ruptime—shows the host status of local machines

ruptime [ –alrtu ]

ruptime gives a status line–like uptime for each machine on the local network; these are formed from packets broadcast by each host on the network once a minute. Machines for which no status report has been received for five minutes are shown as being down. Normally, the listing is sorted by hostname, but this order can be changed by specifying one of ruptime's options.