Thankfully pinging from an Ubuntu server is very similar to how its done on Windows systems.
To ping a website or ip address 4 times use
ping -c 4 hostname
to do 8 requests
ping -c 8 hostname
-c parameter the ping requests will keep running until you manually cancel it. The
-c stands for count and stops the ping after that amount of packets have been sent.
You can read more up on ping at the Ubuntu manual.