Thanx guys, but it's not what i need.
I'm making a php script to ping a large wlan. That means every time the page loads it will ping about 200 routers. If six of those routers are offline i will have to wait 1 minute for the page to load with the default timeout. If one of the routers dont responde in 50ms I can assume there is something wrong, and it should time out.
shell_exec("ping -c1 -t0.05 10.0.0.51");
works fine on windows, but on linux the timeout is just to long.