Armin Briegel's book macOS Terminal and shell is a great place to start as well as his website Scripting OS X and other books he has written. Additionally tutorials on YouTube, and courses on Udemy and CodeAcademy have been a help as well as books f...
For me it's scripting. While I can find, read, modify and use scripts that others have created, actually creating my own scripts is one if not my biggest weakness in my toolbox. However, I continue to read and learn how to write scripts from scratc...
