So, on your mac, you have docker installed. Ok. Then you say docker run --rm -it ubuntu /bin/bash, and voilá, ubuntu is downloaded and installed inside your docker, and since you said -it, which means "interactive", you have a bash prompt. Maybe you should use fish. Anyway, try >uname -a. We are not in Kansas anymore!

Here's the progress coming in. Uber, Lyft, whatever. They are just more efficient. And comfortable.