If you have php.ini setup to send PHP errors to syslog, they will all get dumped into /var/log/messages (at least it does with RedHat 9 by default). I wanted to figure out how to get PHP errors to go to their own syslog file.
After some trial and error, I figured out what facility and priority PHP uses, which is "user.notice". So, to get your PHP errors going to a separate syslog file, put this line in your /etc/syslog.conf :
Then restart syslogd:
Why PHP uses "user" as the facility I'm not sure, probably because it's the only one that works under Windows?