docker ps
docker ps [-a] [-q] [--filter key=value]
Risk: Safe
What it does
Lists running containers.
When to use it
To see what is running and its state.
Example
$ docker ps -aShow all containers, stopped ones too.
$ docker ps -qOnly the ids.
$ docker ps --filter status=exitedOnly stopped containers.
Learn it in: Container states: ps -a and inspect · Official docs