code: public function setSetserialFlag($param, $arg = "")
      {
          if (!$this->_ckOpened()) {
              return false;
          }
  
          $return = exec(
              "setserial " . $this->_device . " " . $param . " " . $arg . " 2>&1"
          );
  
          if ($return{0} === "I") {
              trigger_error("setserial: Invalid flag", E_USER_WARNING);
  
              return false;
          } elseif ($return{0} === "/") {
              trigger_error("setserial: Error with device file", E_USER_WARNING);
  
              return false;
          } else {
              return true;
          }
      }
docs: Sets a setserial parameter (cf man setserial)
  NO MORE USEFUL !
  -> No longer supported
  -> Only use it if you need it
  
  @param  string $param parameter name
  @param  string $arg   parameter value
  @return bool