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.