[syslog-ng] filtering based on text?

Hey folks, I've looked for a way to do this, and I guess my google-foo is weak today. I've got a situation where on one of my machines, an automated process FREQUENTLY calls sudo so it can gain the permissions it needs to do certain tasks. But that means my /var/log/messages is getting FILLED with sudo messages. I was hoping I could insert some kind of text filter that would allow me to shunt messages where one user (the automated process) calls sudo into another log file. It would basically need to be a nested filter, i.e.: If message_source = sudo then     if user = X then         log to auto_sudo.log If someone knows how this can be done, I'd appreciate it. Thanks! --- Dan