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
- Usage
- Commands
- Debugging with IRB
- Type Based Completion
- Configuration
- Documentation
- Extending IRB
- Development
- Contributing
- Releasing
- License
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 irbNote
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.
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
=> nilIf 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 WorldThe 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
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.
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.
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 Enter the mode to look up RI documents.
ls Show methods, constants, and variables.
show_source Show the source code of a given method or constant.
whereami Show the source code around binding.irb again.
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}"
enddebug.gem offers many advanced debugging features that simple REPLs can't provide, including:
- Step-debugging
- Frame navigation
- Setting breakpoints with commands
- Thread control
- ...and many more
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.
This integration offers several benefits over debug.gem's native console:
- Access to handy IRB commands like
show_sourceorshow_doc. - Support for multi-line input.
- Symbol shortcuts such as
@(whereami) and$(show_source). - Autocompletion.
- Customizable prompt.
However, there are also some limitations to be aware of:
binding.irbdoesn't supportpreanddoarguments likebinding.break.- As IRB doesn't currently support remote-connection, it can't be used with
debug.gem's remote debugging feature. - Access to the previous return value via the underscore
_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 :regexpOr setting the environment variable IRB_COMPLETOR
ENV['IRB_COMPLETOR'] = 'type'
IRB.startTo 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 methodsSome features like type narrowing is not implemented.
def f(arg = [0, 'a'].sample)
if arg.is_a?(String)
arg. # Completes both Integer and String methodsUnlike 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 methodsNO_COLOR: Assigning a value to it disables IRB's colorization.IRB_USE_AUTOCOMPLETE: Setting it tofalsedisables IRB's autocompletion.IRB_COMPLETOR: Configures IRB's auto-completion behavior, allowing settings for eitherregexportype.VISUAL: Its value would be used to open files by theeditcommand.EDITOR: Its value would be used to open files by theeditcommand ifVISUALis 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.
- Fork the project to your GithHub account
- Clone the fork with
git clone [email protected]:[your_username]/irb.git - Run
bundle install - Run
bundle exec raketo make sure tests pass locally
If 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 libvtermAfter 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_yamatanoorotirake 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.
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