docker：无法连接到位于unix:///var/run/docker.sock的Docker守护进程。 docker 守护进程是否正在运行？

我通过 Visual Studio Code（VScode，版本 1.66）远程连接到学校服务器（Ubuntu 20.04.2 LTS）来执行一些任务，今天我关注 docker.com（https://docs.docker.com/engine/install/ubuntu/ https://docs.docker.com/engine/install/ubuntu/）在 Ubuntu 上安装 docker 引擎。

当我做sudo docker run hello-world通过运行以下命令来验证 Docker 引擎是否已正确安装hello-world完成所有步骤后，图像显示如下错误：

docker: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?.
See 'docker run --help'.

之后我检查docker version， 表明

Client: Docker Engine - Community
 Version: 20.10.14
 API version: 1.41
 Go version: go1.16.15
 Git commit: a224086
 Built: Thu Mar 24 01:48:02 2022
 OS/Arch: linux/amd64
 Context: default
 Experimental: true
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

然后看sudo docker info， 这表明

Client:
 Context: default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Docker Buildx (Docker Inc., v0.8.1-docker)
  scan: Docker Scan (Docker Inc., v0.17.0)

Server:
ERROR: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
errors pretty printing info

在我按照本教程卸载并重新安装docker后，它仍然显示这样的错误，我想我需要遵循docker的服务器端，但我不知道该怎么做？

这是历史：

root@yp:~# sudo apt-get remove docker docker-engine docker.io containerd runc
...
root@yp:~# sudo apt-get update
...
root@yp:~# sudo apt-get install \
>     ca-certificates \
>     curl \
>     gnupg \
>     lsb-release
...
root@yp:~# curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
...
root@yp:~# echo \
>   "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
>   $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
...
root@yp:~# sudo apt-get update
...
root@yp:~# sudo apt-get install docker-ce docker-ce-cli containerd.io
...
root@yp:~# sudo docker run hello-world
docker: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?.
See 'docker run --help'.

您应该首先在 systemctl 中启动并启用 docker

 systemctl start docker
 systemctl enable docker