According to the
dpkg man page, a selection state of install means "The package is selected for installation". A selection state of deinstall means "The package is selected for deinstallation (i.e. we want to remove all files, except configuration files)".
What confuses me, and what I would like to clarify: After I remove a package, it is in the selection state deinstall. But it's already removed. How can something that is removed be in any state? And I did remove all files, I don't "want to remove" them.
Same for the install selection state: How can a package be "selected for installation" if it is already installed?
In the same vein, the man page of
dpkg-query differentiates between desired action and package status, which I understand to be the same as selection state and state, respectively. Most packages have a desired action of Install and a status of Installed. Again, what is this supposed to mean? Why do we desire installing a package that is already installed?
And the big question: Under which circumstances is this distinction between selection/desired state and normal state relevant at all?