# File lib/multiruby.rb, line 274
  def self.root_dir
    root_dir = File.expand_path(ENV['MULTIRUBY'] ||
                                File.join(ENV['HOME'], ".multiruby"))

    unless test ?d, root_dir then
      puts "creating #{root_dir}"
      Dir.mkdir root_dir, 0700
    end

    root_dir
  end