Automating interactive input

Automating interactive input for command-line utilities are extremely useful for writing automation tools or testing tools. There will be many situations when we deal with commands that read input interactively. An example of executing a command and supplying the interactive input is as follows:

$ command
Enter a number: 1
Enter name : hello
You have entered 1,hello

Getting ready

Creating utilities that can automate the acceptance of input are useful to supply input to local commands, as well as for remote applications. Let us see how to automate them.

How to do it...

Think about the sequence of an interactive input. From the previous code, we can formulate the steps of the sequence as follows:

1[Return]hello[Return]

Converting the preceding steps 1, Return, hello, and Return by observing the characters that are actually typed in the keyboard, we can formulate the following string:

"1\nhello\n"

The \n character is sent when we press return. By appending the return...