Unix Tutorials
List of Unix Tutorial Web Sites
I have not yet been able to review all of these sites for quality, but on first look they seem decent enough.
http://www1.udel.edu/it/help/unix/filemgmt.html
https://ubuntu.com/tutorials/command-line-for-beginners#1-overview
https://www.javatpoint.com/linux-tutorial
http://www.ee.surrey.ac.uk/Teaching/Unix/
https://www.tutorialspoint.com/unix/index.htm#
https://ryanstutorials.net/linuxtutorial/
https://www.guru99.com/unix-linux-tutorial.html
Cheat Sheets
I have my own cheatsheet page. Another of my pages has some Unix help.
A useful command list because it starts with file and directory commands, what most people need to start with.