All system admins will need to check, at some point, how much disk space is free on their systems. If the system is remote, or perhaps in a datacenter, you will need to run a shell command. the one you want is:
This basic command outputs the space in terms of 1 kilobyte chunks, which isn't very readable. to get a nicely formatted output, run this:
> du -h
Nice and easy huh? Now why not script it and put it into a cron job??