比如ping 4.2.2.2
PING 4.2.2.2 (4.2.2.2) 56(84) bytes of data.
64 bytes from 4.2.2.2: icmp_req=1 ttl=56 time=18.7 ms
64 bytes from 4.2.2.2: icmp_req=2 ttl=56 time=19.3 ms
64 bytes from 4.2.2.2: icmp_req=3 ttl=56 time=18.3 ms
64 bytes from 4.2.2.2: icmp_req=4 ttl=56 time=17.9 ms