`disktool' is an XView program to monitor up to 64 filesystems
simultaneously and alert you when a particular filesystem is low on
space. disktool is set-up to "un-iconify" when a filesystem it is
monitoring has reached its' user-definable "critical threshold". A
unix command can also be initiated when this threshold is reached.
The command and un-iconifying can be repeated every so many polls,
configurable from the cmdline or from the Properties pop-up.
The properties pop-up is obtained by selecting any gauge with the
right mouse button. The middle mouse button has also been mapped to 
force a filesystem poll to update the displayed data.

`disktool' is a good sysadmin tool for monitoring diskfull situations
to avoid datafile corruption.

WWW: http://step.polymtl.ca/~coyote/xview_main.html