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:
$ bundleOr install it directly with:
$ gem install irbUsage
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
irb(main):007:0> Foo.new.foo
1
=> nilThe 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 WorldCommands
The following commands are available on IRB. You can get the same output from the show_cmds command.
Workspace
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
irb_load Load a Ruby file.
irb_require Require a Ruby file.
source Loads a given file in the current session.
irb_info Show information about IRB.
show_cmds List all available commands and their description.
Multi-irb (DEPRECATED)
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.
Debugging
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.
Misc
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.
Context
help [DEPRECATED] Enter the mode to look up RI documents.
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.
Configuration
Environment Variables
NO_COLOR: Assigning a value to it disables IRB's colorization.IRB_USE_AUTOCOMPLETE: Setting it tofalsedisables IRB's autocompletion.EDITOR: Its value would be used to open files by theeditcommand.IRBRC: The file specified would be evaluated as IRB's rc-file.
Documentation
https://docs.ruby-lang.org/en/master/IRB.html
Development
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 rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/irb.
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.