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When writing a bash script that starts a docker container, it is useful to refer to the started docker container. How do you get the specific container id of a docker container when you start it?

P.S. I know that I can use --name to name the container, which I can use to filter the list of containers using docker ps -aqf "name=containername", but this will fail if I ever start the script twice. And then there's the possibility of name conflicts. Besides, what's the point of container IDs if you can't use them?

Answers

When you start a detached container, it returns the container ID. e.g.:

$ docker run -d ubuntu:18.04
71329cf6a02d89cf5f211072dd37716fe212787315ce4503eaee722da6ddf18f

In bash, you can define a new variable from the output like this:

CID=$(docker run -d ubuntu:18.04)

Then, later you can use this variable to refer to your container like this:

docker stop $CID
docker rm $CID