Print list of active users on a host
who@ [ host ]
who@ connects to TCP port 11 (Systat) on host and prints any data it receives. It removes CR and converts unprintable characters to a visible format.
If host is not supplied, who@ connects to the local host.
Some computers respond to port 11 with a list of active users. For example, they may be running
tcpserver 0 11 who &