re: xdm crash

[Sidney Brooks]

I decided to reinstall the Debian package xdm since it wasn't working, 
using dpkg. When I tried, I got the error message:
unable to fill /var/lib/dpkg/updates/tmp.i with padding: No space left on 
device

This suggests that the new files that I downloaded were so large that they 
filled my hard disk. What command can I use to check the available space on 
the hard disk. I know how to do this with gnome, but I am stuck with run 
level 3, which is like dos.