Ruby
Its easy to make GUIDs in Ruby. Modern Ruby (1.9+) has built-in UUID generation using the SecureRandom library, which is part of the standard library.
Modern Method (Recommended - Ruby 1.9+)
require 'securerandom'
uuid = SecureRandom.uuid
puts uuid # Example: "f47ac10b-58cc-4372-a567-0e02b2c3d479"
Alternative: Using the uuid Gem
If you need additional UUID generation options (version 1, 3, 5, etc.), use the modern uuid gem:
gem install uuid
require 'uuid'
uuid_generator = UUID.new
uuid = uuid_generator.generate
puts uuid
Legacy: uuidtools (Deprecated)
Note: The old uuidtools gem is deprecated and no longer maintained.
Use SecureRandom.uuid instead for modern Ruby applications.
# OLD - Do not use
# require 'uuidtools'
# UUIDTools::UUID.random_create