Docker Command Line Survival Guide: The Absolute Basics- 4 mins
A brief introduction to ten essential and absolute basic Docker commands to get you started, and keep you going in the command-line interface.
In this post, I decided to share some of the basic commands you might need to get started with Docker. This is neither an extensive list of the commands available, nor all of the commands you might need. This is merely me sharing a prettified list of my cheat sheet for Docker basics with you.
Before we get started, it might be a good idea to note that all of the commands below are written without
sudo. If your installation is not running without
sudo (assuming that you are running Linux), you might want to check out the post-installation guide for Linux in the Docker docs.
1. Check if Everything Works
First things first, you can use this simple command to check that your installation is fine. Note: Make sure you have right CPU architecture for your images. Raspberry Pi (ARM) things will not run on x86 architecture, and vice versa.
For Raspberry Pi / AMD:
2. List Containers
After creating containers, first thing you might want to do is to see what containers you have up and running. To list all running containers you can use:
This command will give you a list similar to this:
However, it will not show you any stopped containers. To list all local containers use the
The output will be more like this (note that is shows also stopped, or even failed containers):
docker ps in the Docker docs.
3. List Images
To list all the images available on your system, simply do this:
4. Containers vs. Images?
What is the difference between containers and images, you might wonder? Well, I have a link for you. This will hopefully help you to understand how Docker manages the data within your images and containers.
5. Starting and Stopping Containers
docker run command first creates a writeable container layer over the specified image, and then starts it using the specified command. That is,
docker run is equivalent to the API’s
/containers/create, and then
Commands, Files, and Folders Inside a Container
6. Run Any Command from a Container
You can run any command in a running container just knowing its ID (or name):
7. Getting Into Containers
Since you can run any command, then you can (obviously) also run a shell from a container; if you have any. This will be a bit similar to running an
ssh command to connect remotely to a regular Linux box (given you have
sh in the container):
8. Copy Files From and To Containers
Another useful trick you might need is to copy some files to and from a container. Your friend here is the
docker cp command (link to the docs):
After playing round with all the images and containers, you might realize that you have quite a collection of these on your drive, just taking up space.
9. Remove Containers
To remove the unused or unwanted containers, you can run the
docker rm command with the IDs of those images. The IDs can be retrieved with the
docker ps -a command, mentioned above.
10. Remove Images
docker rmi command followed by the IDs of images will help you to remove the unused or unwanted images. The abovementioned
docker images command will help you finding the correct IDs for the images in question.