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Package Removal
Here is what happens during a package removal.
1. dpkg calls prerm remove.
2. dpkg removes all of the package’s files, with the exception of the configuration files and configuration scripts.
3. dpkg executes postrm remove. All of the configuration scripts, except postrm, are removed. If you have not used the purge option, the process stops here.
4. For a complete purge of the package (command issued with dpkg --purge or dpkg -P), the configuration files are also deleted, as well as a certain number of copies (*.dpkg-tmp,
*.dpkg-old, *.dpkg-new) and temporary files; dpkg then executes postrm purge.
In some cases, a package might use debconf to require configuration information from you: the four scripts detailed above are then complemented by a config script designed to acquire that in- formation. During installation, this script defines in detail what questions debconf will ask. The responses are recorded in the debconf database for future reference. The script is generally exe- cuted by apt prior to installing packages one by one in order to group all the questions together at the beginning of the process. The pre- and post-installation scripts can then use this information to operate according to your wishes.
The debconf Tool The debconf tool was created to resolve a recurring problem in Debian. All Debian packages unable to function without a minimum of configuration used to ask ques- tions with calls to the echo and read commands in postinst shell scripts (and other similar scripts). This forced the installer to babysit large installations or updates in order to respond to various configuration queries as they arose. These manual inter- actions have now been almost entirely dispensed with, thanks to debconf.
The debconf tool has many interesting features: It requires the developer to specify user interaction; it allows localization of all the displayed strings (all translations are stored in the templates file describing the interactions); it provides different fron- tends for questions (text mode, graphical mode, non-interactive); and it allows cre- ation of a central database of responses to share the same configuration with several computers. The most important feature is that all of the questions can be presented in a row, all at once, prior to starting a long installation or update process. Now, you can go about your business while the system handles the installation on its own, without having to stay there staring at the screen, waiting for questions to pop up.
The debconf Tool The debconf tool was created to resolve a recurring problem in Debian. All Debian packages unable to function without a minimum of configuration used to ask ques- tions with calls to the echo and read commands in postinst shell scripts (and other similar scripts). This forced the installer to babysit large installations or updates in order to respond to various configuration queries as they arose. These manual inter- actions have now been almost entirely dispensed with, thanks to debconf.
The debconf tool has many interesting features: It requires the developer to specify user interaction; it allows localization of all the displayed strings (all translations are stored in the templates file describing the interactions); it provides different fron- tends for questions (text mode, graphical mode, non-interactive); and it allows cre- ation of a central database of responses to share the same configuration with several computers. The most important feature is that all of the questions can be presented in a row, all at once, prior to starting a long installation or update process. Now, you can go about your business while the system handles the installation on its own, without having to stay there staring at the screen, waiting for questions to pop up.