Difference between apt(itude) (auto)clean, … After understanding that `apt` is somehow an expansion of `apt-get` or an aggregation of several `apt-…` commands, I'm still confused how the different commands (especially `apt`, `apt-get`, `aptitude` and the subcommand(s) `autoclean`, `autoremove`, `clean`) do their job and which one fulfil my needs (fully deleting packages which I don't need any more after manually removing other packages).

`autoremove` is what you’re looking for: it removes automatically-installed packages which no longer have any dependencies. `apt autoremove` and `apt-get autoremove` are equivalent. `aptitude` doesn’t have an `autoremove` subcommand because it always removes such packages when they become candidates for removal ( _i.e._ auto-removable packages are removed along with the package whose removal causes them to become auto-removable).

Note that package installation and auto-removal isn’t symmetric in the default configuration; see How do recommends and suggests interact with apt-get dist-upgrade and apt-get autoremove? for details.

`clean` removes all downloaded `.deb` files from the package caches, and `autoclean` removes those which can no longer be downloaded. Both of these subcommands behave in the same way, with `apt`, `apt-get` and `aptitude`.