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Docker Basics – Command Reference
Docker Installation and Health Checks
docker version
Purpose
Verifies that the Docker CLI is installed and whether it can communicate with the Docker daemon.
What it shows
Client version information and server (daemon) version information.
Usage
docker version
Notes
If the Docker daemon is not running, only client information is shown and the server section fails.
docker info
Purpose
Displays detailed system-wide Docker configuration and runtime information.
What it shows
Docker root directory, storage driver, number of images and containers, OS and architecture details.
Usage
docker info
Working With Containers
docker run
Purpose
Creates and starts a new container from an image.
Common usage
docker run hello-world
docker run -it ubuntu bash
docker run -d –name my-nginx -p 8080:80 nginx
Key options
-it runs the container interactively
-d runs the container in the background
–name assigns a readable name to the container
-p maps host ports to container ports
docker ps
Purpose
Lists containers.
Usage
docker ps
docker ps -a
docker ps shows running containers only.
docker ps -a includes stopped containers.
docker stop and docker start
Purpose
Stops or starts an existing container.
Usage
docker stop my-container
docker start my-container
docker rm
Purpose
Removes a stopped container.
Usage
docker rm my-container
docker inspect
Purpose
Displays low-level JSON metadata for containers or images.
Typical use cases
Inspect environment variables, network settings, mounts, ports, and runtime configuration.
Usage
docker inspect my-container
Executing Commands in Running Containers
docker exec
Purpose
Runs a command inside a running container.
Interactive shell
docker exec -it my-container bash
docker exec -it my-container sh
One-off command
docker exec my-container ls /etc
Logs and Runtime Monitoring
docker logs
Purpose
Displays standard output and error logs from a container.
Usage
docker logs my-container
docker logs -f my-container
docker logs –tail 50 my-container
docker stats
Purpose
Shows real-time CPU, memory, network, and disk usage for containers.
Usage
docker stats
docker stats my-container
Images and Registries
docker pull
Purpose
Downloads an image from a container registry.
Usage
docker pull ubuntu
docker pull nvcr.io/nvidia/pytorch:24.04-py3
docker images
Purpose
Lists all locally available images.
Usage
docker images
docker tag
Purpose
Creates an additional name and tag for an image, commonly used before pushing to a registry.
Usage
docker tag nginx myuser/nginx:demo
docker push
Purpose
Uploads an image to a container registry.
Usage
docker push myuser/nginx:demo
Prerequisite
You must authenticate with the registry using docker login.
Cleanup and Disk Management
docker system df
Purpose
Displays Docker disk usage information.
Usage
docker system df
docker container prune
Purpose
Removes all stopped containers.
Usage
docker container prune
docker image prune
Purpose
Removes dangling and unused images.
Usage
docker image prune
docker system prune
Purpose
Removes unused containers, networks, images, and build cache.
Usage
docker system prune
Aggressive cleanup
docker system prune -a –volumes
This removes all unused images and volumes and should be used with caution.
Docker Contexts
docker context ls
Purpose
Lists available Docker contexts such as local, desktop, or remote environments.
Usage
docker context ls
docker context use
Purpose
Switches the active Docker context.
Usage
docker context use desktop-linux
