Let's say I want to install something big... (kde for example) but I'm doing it in a place with a very poor internet conection, so I want to stop it, and doing it later. But I don't want to start all over again. Can it be done?
Later when you have a better
connection you can just drop the -d and apt will download the
rest if needed and begin installing from the cache:
If you kill an apt-get while it's still in the stage of fetching packages then yes, it will resume fetching pretty much from where it left off - the archvies it has fetched so far will be kept in /var/cache/apt/archives.
This is the directory that gets cleaned up by
If you kill it after it's finished fetching and has started configuring/installing then you're in much deeper water and I wouldn't really want to try it ;)
Or, start the installation with GNU Screen. Just run
This also works for long-running command such as apt-get install [all of KDE]: just start the apt-get install command inside a screen window and press ^d. Then later, simply re-attach using
Screen has much more options:
Edit: Of course, the computer running