I had been running Ubuntu 14.04 for about a month without problems but when a program crashed (FlashGraphs if that is important) the computer froze, and I restarted. When I tried to log back in, after entering my password, the screen freezes on my background with nothing else showing up. I am able to log in to the guest session, where when I open it, I get the warning that root has 0 bytes remaining. I see that a file that had been created for FlashGraphs within my /var/tmp directory that is extremely large and composes the bulk of my space. The problem is that I don't know a way to delete that file from the guest session and I can't access my account since it freezes before I get to it.
You can clean up spurious large files in recovery mode, which doesn't require you to log in with your normal user account.
Boot your computer in Ubuntu's recovery mode. Mount the file system(s) as described in steps 8 and 9. In particular, mount
/var, if it's not part of the root file system. (If you don't know what that means, it probably doesn't apply to you.)
Enter and run the following commands to delete the content of
shopt -s dotglob rm -r /var/tmp/*
(If the shell doesn't understand
shopt, just leave it and skip to the next command.)
A more portable alternative would be:
find /var/tmp -mindepth 1 -delete
Reboot, e. g. with the command
On another note, I'm a bit confused, that the startup scripts don't take care of cleansing
/var/tmp during boot. Per the specification, applications mustn't expect anything in there to survive a reboot anyway. Or do these statements only apply to
/tmp? Maybe someone can clear that up in the comments or through an edit.