file system full help

[Noah]

I sometimes get reports of "file system full" but not accurately because when
viewing the drive with "df -k" I find there is adequate space on the drive. 
Usually this is casused by log files considered larger than the available
space on the /var directory.  I would like to see if this in fact the case.

Can somebody please remind me what commands I can use to troubleshoot this
current condition?

thanks in advance,

Noah