docker system prune -a

docker system prune -a
WARNING! This will remove:
        - all stopped containers
        - all networks not used by at least one container
        - all images without at least one container associated to them
        - all build cache
Are you sure you want to continue? [y/N] y

..../....

Total reclaimed space: 301MB

docker cp

See also

• docker system: docker system info , docker system events , docker system df, docker system prune -a

https://docs.docker.com/v17.12/edge/engine/reference/commandline/system_info/

https://docs.docker.com/v17.12/edge/engine/reference/commandline/system_events/