This program is used to send multiple system commands to a group of UNIX-like
remote servers simultaneously using concurrent processes. Supported protocols:
FTP, SFTP, TELNET, SSH and SCP. With telnet and ssh all system command are
supported provided that they are not interactive.

Its main usage is to send repetitive sysadmin tasks to a group of servers but
you can also use it for automatic ftp or scp backup and much more.

Commands are exactly those you type on your terminal. It also allow you to use
'su -' to execute your commands under the TELNET and SSH protocols.