ryanwhocodes Feb 11, 2018 · 3 min read

Top 10 Docker CLI commands you can’t live without

A beginners' guide to 10 useful docker CLI commands.

Docker is a great tool for building microservices, allowing you to create cloud-based applications and systems. To make the most of it via your terminal, here is a run down of the top 10 Docker commands for your terminal.

Contents

Docker key concepts

A container is launched by running an image. An image is an executable package that includes everything needed to run an application – the code, a runtime, libraries, environment variables, and configuration files.

A container is a runtime instance of an image–what the image becomes in memory when executed (that is, an image with state, or a user process). You can see a list of your running containers with the command, docker ps, just as you would in Linux.

Docker Concepts

Top 10 CLI commands

1. ps

Lists running containers. Some useful flags include: -a, -all for all containers (default shows just running) and —-quiet, -q to list just their ids (useful for when you want to get all the containers).

2. pull

Most of your images will be created on top of a base image from the Docker Hub registry. Docker Hub contains many pre-built images that you can pull and try without needing to define and configure your own. To download a particular image, or set of images (i.e., a repository), use docker pull.

3. build

The docker build command builds Docker images from a Dockerfile and a “context”. A build’s context is the set of files located in the specified PATH or URL. Use the -t flag to label the image, for example docker build -t my_container . with the . at the end signalling to build using the currently directory.

4. run

Run a docker container based on an image, you can follow this on with other commands, such as -it bash to then run bash from within the container.

5. logs

Use this command to display the logs of a container, you must specify a container and can use flags, such as --follow to follow the output in the logs of using the program. docker logs --follow my_container.

6. volume

This lists the volumes, which are the preferred mechanism for persisting data generated by and used by Docker containers.

7. rm

Removes one or more containers, such as docker rm my_container.

8. rmi

Removes one or more images. docker rmi my_image

9. stop

Stops one or more containers. docker stop my_container stops one container, while docker stop $(docker ps -a -q) stops all running containers. A more direct way is to use docker kill my_container, which does not attempt to shut down the process gracefully first.

10. Use them together

For example, to clean up all your docker images and containers:

  • kill all running containers with docker kill $(docker ps -q)
  • delete all stopped containers with docker rm $(docker ps -a -q)
  • delete all images with docker rmi $(docker images -q)

Find out more

There are lots more Docker commands, flags and combinations you can learn about in Docker’s CLI Documentation. Keep trying them out and they should become second nature.

This is just the start though, docker-compose is a tool to define multiple docker containers that work together in an application.