Let's do another small experiment. If you have left it again, let's get back to the ubu container by running docker container start -i ubu and then let's create a file. Nothing major, just a file called welomce.txt with the content "hello" in it. (You can use the echo command with redirection to accomplish this.

Then type in exit to leave the container and to let it stop. You alread know how to list all the containers so you can verify it still exists but it does not run any more.

# echo hello > welcome.txt
# exit