If the disk is filling up, first find out which files it is, which will tell you which program(s) to check.
Tell us which distro+version you have
Code:
cat /etc/*release*
uname -a
Most (all?) will have a tool called logrotate
http://linux.die.net/man/8/logrotate, usually configured in /etc/logrotate.d, which will automatically cleanup your logs, depending on the cfg.