Ruby: Running Code & Tools

Running Ruby

ruby script.rb            # run a script
irb                       # interactive Ruby (REPL)
ruby -e "puts 1 + 1"     # run inline code

irb (Interactive Ruby) is your REPL — great for experimenting with expressions and testing syntax.

Editors / IDEs

• VS Code — install the Ruby extension by rebornix (Ruby language support, debugger, linting)
• RubyMine — JetBrains IDE for Ruby (paid, but full-featured with Rails support)
• Vim/Neovim with ruby-lsp for LSP-based autocompletion and diagnostics

Gems (package manager)

Ruby libraries are called gems, distributed via rubygems.org. The gem command manages them:

gem install rails         # install a gem
gem list                 # list installed gems
gem env                  # show gem environment

Bundler (dependency manager)

Production projects use Bundler to manage gem versions:

gem install bundler       # install Bundler
bundle init               # create Gemfile
bundle install            # install from Gemfile
bundle exec ruby app.rb   # run with locked gems

Ruby on Rails

Ruby's most famous framework:

gem install rails
rails new my_app          # generate a full Rails app
rails server              # start dev server
rails generate model User name:string email:string
rails db:migrate

Testing

Ruby has a strong testing culture:

# test/example_test.rb
require 'minitest/autorun'

class MathTest < Minitest::Test
  def test_addition
    assert_equal 5, 2 + 3
  end
end

Run tests: ruby test/example_test.rb or rails test in a Rails project.

Popular alternative frameworks

Quick check below!