Cheat Sheet

Almost all commands work the same with podman instead of docker.

stateDiagram-v2
  [*] --> Created: create
  Created --> Running: start
  Running --> Paused: pause
  Paused --> Running: unpause
  Running --> Exited: stop
  Exited --> Running: start
  Exited --> [*]: rm

docker run is create and start in one step.

Running containers

Command	Effect
docker run -d --name web nginx	Starts a container in the background.
docker run -it --rm alpine sh	Interactive shell; the container is deleted on exit.
docker run -p 8080:80 nginx	Publishes container port 80 on host port 8080 (host:container).
docker run -v ./data:/data alpine	Mounts a host directory into the container.
docker run -v data:/data alpine	Mounts the named volume data (created if missing).
docker run -e KEY=value alpine	Sets an environment variable.
docker run --restart unless-stopped nginx	Restarts the container after crashes and reboots.
docker exec -it web sh	Opens a shell in a running container.
docker attach web	Attaches to the main process; Ctrl+P Ctrl+Q detaches without stopping it.
docker stop web / docker start web	Stops (SIGTERM, then SIGKILL after 10 s) or starts it again.
docker pause web / docker unpause web	Freezes and resumes all processes.

Tip

Containers reach each other by name only on a user-defined network: docker network create app, then docker run --network app --name db …. Other containers on app can connect to db. The old --link option is deprecated.

Inspecting

Command	Shows
docker ps / docker ps -a	Running containers / all containers.
docker logs -f --tail 100 web	The last 100 log lines, then follows new output.
docker inspect web	Full configuration and state as JSON.
docker stats	Live CPU, memory and network usage.
docker diff web	Files changed in the container compared to its image.
docker info	Engine configuration, storage driver and resource counts.

Images

Command	Effect
docker pull nginx:1.27	Downloads an image. Without a tag, latest is used.
docker build -t myapp:1.0 .	Builds an image from the Containerfile or Dockerfile in ..
docker images	Lists local images.
docker history myapp:1.0	The layers of an image and their sizes.
docker commit web myimage	Saves a container’s current state as a new image.

Cleaning up

Command	Removes
docker system df	Nothing; shows how much space can be reclaimed.
docker container prune	All stopped containers.
docker image prune -a	All images not used by a container.
docker volume prune -a	All volumes not used by a container, including their data.
docker system prune -a	Stopped containers, unused networks and images, and the build cache.
docker rm -f $(docker ps -aq)	Every container, including running ones.