Let's check with "reveal codes": $ ping -a 127.0.0.1 | less PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data. 64 bytes from 127.0.0.1: icmp_seq=1

Let's check with "reveal codes": $ ping -a 127.0.0.1 | less PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data. 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.029 ms^G 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.023 ms^G Looks like you need a terminal that has a BEL sound.