FresherTechnicalDocker

Which Docker commands list containers, read logs and open a shell inside one?

Try answering first

Model answer

Three commands cover most day-to-day inspection.

docker ps                       # running containers
docker ps -a                    # all containers, including stopped ones
docker logs -f --tail 100 web   # follow the last 100 log lines
docker exec -it web sh          # open a shell inside a running container

docker ps lists running containers with their id, image, status and ports. Add -a to include stopped ones, which is how you find a container that crashed.
docker logs shows what the main process wrote to stdout and stderr. -f follows new lines, and --tail limits the output.
docker exec -it runs a new command in a running container. -i keeps stdin open and -t allocates a terminal. Use sh if the image has no bash.

Related: docker inspect web prints the full configuration, and docker stats shows live CPU and memory use.

exec works only on a running container. For a stopped one, read the logs, or start a new container from the same image with a shell as its entrypoint.

ps to find it, logs to see what happened, exec to look inside.

Key points

docker ps lists containers, and -a includes stopped ones
docker logs shows stdout and stderr, with -f to follow
docker exec -it opens a shell in a running container
exec needs a running container

Likely follow-ups

How do you get a shell in a container that keeps crashing?

Common mistakes

Looking only at docker ps and missing crashed containers
Trying bash in an image that only has sh