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.
[!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
[!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.
irb ExecutableYou 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
binding.irb BreakpointIf 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
The following commands are available on IRB. You can get the same output from the help command.
Help
help List all available commands. Use `help <command>` to get information about a specific command.
IRB
context Displays current configuration.
exit Exit the current irb session.
exit! Exit the current process.
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.
history Shows the input history. `-g [query]` or `-G [query]` allows you to filter the output.
disable_irb Disable binding.irb.
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.
cd Move into the given object or leave the current context.
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 or source location.
measure `measure` enables the mode to measure processing time. `measure :off` disables it.
Context
show_doc Look up documentation with RI.
ls Show methods, constants, and variables.
show_source Show the source code of a given method, class/module, or constant.
whereami Show the source code around binding.irb again.
Helper methods
conf Returns the current IRB context.
Aliases
$ Alias for `show_source`
@ Alias for `whereami`
Starting from version 1.8.0, IRB boasts a powerful integration with debug.gem, providing a debugging experience akin to pry-byebug.
After hitting a binding.irb breakpoint, you can activate the debugger with the debug command. Alternatively, if the debug method happens to already be defined in the current scope, you can call irb_debug.
From: test.rb @ line 3 :
1:
2: def greet(word)
=> 3: binding.irb
4: puts "Hello #{word}"
5: end
6:
7: greet("World")
irb(main):001> debug
irb:rdbg(main):002>
Once activated, the prompt's header changes from irb to irb:rdbg, enabling you to use any of debug.gem's commands:
irb:rdbg(main):002> info # use info command to see available variables
%self = main
_ = nil
word = "World"
irb:rdbg(main):003> next # use next command to move to the next line
[1, 7] in test.rb
1|
2| def greet(word)
3| binding.irb
=> 4| puts "Hello #{word}"
5| end
6|
7| greet("World")
=>#0 Object#greet(word="World") at test.rb:4
#1 <main> at test.rb:7
irb:rdbg(main):004>
Simultaneously, you maintain access to IRB's commands, such as show_source:
irb:rdbg(main):004> show_source greet
From: test.rb:2
def greet(word)
binding.irb
puts "Hello #{word}"
end
debug.gemdebug.gem offers many advanced debugging features that simple REPLs can't provide, including:
To learn about these features, please refer to debug.gem's commands list.
In the irb:rdbg session, the help command will also display all commands from debug.gem.
debug.gem's ConsoleThis integration offers several benefits over debug.gem's native console:
show_source or show_doc.@ (whereami) and $ (show_source).However, there are also some limitations to be aware of:
binding.irb doesn't support pre and do arguments like binding.break.debug.gem's remote debugging feature._ is not supported.IRB's default completion IRB::RegexpCompletor uses Regexp. IRB has another experimental completion IRB::TypeCompletor that uses type analysis.
Install ruby/repl_type_completor with:
$ gem install repl_type_completor
Or add these lines to your project's Gemfile.
gem 'irb'
gem 'repl_type_completor', group: [:development, :test]
Now you can use type based completion by:
Running IRB with the --type-completor option
$ irb --type-completor
Or writing this line to IRB's rc-file (e.g. ~/.irbrc)
IRB.conf[:COMPLETOR] = :type # default is :regexp
Or setting the environment variable IRB_COMPLETOR
ENV['IRB_COMPLETOR'] = 'type'
IRB.start
To check if it's enabled, type irb_info into IRB and see the Completion section.
irb(main):001> irb_info
...
# Enabled
Completion: Autocomplete, ReplTypeCompletor: 0.1.0, Prism: 0.18.0, RBS: 3.3.0
# Not enabled
Completion: Autocomplete, RegexpCompletor
...
If you have sig/ directory or rbs_collection.lock.yaml in current directory, IRB will load it.
IRB::TypeCompletor can autocomplete chained methods, block parameters and more if type information is available. These are some examples IRB::RegexpCompletor cannot complete.
irb(main):001> 'Ruby'.upcase.chars.s # Array methods (sample, select, shift, size)
irb(main):001> 10.times.map(&:to_s).each do |s|
irb(main):002> s.up # String methods (upcase, upcase!, upto)
irb(main):001> class User < ApplicationRecord
irb(main):002> def foo
irb(main):003> sa # save, save!
As a trade-off, completion calculation takes more time than IRB::RegexpCompletor.
Compared with Steep, IRB::TypeCompletor has some difference and limitations.
[0, 'a'].sample.
# Steep completes intersection of Integer methods and String methods
# IRB::TypeCompletor completes both Integer and String methods
Some features like type narrowing is not implemented.
def f(arg = [0, 'a'].sample)
if arg.is_a?(String)
arg. # Completes both Integer and String methods
Unlike other static type checker, IRB::TypeCompletor uses runtime information to provide better completion.
irb(main):001> a = [1]
=> [1]
irb(main):002> a.first. # Completes Integer methods
NO_COLOR: Assigning a value to it disables IRB's colorization.IRB_USE_AUTOCOMPLETE: Setting it to false disables IRB's autocompletion.IRB_COMPLETOR: Configures IRB's auto-completion behavior, allowing settings for either regexp or type.VISUAL: Its value would be used to open files by the edit command.EDITOR: Its value would be used to open files by the edit command if VISUAL is unset.IRBRC: The file specified would be evaluated as IRB's rc-file.IRB v1.13.0 and later versions allows users/libraries to extend its functionality through official APIs.
For more information, please visit EXTEND_IRB.md.
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.
Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/irb.
git clone git@github.com:[your_username]/irb.gitbundle installbundle exec rake to make sure tests pass locallyIf your changes affect component rendering, such as the autocompletion's dialog/dropdown, you may need to run IRB's integration tests, known as yamatanooroti.
Before running these tests, ensure that you have libvterm installed. If you're using Homebrew, you can install it by running:
brew install libvterm
After installing libvterm, you can run the integration tests using the following commands:
WITH_VTERM=1 bundle install
WITH_VTERM=1 bundle exec rake test test_yamatanooroti
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.
FAQs
Unknown package
We found that irb demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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