$ gem install ruby_version

require 'ruby_version'

# Output RUBY_VERSION
RubyVersion.to_s
# Check for the main version with a Float
RubyVersion.is? 2.1
# Use strings for exacter checking
RubyVersion.is.above '1.9.2'
RubyVersion.is.at_least '2.0.0' # or exactly, below, at_most
# You can use the common comparison operators
RubyVersion >= '1.8.7'
RubyVersion.between? '1.8.7', '1.9.2'
# Relase date checks
RubyVersion.is.older_than Date.today
RubyVersion.is.newer_than '2009-08-19'
# Misc Accessors
RubyVersion.major # => 1
RubyVersion.minor # => 8
RubyVersion.tiny  # => 7
RubyVersion.patchlevel # => 249
RubyVersion.description # => "ruby 1.8.7 (2010-01-10 patchlevel 249) [i486-linux]"