`IRB`

IRB stands for "interactive Ruby" and is a tool to interactively execute Ruby expressions read from the standard input.

The irb command from your shell will start the interpreter.

Installation

[!Note]

IRB is a default gem of Ruby so you shouldn't need to install it separately.

But if you're using Ruby 2.6 or later and want to upgrade/install a specific version of IRB, please follow these steps.

To install it with bundler, add this line to your application's Gemfile:

gem 'irb'

And then execute:

$ bundle

Or install it directly with:

$ gem install irb

Usage

[!Note]

We're working hard to match Pry's variety of powerful features in IRB, and you can track our progress or find contribution ideas in this document.

The `irb` Executable

You can start a fresh IRB session by typing irb in your terminal.

In the session, you can evaluate Ruby expressions or even prototype a small Ruby script. An input is executed when it is syntactically complete.

$ irb
irb(main):001> 1 + 2
=> 3
irb(main):002* class Foo
irb(main):003*   def foo
irb(main):004*     puts 1
irb(main):005*   end
irb(main):006> end
=> :foo
irb(main):007> Foo.new.foo
1
=> nil

The `binding.irb` Breakpoint

If you use Ruby 2.5 or later versions, you can also use binding.irb in your program as breakpoints.

Once a binding.irb is evaluated, a new IRB session will be started with the surrounding context:

$ ruby test.rb

From: test.rb @ line 2 :

    1: def greet(word)
 => 2:   binding.irb
    3:   puts "Hello #{word}"
    4: end
    5:
    6: greet("World")

irb(main):001:0> word
=> "World"
irb(main):002:0> exit
Hello World

Debugging

You can use IRB as a debugging console with debug.gem with these options:

In binding.irb, use the debug command to start an irb:rdbg session with access to all debug.gem commands.
Use the RUBY_DEBUG_IRB_CONSOLE=1 environment variable to make debug.gem use IRB as the debugging console.

To learn more about debugging with IRB, see Debugging with IRB.

Documentation

https://ruby.github.io/irb/ provides a comprehensive guide to IRB's features and usage.

Configuration

See the Configuration page in the documentation.

Extending IRB

IRB v1.13.0 and later versions allows users/libraries to extend its functionality through official APIs.

For more information, please visit the IRB Extension Guide.

Contributing

See CONTRIBUTING.md for more information.

Releasing

rake release
gh release create vX.Y.Z --generate-notes

License

The gem is available as open source under the terms of the 2-Clause BSD License.

IRB