Check For Internet Connection From Script?

how can i check is internet connection available from a shell script?
i mean general check not hardware specific

tip: checkproc rcnetwork doesn't work out

thanks in advance

PS sorry for multiple posting :-) reply here, pls

You could ping a router somewhere at your ISP. Note that does not guarantee that you can reach any host, just that you are connected to your ISP. The router must also respond to pings. You can discover the routers in the path using traceroute.

if ping -c 3 some.router.at.isp.com
then
echo 'Have connectivity'
fi