Starting with macOS Catalina Zsh shell comes pre installed https://support.apple.com/en-us/HT208050
Moving to zsh https://scriptingosx.com/2019/06/moving-to-zsh/
Oh My Zsh - a delightful & open source framework for Zsh https://ohmyz.sh/#install
Robby Russell, created - Oh My Zsh https://www.planetargon.com/about/robby-russell
How to Configure your macOs Terminal with Zsh like a Pro
Note: This page also has the command line syntax to install the iTerm Robby Russell theme. https://www.freecodecamp.org/news/how-to-configure-your-macos-terminal-with-zsh-like-a-pro-c0ab3f3c1156/
iTerm2 - macOS Terminal Replacement https://www.iterm2.com/
Version 3 - iTerm2 - macOS Terminal Replacement https://www.iterm2.com/version3.html
Learn Zsh in 80 Minutes macOS - Oh My Zsh - Command Line Power User | https://www.youtube.com/watch?v=MSPu-lYF-A8
How to see hidden files and folders in macOS | AppleInsider for macOS versions older than Sierra.
Caution when doing this, not to change or delete important hidden system-files! https://appleinsider.com/articles/18/07/27/how-to-see-hidden-files-and-folders-in-macos