static function execSystemCommand($cmd, &$return_code) {
	
		if (!function_exists('proc_open') || !function_exists('proc_close')) {
			throw new RuntimeException("Process execution functions are missing!");
		}
		
		$proc = proc_open($cmd, array(
			0 => array('pipe', 'r'),// stdin
			1 => array('pipe', 'w'),// stdout
			2 => array('pipe', 'w'),// stderr
		), $pipes);
	
		if ($proc===false) {
			throw new IOException("Error while calling proc_open");
		}
	
		$output = stream_get_contents($pipes[1]).' '.stream_get_contents($pipes[2]);
	
		$return_code = proc_close($proc);
	
		return $output;
	}