Rotation of system logs is no longer managed by the daily script. Apple, in their wisdom, have assigned this duty to newsyslog, run by launchd according to the com.apple.newsyslog daemon instructions.The default (as of 10.5.1) is that newsyslog is run by launchd at midnight every day. You might see where I am going with this one -- if your machine is off or asleep at this time, the rotation won't be run.Now launchd will run newsyslog when you wake your machine in the morning, but the newsyslog.conf file instructs newsyslog to only rotate the system.log within an hour of the allotted time, ie midnight. All other logs (eg ftp.log, ipfw.log etc) are set to rotate when they reach a certain size, but system.log has no size limit so could grow and grow...The easy solution is to change the following li...

	Read more at MacOsxHints
	feeds.macosxhints.com/~r/macosxhints/recent/~3/202783451/article.php