System.log and system.log.0.gz

[isolder]

Is one of these files the main log and the other a back up of the log?

Also, can I delete these two files? They'll be recreated right?

 

[blb]

system.log is the current logfile (and should be in use); system.log.N.gz are previous days' log files, which can be safely deleted. Since these are rotated daily (if your machine is on at 0315), they shouldn't be that large.