Befehle

Löscht alle gestoppten Container
Windows -> docker container prune

Linux

One liner to stop / remove all of Docker containers:

docker stop $(docker ps -a -q)

docker rm $(docker ps -a -q)

docker save -o <path for generated tar file> <image name>
Then copy your image to a new system with regular file transfer tools such as cp, scp or rsync(preferred for big files). After that you will have to load the image into Docker:

docker load -i <path to image tar file>
PS: You may need to sudo all commands.