rusers —
who is logged in to machines on local network
The rusers command produces output similar to
  who(1), but for the list of hosts
  or all machines on the local network. For each host responding to the rusers
  query, the hostname with the names of the users currently logged on is printed
  on each line. The rusers command will wait for one minute to catch late
  responders.
The following options are available:
  - -a
- Print all machines responding even if no one is currently logged in.
- -l
- Print a long format listing. This includes the user name, host name, tty
      that the user is logged in to, the date and time the user logged in, the
      idle time (in minutes), and the remote host they logged in from (if
      applicable).
  - rusers: RPC: Program not registered
- The rpc.rusersd(8)
      daemon has not been started on the remote host.
- rusers: RPC: Timed out
- A communication error occurred. Either the network is excessively
      congested, or the
      rpc.rusersd(8) daemon
      has terminated on the remote host.
- rusers: RPC: Port mapper failure - RPC: Timed out
- The remote host is not running the portmapper (see
      rpcbind(8)), and cannot
      accommodate any RPC-based services. The host may be down.
Therusers command appeared in SunOS.
The sorting options are not implemented.