linux.recipes - Your Linux Command Reference
BashSheet - Greg's Wiki
Terminal Trove - The $HOME of all things in the terminal.
Terminal Trove showcases the best of the terminal, Discover a collection of CLI, TUI, and more developer tools at Terminal Trove.
bobbyiliev/introduction-to-bash-scripting: Free Introduction to Bash Scripting eBook
Free Introduction to Bash Scripting eBook.