Makes sense, but I'm still afraid if I don't use it daily I will tend to forget it. I have learned everything I know by doing it in practice, so personally unless I would take some huger type of side project to learn up bash I don't see how I could do it. And in the end if I'm working with other frontend devs, I'd also have to convince them to learn bash as opposed to just using JavaScript/TypeScript for scripting.

Do you have any suggestions on how one should go about learning it?

If I do some course right now, then in a year's time if I use it maybe on few occasions in a year, I won't remember it, and it will stop being practical again.