Deleting logs older than nnn days
From Tech-Wiki
In order to avoid running out of disk space, you can set to delete log files older than one year (you can adjust this value below) just edit your crontab and add:
0 0 1 1 * find $FWDIR/log/ -mtime +365 -exec rm -f {} \;
This way, on January 1st, it will delete the files from the previous year (not the one that has just ended :)