Interactive Ruby shell

One other tool that’s worth mentioning and that comes with Ruby runtime is IRB. We can start it by typing irb in the shell and hitting “Enter.”

Its name is short for Interactive Ruby Shell, and yes, it’s another kind of shell. Just like the shell running in the terminal, irb is also a program that interactively waits for us to type something and hit “Enter.” However, because this is a Ruby shell, it expects that we type Ruby code instead of system commands.

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