def chmod_R(mode, list, options = {})
    fu_check_options options, OPT_TABLE['chmod_R']
    list = fu_list(list)
    fu_output_message sprintf('chmod -R%s %o %s',
                              (options[:force] ? 'f' : ''),
                              mode, list.join(' ')) if options[:verbose]
    return if options[:noop]
    list.each do |root|
      Entry_.new(root).traverse do |ent|
        begin
          ent.chmod(fu_mode(mode, ent.path))
        rescue
          raise unless options[:force]
        end
      end
    end
  end
Options: noop verbose force

Changes permission bits on the named files (in +list+)
to the bit pattern represented by +mode+.

FileUtils.chmod_R 0700, "/tmp/app.#{$$}"
FileUtils.chmod_R "u=wrx", "/tmp/app.#{$$}"