In the Scouts you get badges for the things you learn, and you show them off by wearing them on your sleeve, once a parent has stitched them on.
Lately I’ve started curating aliases in bashrc. For anyone who hasn’t used it, it’s a file in which you can store settings for controlling your computer, including abbreviated versions of commands you use a lot (aliases). Some people like to share these files, or snippets from them, to give other programmers ideas for which shortcuts to include in their own collection.
The nature of the file lends itself well to this sharing. You do the work of learning some new command, practise using it until it is part of your everyday toolkit, and then make a shorter reference to it. These references become a list of what you know and can do, and a neat little resume of your command line experience.