docker interactive shell
docker exec -it [containerid/name] [shell]
#Example
docker exec -it fa80b69 bash
#if its an apline container use "sh" instead of "bash"
docker start container
$ docker start my_container
docker run command on container
sudo docker exec -it <container name> <command>
docker attach
docker attach [OPTIONS] CONTAINER
docker how to run existing container
docker start <container-name/ID>