Linux post-installation steps for Docker Engine

To create the docker group and add your user:

Create the docker group.
```
sudo groupadd docker
```
Add your user to the docker group.
```
sudo usermod -aG docker $USER
```
Log out and log back in so that your group membership is re-evaluated.

If you're running Linux in a virtual machine, it may be necessary to restart the virtual machine for changes to take effect.

You can also run the following command to activate the changes to groups:
```
newgrp docker
```
Verify that you can run docker commands without sudo.
```
docker run hello-world
```
This command downloads a test image and runs it in a container. When the container runs, it prints a message and exits.