Changing behavior when starting a container

Let's see how the ENV Dockerfile instruction works in practice. We've added a Dockerfile to your current working directory with the following instructions:

FROM ubuntu:22.04
ENV NAME=Tim
CMD echo "Hello, my name is $NAME"

The Dockerfile will print a personalized message, Hello, my name is Tim, on startup. Let's see how we can change this personalized message even after building an image from the Dockerfile.