Returns a string representation for the exit code returned by the process.
This method relies on the Unix exit code status standardization and might not be relevant for other operating systems.
string A string representation for the exit status code
http://tldp.org/LDP/abs/html/exitcodes.html
http://en.wikipedia.org/wiki/Unix_signal
public function getExitCodeText() {
$this
->updateStatus();
return isset(self::$exitCodes[$this->exitcode]) ? self::$exitCodes[$this->exitcode] : 'Unknown error';
}