我正在尝试安装 Nvidia 驱动程序，直到出现此错误：
ERROR: You appear to be running an X server; please exit X before
installing. For further details, please see the section INSTALLING
THE NVIDIA DRIVER in the README available on the Linux driver
download page at www.nvidia.com.
ERROR: Installation has failed. Please see the file
'/var/log/nvidia-installer.log' for details. You may find
suggestions on fixing installation problems in the README available
on the Linux driver download page at www.nvidia.com.
然后我尝试了他的方法：
sudo killall Xorg
我得到了：
Xorg: no process found
但是尝试安装 Nvidia 时仍然出现同样的错误，我该怎么办？