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# Docker Command Manual: Complete Reference Guide Docker is an open-source platform designed to help developers build, ship, run, and manage applications within lightweight, isolated environments called containers. This comprehensive manual serves as a quick-reference guide for the most frequently used Docker commands, categorized by their functional areas: container lifecycle management, image operations, networking, volumes, and Docker Compose. --- ## 1. Container Lifecycle Management These commands control the state transitions of a container, from creation and execution to pausing, stopping, and deletion. | Command | Description | Common Syntax | | :--- | :--- | :--- | | **`run`** | Creates and starts a new container from an image. | `docker run image ` | | **`start`** | Starts one or more stopped containers. | `docker start container [container...]` | | **`stop`** | Gracefully stops one or more running containers. | `docker stop container [container...]` | | **`restart`** | Restarts one or more running containers. | `docker restart container [container...]` | | **`kill`** | Immediately terminates (SIGKILL) one or more running containers. | `docker kill container [container...]` | | **`rm`** | Removes one or more stopped containers. | `docker rm container [container...]` | | **`pause`** | Suspends all processes within one or more containers. | `docker pause container [container...]` | | **`unpause`** | Resumes all processes within one or more paused containers. | `docker unpause container [container...]` | | **`create`** | Creates a new container but does not start it. | `docker create image ` | | **`exec`** | Runs a new command inside an active, running container. | `docker exec container command [args...]` | | **`rename`** | Renames an existing container. | `docker rename container new_name` | ### Code Examples ```bash # Run an Nginx container in the background (detached mode) and map port 80 docker run -d -p 8080:80 --name my-nginx nginx # Execute an interactive bash shell inside the running Nginx container docker exec -it my-nginx /bin/bash # Stop and remove the container docker stop my-nginx docker rm my-nginx ``` --- ## 2. Container Operations & Monitoring These commands are used to inspect, monitor, and interact with active or inactive containers. | Command | Description | Common Syntax | | :--- | :--- | :--- | | **`ps`** | Lists containers (defaults to running containers only). | `docker ps ` | | **`inspect`** | Returns low-level, detailed JSON information on Docker objects. | `docker inspect name|id [name|id...]` | | **`top`** | Displays the running processes of a container. | `docker top container ` | | **`attach`** | Attaches local standard input, output, and error streams to a running container. | `docker attach container` | | **`events`** | Gets real-time events from the Docker daemon. | `docker events ` | | **`logs`** | Fetches and views the log output of a container. | `docker logs container` | | **`wait`** | Blocks until one or more containers stop, then prints their exit codes. | `docker wait container [container...]` | | **`export`** | Exports a container's filesystem as a tar archive. | `docker export container` | | **`port`** | Lists port mappings or a specific mapping for the container. | `docker port container [private_port]` | | **`stats`** | Displays a live stream of container resource usage statistics (CPU, Memory, Network). | `docker stats [container...]` | | **`update`** | Dynamically updates resource configurations (CPU, memory limits) of a container. | `docker update container [container...]` | ### Code Examples ```bash # List all containers, including stopped ones docker ps -a # View the last 50 lines of a container's logs and follow the output in real-time docker logs --tail 50 -f my-nginx # Monitor CPU and memory usage of all running containers docker stats ``` --- ## 3. Container Root Filesystem (rootfs) Operations These commands manage the files and directories inside a container's filesystem layer. | Command | Description | Common Syntax | | :--- | :--- | :--- | | **`commit`** | Creates a new image from a container's current changes. | `docker commit container [repository[:tag]]` | | **`cp`** | Copies files/folders between a container and the local filesystem. | `docker cp container:src_path dest_path` | | **`diff`** | Inspects changes to files or directories on a container's filesystem. | `docker diff container` | ### Code Examples ```bash # Copy a local configuration file into a container docker cp ./nginx.conf my-nginx:/etc/nginx/nginx.conf # Check what files have changed in the container since it was started docker diff my-nginx ``` --- ## 4. Image Registry Operations These commands manage authentication and image transfers between your local Docker engine and remote registries (such as Docker Hub or private registries). | Command | Description | Common Syntax | | :--- | :--- | :--- | | **`login`** | Log in to a Docker registry. | `docker login ` | | **`logout`** | Log out from a Docker registry. | `docker logout ` | | **`pull`** | Pulls (downloads) an image or a repository from a registry. | `docker pull name[:tag|@digest]` | | **`push`** | Pushes (uploads) an image or a repository to a registry. | `docker push name[:tag]` | | **`search`** | Searches Docker Hub for images. | `docker search term` | ### Code Examples ```bash # Log in to a private registry docker login registry.example.com # Pull the latest Ubuntu image from Docker Hub docker pull ubuntu:latest # Push a tagged image to your repository docker push username/my-app:v1.0 ``` --- ## 5. Local Image Management These commands manage the lifecycle of Docker images stored locally on your host machine. | Command | Description | Common Syntax | | :--- | :--- | :--- | | **`images`** | Lists locally stored Docker images. | `docker images [repository[:tag]]` | | **`rmi`** | Removes one or more local images. | `docker rmi image [image...]` | | **`tag`** | Creates a tag (alias) pointing to a target image. | `docker tag source_image[:tag] target_image[:tag]` | | **`build`** | Builds a Docker image from a Dockerfile. | `docker build path | url | -` | | **`history`** | Shows the history of an image, including its layers. | `docker history image` | | **`save`** | Saves one or more images to a tar archive (useful for offline transfers). | `docker save image [image...]` | | **`load`** | Loads an image from a tar archive or STDIN. | `docker load ` | | **`import`** | Imports the contents from a tarball to create a filesystem image. | `docker import file|URL|- [repository[:tag]]` | ### Code Examples ```bash # Build an image from a Dockerfile in the current directory docker build -t my-custom-app:1.0 . # Save an image to a tar file docker save -o my-image.tar my-custom-app:1.0 # Load the image on another machine docker load -i my-image.tar ``` --- ## 6. System Information & Versioning These commands provide diagnostic information about your Docker environment. | Command | Description | Common Syntax | | :--- | :--- | :--- | | **`info`** | Displays system-wide information regarding the Docker installation. | `docker info` | | **`version`** | Shows the Docker version information for both client and server. | `docker version` | --- ## 7. Docker Compose Commands Docker Compose is a tool for defining and running multi-container Docker applications. Below are the essential commands for managing multi-container environments. | Command | Description | | :--- | :--- | | **`docker compose run`** | Runs a one-off command on a service defined in your compose file. | | **`docker compose rm`** | Removes stopped service containers. | | **`docker compose ps`** | Lists containers associated with the compose project and their states. | | **`docker compose build`** | Builds or rebuilds services defined in the compose file. | | **`docker compose up`** | Builds, (re)creates, starts, and attaches to containers for a service. | | **`docker compose ls`** | Lists running compose projects. | | **`docker compose start`** | Starts existing containers for a service. | | **`docker compose restart`** | Restarts service containers. | | **`docker compose down`** | Stops and removes containers, networks, volumes, and images created by `up`. | ### Code Examples ```bash # Start all services defined in docker-compose.yml in the background docker compose up -d # Check the status of the services docker compose ps # Stop and clean up containers and networks docker compose down ``` --- ## 8. Network Management Docker networks enable containers to communicate with each other and with the host machine or external networks. | Command | Description | | :--- | :--- | | **`docker network ls`** | Lists all networks managed by Docker. | | **`docker network create `** | Creates a new user-defined network (e.g., bridge, overlay). | | **`docker network rm `** | Removes one or more networks. | | **`docker network connect `** | Connects a running container to a network. | | **`docker network disconnect `** | Disconnects a container from a network. | ### Code Examples ```bash # Create a custom bridge network docker network create my-custom-net # Connect an existing container to the new network docker network connect my-custom-net my-nginx ``` --- ## 9. Volume Management Volumes are the preferred mechanism for persisting data generated by and used by Docker containers. | Command | Description | | :--- | :--- | | **`docker volume ls`** | Lists all local volumes. | | **`docker volume create `** | Creates a new named volume. | | **`docker volume rm `** | Removes one or more volumes (must not be in use by any container). | | **`docker volume inspect `** | Displays detailed information about a specific volume. | ### Code Examples ```bash # Create a persistent volume for database storage docker volume create db-data # Inspect the volume to find its mount point on the host docker volume inspect db-data ``` --- ## Considerations & Best Practices 1. **Container Ephemerality**: Containers should be treated as ephemeral. Never store critical application data inside a container's writable layer; always use **Docker Volumes** or **Bind Mounts** to persist data. 2. **Resource Limits**: When running containers in production, always use resource limit flags (e.g., `--memory` and `--cpus` in `docker run` or `docker update`) to prevent a single container from consuming all host resources. 3. **Clean Up Unused Resources**: Docker can consume significant disk space over time. Use the system prune command regularly to clean up dangling resources: ```bash # Remove stopped containers, unused networks, dangling images, and build caches docker system prune -f # To also clean up unused volumes: docker system prune --volumes -f ```