TCL (Tool Command Language, typically pronounced as “tickle”) is a scripting language created by John Ousterhout in 1988 while working at the University of California, Berkeley. To provide additional functionality, TCL supports extensions. One of the most popular extensions is Expect which is a tool developed by Don Libes for automating and testing interactive applications such as ftp. telnet and ssh. I assume you know how to generate SSH keys using ssh-keygen and understand that if you want to be able to ssh to a remote system without entering a password you need to create the keys without a passphrase.