I just noticed that on one CentOS 5 server the logs messages, maillog and a couple of others have been blank for a couple of weeks!
I tracked down the error to /etc/sysconfig/rsyslogd
There was a line SYSLOGD_OPTIONS="-c3"
I googled that -c3 defines the "version" or "compatibility mode", and with 3 it means "rsyslog v3 native interface".
When I removed the option and restarted rsyslogd, the logging began to work again.
I wonder why is this. Probably this was caused by my recent system updates (yum update).
- Jussi