how to build docker image
docker build <Dockerfile path> -t image-name
how to start docker
systemctl start docker.service
#(OR)
systemctl start docker
# it will start docker
start a docker container
$ docker start <container_id>
docker run image
docker run <image id> --name 'container name'
start docker image
docker start centos
docker how to run existing container
docker start <container-name/ID>