Quick reference, not a course. If you already know the tool and just need a fast lookup for a specific command or function, start here instead of the Skill Guides.
The shell commands you'll actually reach for day to day.
Version control commands, from your first commit to resolving a merge conflict.
Aggregate, window, string and date functions, grouped by what they do.
Core built-ins plus the pandas methods you'll use in almost every script.