http://packages.debian.org/sid/developers-reference - - Maintainer scripts include the files debian/postinst, debian/ preinst, debian/prerm and More

http://packages.debian.org/sid/developers-reference - - Maintainer scripts include the files debian/postinst, debian/ preinst, debian/prerm and debian/postrm. These scripts take care of any package installation or deinstallation setup which isn't handled merely by the creation or removal of files and directories. The following instructions supplement the Debian Policy. Maintainer scripts must be idempotent. That means that you need to make sure nothing bad will happen if the script is called twice where it would usually be called once. Standard input and output may be redirected (e.g. into pipes) for logging purposes, so don't rely on them being a tty. All prompting or interactive configuration should be kept to a minimum. When it is necessary, you should use the debconfpackage for the interface. Remember that prompting in any case can only be in the configure stage of the postinst script. Keep the maintainer scripts as simple as possible. We suggest you use pure POSIX shell scripts. Remember, if you do need any bash features, the maintainer script must have a bash shebang line. POSIX shell or Bash are preferred to Perl, since they enable debhelper to easily add bits to the scripts. If you change your maintainer scripts, be sure to test package removal, double installation, and purging. Be sure that a purged package is completely gone, that is, it must remove any files created, directly or indirectly, in any maintainer script. If you need to check for the existence of a command, you shoulduse something like if [ -x /usr/sbin/install-docs ]; then ... If you don't wish to hard-code the path of a command in your maintainer script, the following POSIX-compliant shell function may help: pathfind() { OLDIFS="$IFS" IFS=: for p in $PATH; do if [ -x "$p/$*" ]; then IFS="$OLDIFS" return 0 fi done IFS="$OLDIFS" return 1 } You can use this function to search $PATH for a command name, passed as an argument. It returns true (zero) if the command was found, and false if not. This is really the most portable way, since command -v, type, and which are not POSIX. While which is an acceptable alternative, since it is from the required debianutils package, it's not on the root partition. That is, it's in /usr/bin rather than /bin, so one can't use it in scripts which are run before the /usr partition is mounted. Most scripts won't have this problem, though. 6.5.**Configuration management with debconf Debconf is a configuration management system which can be used by all the various packaging scripts (postinst mainly) to request feedback from the user concerning how to configure the package. Direct user interactions must now be avoided in favor of debconf interaction. This will enable non-interactive installations in the future. Debconf is a great tool but it is often poorly used. Many common mistakes are listed in the debconf-devel(7) man page. It is something that you must read if you decide to use debconf. Also, we document some best practices here. These guidelines include some writing style and typography recommendations, general considerations about debconf usage as well as more specific recommendations for some parts of the distribution (the installation system for instance). 6.5.1.**Do not abuse debconf Since debconf appeared in Debian, it has been widely abused and several criticisms received by the Debian distribution come from debconf abuse with the need of answering a wide bunch of questions before getting any little thing installed. Keep usage notes to what they belong: the NEWS.Debian, or README.Debian file. Only use notes for important notes which may directly affect the package usability. Remember that notes willalways block the install until confirmed or bother the user by email. Carefully choose the questions priorities in maintainer scripts. See debconf-devel(7) for details about priorities. Most questions should use medium and low priorities. 6.5.2.**General recommendations for authors and translators 6.5.2.1.**Write correct English Most Debian package maintainers are not native English speakers. So, writing properly phrased templates may not be easy for them. Please use (and abuse) [debian-l10n-english@ lists.debian.org] mailing list. Have your templates proofread. Badly written templates give a poor image of your package, of your work...or even of Debian itself. Avoid technical jargon as much as possible. If some terms sound common to you, they may be impossible to understand for others. If you cannot avoid them, try to explain them ( use the extended description). When doing so, try to balance between verbosity and simplicity. 6.5.2.2.**Be kind to translators Debconf templates may be translated. Debconf, along with its sister package po-debconf offers a simple framework for getting templates translated by translation teams or even individuals.
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