Topic: Cleaning up clogged root (system) partition
Disclaimer: I am no expert in Linux system management but I trust real experts will correct errors below.
Background:
Some time ago I suddenly had problems watching Flash video content and it turned out my root partition was very, very close to 100% full. See http://crunchbanglinux.org/forums/topic this-week/ I was lucky only watching Flash videos didn't work. It could have been much, much worse.
Manual cleaning up:
The reason the root partition was full was a very large number of .deb files in /var/cache/apt/archives and big log files in /var/log.
sudo apt-get autocleandeletes .deb files that are obsolete ("...can no longer be downloaded, and are largely useless." in the words of man apt-get.) This got my system back into normal behaviour but the root partition was still dangerously full.
sudo apt-get cleandeletes all .deb files from the cache. This made quite a difference in root partition space for me.
Let's move over to the log files in /var/log. If you, like me, never study these and don't know how to interpret their content you can delete all enumerated versions: dmesg.0, dmesg.1.gz etc. This also made quite a difference to my system. I now have close to 20% free space on my root partition.
Possible long-term options:
Putting /var on its own HD partition would stop run-away log files from freezing your system, I am told.
There is a program called logrotate that can be used for managing log files. Read on at man logrotate for more information. The puzzle to me here is it looks like syslog and kern.log are managed by logrotate but there is nothing on them in the config files for logrotate.
In the preferences of Synaptic one can choose the option "Delete downloaded packages after installation". If it does what it says -- I have not tested yet -- it should remove all .deb files after installation.
/Martin