docker installation
It is best to use Docker through a non-root user. At this time, you need to add a non-root user to the local Docker Unix group.
Use the wgetDocker installation script obtained from https://get.docker.com and run it, and then use the pipeline ( pipe) in the Shell to execute the script
$ wget -qO- https://get.docker.com/ | sh
The following command shows how to add a user named clf to the Docker group and how to confirm whether the operation was executed successfully.
$ sudo usermod -aG docker clf
$ cat /etc/group | grep docker
docker:x:999:clf