Docker container --rm option to clean up and remove containers from process list.

docker container run --rm -it --name mycentos centos:7 bash
docker container run --rm -it --name myubun ubuntu:14.04 bash


After exiting each container - the '--rm' option automatically removes the container from the
process list.

I.E you will not see these containers when you do a  'docker container ps -a' command.