docker出现如下错误：Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

在docker中配置deepo时出现了错误：

在出现这个错误之前，我是先用如下命令查看NVIDIA-docker是否安装成功。

docker run --runtime=nvidia --rm nvidia/cuda nvidia-smi

出现如下显示：Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running

在网上查看原因，显示是nvidia-docker 没有注册，然后按照博客提示进行注册，通过下面的步骤：Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running

#To register the nvidia runtime, use the method below that is best suited to your environment.#You might need to merge t