Docker - Command (CMD)

About

cmd defines a command that should be run inside the container.

You can explicitly pass the cmd as argument to the docker cli.

docker run cmd # start a container and run a cmd
docker exec cmd # run a cmd against a running container

Example:

docker run -i -t ubuntu bash

the image is ubuntu
the entrypoint is the default /bin/sh -c because there is no ENTRYPOINT in the ubuntu dockerfile
and the command is bash.

You can add a cmd ¹⁾ in a dockerfile

The command line arguments to docker run will be appended after all elements in an exec form ENTRYPOINT
Otherwise the CMD parameter of a dockerfile

docker inspect --format "{{range .Config.Cmd}}{{.}}{{end}}" containerOrImageName

¹⁾