Wicked Cool Shell Scripts

#55 Rotating Log Files

Users who don't have much experience with Unix can be quite surprised by how many commands, utilities, and daemons log events to system log files. Even on a computer with lots of disk space, it's important to keep an eye on the size of these files and, of course, on their contents too.

As a result, most sysadmins have a set of instructions that they place at the top of their log file analysis utilities, similar to the following:

mv $log.2 $log.3
mv $log.1 $log.2
mv $log $log.1
touch $log

If run weekly, this would produce a rolling one-month archive of log file information divided into week-size portions of data. However, it's just as easy to create a script that accomplishes this for all log files in the /var/log directory ...