My host doesnt allow: shell_exec, exec, system or passthru - can i get around it?

public static function SafeExec($command) {
	static $AllowedExecFunctions = array();
	if (empty($AllowedExecFunctions)) {
		$AllowedExecFunctions = array('shell_exec'=>true, 'passthru'=>true, 'system'=>true, 'exec'=>true);
		foreach ($AllowedExecFunctions as $key => $value) {
			$AllowedExecFunctions[$key] = !phpthumb_functions::FunctionIsDisabled($key);
		}
	}
	$command .= ' 2>&1'; // force redirect stderr to stdout
	foreach ($AllowedExecFunctions as $execfunction => $is_allowed) {
		if (!$is_allowed) {
			continue;
		}
		$returnvalue = false;
		switch ($execfunction) {
			case 'passthru':
			case 'system':
				ob_start();
				$execfunction($command);
				$returnvalue = ob_get_contents();
				ob_end_clean();
				break;

			case 'exec':
				$output = array();
				$lastline = $execfunction($command, $output);
				$returnvalue = implode("\n", $output);
				break;

			case 'shell_exec':
				ob_start();
				$returnvalue = $execfunction($command);
				ob_end_clean();
				break;
		}
		return $returnvalue;
	}
	return false;
}