class SystemUniversal

def self.ruby
  return @ruby if @ruby
  c = begin; ::RbConfig::CONFIG; rescue NameError; ::Config::CONFIG; end
  ruby = File.join(c['bindir'], c['ruby_install_name']) << c['EXEEXT']
  @ruby = if system('%s -e 42' % ruby)
    ruby
  else
    system('%s -e 42' % 'ruby') ? 'ruby' : warn('no ruby in PATH/CONFIG')
  end
end