who is logged in on local machines
rwho [-a]
The rwho utility produces output similar to who, but for all machines on the local network. If no report has been received from a machine for five minutes, rwho assumes the machine is down, and doesn't report users last known to be logged into that machine.
If a user hasn't typed to the system for a minute or more, rwho reports this idle time. If a user hasn't typed to the system for an hour or more, that user will be omitted from the output of rwho unless the -a option is given.
This utility is unwieldy when the number of machines on the local net is large.