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* undefine Kernel#irb_original_require in without_rdoc method
* Don't rescue all LoadErrors/NameErrors in test_rendering.rb, just
the one for require 'yamatanooroti'

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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.



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


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):001:0> 1 + 2
=> 3
irb(main):002:1* class Foo
irb(main):003:2*   def foo
irb(main):004:2*     puts 1
irb(main):005:1*   end
irb(main):006:0> end
=> :foo
=> 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
    6: greet("World")

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


The following commands are available on IRB. You can get the same output from the show_cmds command.

  cwws           Show the current workspace.
  chws           Change the current workspace to an object.
  workspaces     Show workspaces.
  pushws         Push an object to the workspace stack.
  popws          Pop a workspace from the workspace stack.
  irb_load       Load a Ruby file.
  irb_require    Require a Ruby file.
  source         Loads a given file in the current session.
  irb            Start a child IRB.
  jobs           List of current sessions.
  fg             Switches to the session of the given number.
  kill           Kills the session with the given number.
  irb_info       Show information about IRB.
  show_cmds      List all available commands and their description.

  debug          Start the debugger of debug.gem.
  break          Start the debugger of debug.gem and run its `break` command.
  catch          Start the debugger of debug.gem and run its `catch` command.
  next           Start the debugger of debug.gem and run its `next` command.
  delete         Start the debugger of debug.gem and run its `delete` command.
  step           Start the debugger of debug.gem and run its `step` command.
  continue       Start the debugger of debug.gem and run its `continue` command.
  finish         Start the debugger of debug.gem and run its `finish` command.
  backtrace      Start the debugger of debug.gem and run its `backtrace` command.
  info           Start the debugger of debug.gem and run its `info` command.

  edit           Open a file with the editor command defined with `ENV["EDITOR"]`.
  measure        `measure` enables the mode to measure processing time. `measure :off` disables it.

  show_doc       Enter the mode to look up RI documents.
  ls             Show methods, constants, and variables. `-g [query]` or `-G [query]` allows you to filter out the output.
  show_source    Show the source code of a given method or constant.
  whereami       Show the source code around binding.irb again.


Environment Variables

  • NO_COLOR: Assigning a value to it disables IRB's colorization.
  • IRB_USE_AUTOCOMPLETE: Setting it to false disables IRB's autocompletion.
  • EDITOR: Its value would be used to open files by the edit command.
  • IRBRC: The file specified would be evaluated as IRB's rc-file.



After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at


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


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