I have looked for these things multiple times. Guide on Zone.ee page – really good. List of common SSH commands on Mediatemple page. Useful guide on how to Set Up SSH Keys on Ubuntu 18.04 DigitalOcean page.
Some very basic commands
Print list of directories only.
ls -d */
Get public key in Ubuntu terminal.
rm -rf foldername/
Zip folder (found it here)
zip -r filename.zip foldername/
What is it good for?
I have mainly found myself using it for deleting large set of files which either crash or take too much time to delete by using FTP. For example when deleting Magento, WP or Prestashop installations 🙂