Although geared toward beginners, many of us might find this series of Linux tutorials (https://www.guru99.com/introduction-linux.html) a good refresher for terminal commands as well.
Good info, thanks Jason.
This introduction must be very old. It refers to Ubuntu 16.04 and VirtualBox 4.3, and even to Ubuntu 12.10 in one place.
It probably is. However, I think it's being pedantic to worry about those things as I see them only in the screenshots and the links lead to the latest versions of Ubuntu LTS and Virtualbox. They should probably say to download the latest version though and not the version they show in the screenshots but I think that most people could still figure it out from the links.