rsh, ssh, rcp, scp

The following commands are based on RPC (Remote Procedure calls).
They allow to copy files, execute a command or
open a terminal session on the remote host.

rsh (remote shell):
Utility for executing a command on a remote machine.

rsh [-l username] remote_machine [command]

For security reasons, ssh is the preferable service for logging in remotely.

ssh (secure shell):

ssh [-l ] remote_machine

rcp (remote copy), scp (secure copy):
These two commands copy files from one machine
to another using a similar notation to cp.
scp is the secure version from the ssh package.

rcp [-r] [uesr@host1:]file1 [user@host2:]file2

scp [-r] [[user@]host1:]file1 [...] [[user@]host2:]file2
 
 Options:

  Copy recursively: -r