Mastering Chef

IRB

IRB is an acronym for "interactive Ruby". It's a tool that provided alongside Ruby interpreter, which allows for the interactive execution of Ruby expressions. These expressions are delivered to IRB using standard input.

Let's quickly see IRB in action:

  ~  irb
2.1-head :001 >

When we enter the irb command, it throws a shell at us. The format of the shell prompt is as follows:

$RUBY_VERSION :$LINE_NUMBER >

You can customize this prompt to your liking. However, for now, just remember that whatever expression you enter at the prompt is interpreted as a Ruby expression and is evaluated right away.

Consider the following as an example:

irb
2.1-head :001 > 2+3
 => 5

As you can see, we entered an arithmetic expression to compute the sum of two numbers, ...