Expect is one way to automate your scripts by expecting what the output may be. For example you want to create a script that helps you to login to a telnet session and enter your login and password for you. Here is the simple example which helps you to do it. Above example will login to your router and enter your username and password and list all the possible commands using ? and then let you to interact with using interact command. You can automate anything for example applications, ssh etc..