String cmd = String.format("echo %s > %s\n", arg, mSwitchUsbFileTextEdit.getText().toString());
try {
Process exeEcho = Runtime.getRuntime().exec("su");
exeEcho.getOutputStream().write(cmd.getBytes());
exeEcho.getOutputStream().flush();
} catch (IOException e) {
showMessage("Excute exception: " + e.getMessage());
}