how to make a PHP process auto-restart when dead?

Question

Something like a daemon that will never die,

my system is fedora10

Answer 1

while true; do php daemon.php; done

If small outages are acceptable, add sleep 1; before done so that a continually failing daemon's spawn rate is somewhat limited.

Answer 2

Do you want to know how to construct such a service or just how to restart it in case of failure?

You could use something on system-level, like "monit": http://www.cyberciti.biz/tips/howto-monitor-and-restart-linux-unix-service.html