What command was used on the host 192.168.123.5, to generate this output?

Running tcpdump -nli eth1 ‘icmp’ shows the following output:

11:56:35.599063 IP 192.168.123.5 > 194.25.2.129: icmp 64: echo request seq 1

11:56:35.670910 IP 194.25.2.129 > 192.168.123.5: icmp 64: echo reply seq 1

What command was used on the host 192.168.123.5, to generate this output?

Answer: ping