luasocket/samples/echoclnt.lua

host = host or "localhost"
port = port or 7
if arg then
    host = arg[1] or host
    port = arg[2] or port
end
host = toip(host)
udp, err = udpsocket()
if not udp then print(err) exit() end
err = udp:setpeername(host, port)
if err then print(err) exit() end
print("Using host '" ..host.. "' and port " .. port .. "...")
while 1 do
	line = read()
	if not line then exit() end
	err = udp:send(line)
	if err then print(err) exit() end
	dgram, err = udp:receive()
	if not dgram then print(err) exit() end
	print(dgram)
end