9 Essential Docker Commands for Live Operations

1. View running containers

List currently running containers: docker ps Include stopped containers with the -a flag: docker ps -a Typical output:

CONTAINER ID   IMAGE   STATUS
a12b34cd   nginx   Up 3 days
b23c45de67   redis   Up 5 days

2. View container logs

Show logs for a specific container (e.g., nginx): docker logs nginx Common options: -f – follow logs in real time. --tail 100 – display the last 100 lines. --since 10m – show logs from the last 10 minutes.

3. Enter a container

Open an interactive shell inside a container: docker exec -it nginx bash If the image does not contain bash, fall back to sh: docker exec -it nginx sh Typical tasks inside the container include inspecting configuration files, checking processes, or testing network connectivity.

4. View container resource usage

Show live CPU, memory, and I/O statistics for all containers: docker stats Monitor a single container by specifying its name: docker stats nginx Sample output:

CONTAINER   CPU %   MEM USAGE
nginx       2.1%    120MB
redis       0.5%    80MB

5. Inspect container details

Retrieve the full JSON description of a container: docker inspect nginx Common queries:

IP address: docker inspect nginx | grep IPAddress Mounted directories: inspect the Mounts field in the JSON output.

6. Restart containers

Restart one or multiple containers:

docker restart nginx
docker restart nginx redis mysql

7. Stop and start containers

Gracefully stop a container: docker stop nginx Start it again: docker start nginx Force termination when a container does not stop cleanly:

docker kill nginx

8. Manage images

List all images on the host: docker images Typical output shows repository, tag, and size:

REPOSITORY   TAG      SIZE
nginx        latest   133MB
redis        7        98MB
mysql        8.0      447MB

Delete an unused image by its ID:

docker rmi <image-id>

9. Clean up unused resources

Check disk usage of Docker objects: docker system df Remove all stopped containers, unused networks, dangling images, and build cache: docker system prune Force removal without confirmation (including unused images): docker system prune -a Remove unused volumes:

docker volume prune

Operational cheat sheet

When a service is down:

docker ps
docker logs <container>

When CPU spikes:

docker stats
docker exec -it <container> top

When network issues appear:

docker inspect <container>
docker exec -it <container> ping …

When configuration problems arise, open a shell and inspect files (e.g., /etc/nginx/nginx.conf).

When disk space is exhausted:

docker system df
docker system prune