docker
ubuntu 18.04
https://www.digitalocean.com/community/tutorials/how-to-install-and-use-docker-on-ubuntu-18-04
`docker ps -aq
docker stop $(docker ps -aq)
docker rm $(docker ps -a -q)
docker images "dangling=true" -q
docker rmi -f $(docker images -f "dangling=true" -q)