Well, even easier, use Bleachbit to clean up bash history and all other traces of trash, including Ubuntu Apt cache. Sometimes more than 1GB of space can be freed just by running Blachbit in user space and root mode.
On certain distros the -w switch is needed to write the cleansed state into memory, otherwise you may be left with the history -c mention in the bash. Also, use parcellite to view and clear any clipboard content, even if you're a Bleachbit user.
