module Thor::Util

def self.ruby_command
  @ruby_command ||= begin
    ruby_name = RbConfig::CONFIG['ruby_install_name']
    ruby = File.join(RbConfig::CONFIG['bindir'], ruby_name)
    ruby << RbConfig::CONFIG['EXEEXT']
    # avoid using different name than ruby (on platforms supporting links)
    if ruby_name != 'ruby' && File.respond_to?(:readlink)
      begin
        alternate_ruby = File.join(RbConfig::CONFIG['bindir'], 'ruby')
        alternate_ruby << RbConfig::CONFIG['EXEEXT']
        # ruby is a symlink
        if File.symlink? alternate_ruby
          linked_ruby = File.readlink alternate_ruby
          # symlink points to 'ruby_install_name'
          ruby = alternate_ruby if linked_ruby == ruby_name || linked_ruby == ruby
        end
      rescue NotImplementedError
        # just ignore on windows
      end
    end
    # escape string in case path to ruby executable contain spaces.
    ruby.sub!(/.*\s.*/m, '"\&"')
    ruby
  end
end