package we go and do the removal actions, starting from point 2. of the removal, below. @end enumerate @unnumberedsubsec Details of configuration When we configure a package (this happens with @code{dpkg --install}, or with @code{--configure}), we first update the conffiles and then call: @smallexample configure @end smallexample No attempt is made to unwind after errors during configuration. @unnumberedsubsec Details of removal and/or configration purging @enumerate @item @smallexample remove @end smallexample @item The package's files are removed (except conffiles). @item @smallexample remove @end smallexample @item All the maintainer scripts except the postrm are removed. If we aren't purging the package we stop here. Note that packages which have no postrm and no conffiles are automatically purged when removed, as there is no difference except for the dpkg status. @item The conffiles and any backup files (@samp{~}-files, @samp{#*#} files, @samp{%}-files, .dpkg-@{old,new,tmp@}, etc.) are removed. @item @smallexample purge @end smallexample @item The package's file list is removed. @end enumerate No attempt is made to unwind after errors during removal. @node Mail processing packages, Virtual dependencies, Maintainer script arguments and how dpkg does things, Appendix @unnumberedsec Mail processing packages Debian packages which process electronic mail (whether mail-user-agents (MUA) or alternative mail-transport-agents (MTA)) @emph{must} make sure that they are compatible with the configuration decisions below. Failure to do this may result in lost mail, broken @code{From:} lines, and other serious brain damage! @itemize @bullet @item The mail spool is @file{/var/spool/mail} and the interface to send a mail message is @file{/usr/sbin/sendmail} (as per the FSSTND). The mail spool is part of the base and not part of the MTA package. @item Mailboxes are locked using the @file{.lock} lockfile convention, rather than fcntl, flock or lockf. @item Mailboxes are generally 660 @file{.mail} unless the user has chosen otherwise. A MUA may remove a mailbox (unless it has nonstandard permissions) in which case the MTA or another MUA must recreate it if needed. Mailboxes must be writeable by group mail. @item The mail spool is 2775 mail.mail, and MUA's need to be setgid mail to do the locking mentioned above (and obviously need to avoid accessing other users' mailboxes using this privilege). @item @file{/etc/aliases} is the source file for the system mail aliases (e.g. postmaster, usenet, etc.) - it is the one which the sysadmin and postinst scripts may edit. @item The convention of writing `forward to
' in the mailbox itself is not supported. Use a @file{.forward} file instead. @item The location for the @file{rmail} program used by UUCP for incoming mail is @file{/usr/sbin/rmail}, as per the FSSTND. Likewise, @file{rsmtp}, for receiving batch-SMTP-over-UUCP, is in @file{/usr/sbin/rsmtp} if it is supported. @item Smail is not using HoneyDanBer UUCP, whose uux apparently accepts -a and -g options. @item If you need to know what name to use (for example) on outgoing news and mail messages which are generated locally, you should use the file @file{/etc/mailname}. It will contain the portion after the username and @samp{@@} sign for email addresses of users on the machine (followed by a newline). @end itemize A package should check for the existence of this file. If it exists it should use it without comment @footnote{An MTA's prompting configuration script may wish to prompt the user even if it finds this file exists.}. If it does not exist it should prompt the user for the value and store it in @file{/etc/mailname} as well as using it in the package's configuration. The prompt should make it clear that the name will not just be used by that package. E.g., in the same situation the INN package says: @smallexample Please enter the `mail name' of your system. This is the hostname portion of the address to be shown on outgoing news and mail messages. The default is `$syshostname', your system's host name. Mail name [`$syshostname']: @end smallexample ($syshostname is the output of `hostname --fqdn'). @node Virtual dependencies, , Mail processing packages, Appendix @comment node-name, next, previous, up @unnumberedsec Virtual dependencies Virtual packages are in the same namespace as real packages, and may have the same name. The meaning of a virtual package in a dependency/conflicts list is exactly that of listing all the real packages which state that they are an instantiation of that virtual package. This is done with a new Provides field in the control file, with a syntax much like the Conflicts field. The idea is that we can have something like: @smallexample Package: elm Depends: mta Package: smail Provides: mta Conflicts: mta Package: sendmail Provides: mta Conflicts: mta @end smallexample @noindent The result is equivalent to elm having said @smallexample Package: elm Depends: smail | sendmail @end smallexample (There'll be a special case to say that a package may conflict with a virtual package which it provides - clearly ...) If there are both a real and a virtual package of the same name then the dependency may be satisfied (or the conflict caused) by either the real package or any of the virtual packages which provide it. This is so that, for example, supposing we have @smallexample Package: lout Optional: ghostview @end smallexample (this is a fictional example - the Lout package should not mention ghostview), and someone else comes up with a nice PostScript previewer, then they can just say @smallexample Package: marvelpostview Provides: ghostview @end smallexample and all will work in the interim (until, say, the Lout maintainer changes things). If a dependency or a conflict has a version number attached then only real packages will be considered to see whether the relationship is satisfied (or prohibited, for a conflict) - it is assumed that a real package which provides virtual package is not of the `right' version. If there is demand it can be arranged that a package which provides a virtual package may mention a version number, though this is unlikely to be helpful: @smallexample Provides: mta (2.0) @end smallexample If you want to specify which of a set of real packages should be the default to satisfy a particular dependency on a virtual package, you can simply list the real package as alternative before the virtual one: @smallexample Package: xbaseR6 Recommended: xsvga | x-server Provides: x-base, xr6shlib Package: xsvga Recommended: x-base Provides: x-server Package: x8514 Recommended: x-base Provides: x-server @end smallexample Virtual package names should generally not be used in the names of @file{/etc/init.d} scripts, configuration files, logfiles, and so on, so that several programs providing the same virtual package name can be installed. @bye