Docker is container software. It is commonly used as a lightweight alternative to a virtual machine. 

Running Docker Without sudo

By default, Docker has to be run with sudo commands otherwise you will experience errors such as:

(this particular error was trying to run docker pull ...)

  1. Create a new docker group:
    sudo groupadd docker 
  2. Add the current user (you) to the docker group:
  3. Restart the docker service:
  4. Apply the changed settings to the current terminal process (logging out and back in would have the same effect):
  5. All done! You should now be able to use docker commands without sudo.

What Are Images? What Are Containers?

An image is a file which contains all the information/data about a particular system setup. When you run an image, you create a container of this image. You can create many containers based of the same image.

Getting Images (docker pull)

Images can be downloaded from Docker Hub using the docker pull command.

Images can be removed with:

Inspecting Local Images

You can view all of the docker images present on the local machine with:



To show only running containers:

To show all containers (included those that are not running):

To Start A New Bash Session Within A Container

Enter this on the a shell session running in the host computer to enter a shell session inside the docker container.

To Exit A Container Without Stopping It

If the container is being run inside a bash shell, you can press Ctrl-P then Ctrl-Q.