ip a
で
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host lovalid_lft forever preferred_lft foreverinet6 ::1/128 scope hostvalid_lft forever preferred_lft forever2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 qdisc mq state UP group default qlen 1000link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ffinet 172.31.8.10/20 brd 172.31.15.255 scope global dynamic eth0valid_lft 2442sec preferred_lft 2442sec
のeth0とかens18みたいな名前で2つ目が出てくるかどうか