The rsh command (for remote shell) lets you execute a single command on a remote machine without having to log in formally. It can be a real time-saver when you know you only want to do one thing on the remote machine.
To execute a command on a remote machine, type:
rsh machinename command
$ rsh lonesome ls /home/lonesome/guitar collings gibson santacruz fender martin taylor $
For more information on the rsh(1) command and its options, refer to the man Pages(1): User Commands.