def ls(mask = '', raise = true)
      ls_items = []
      mask = '"' + mask + '"' if mask.include? ' '
      output = exec 'ls ' + mask
      output.lines.each do |line|
        ls_item = LsItem.from_line(line)
        ls_items << ls_item if ls_item
      end
      ls_items
    rescue Client::RuntimeError => e
      raise e if raise
      []
    end
def ls(mask = '', raise = true)
      ls_items = []
      mask = '"' + mask + '"' if mask.include? ' '
      output = exec 'ls ' + mask
      output.lines.each do |line|
        ls_item = LsItem.from_line(line)
        ls_items << ls_item if ls_item
      end
      ls_items
    rescue Client::RuntimeError => e
      raise e if raise
      []
    end
List contents of a remote directory
 @param [String] mask The matching mask
 @param [Boolean] raise If set, an error will be raised. If set to
 +false+, an empty array will be returned
 @return [Array] List of +mask+ matching LsItems