log file rotation

[Nunners]

I'm using Plesk 8.2.1 Virtuozzo and have recently found that the log files are being allowed to grow in size, thus meaning the server was down for a good few days last week while I tried to work out what had happened.

The files in question are all in /var/log; and are auth.log, messages, syslog, mail.err and mail.info.

Could anyone suggest a way in which they can be automatically trimmed so they can't reach a certain size and thus fill up my partition?!

Thanks
Nunners