I couldn't find anything that solved those problems without lots of extra machinery. I understand why, shell scripts are generally not long, and focused on a dedicated task; adding cli features to them is mostly unnecessary, many might even discourage it for many valid reasons.

Nonetheless, I considered writing this functionality myself, but that felt like a poor use of company time. So I started toying with what a framework to handle those concerns entirely in shell script would look like on the side. Thus, shifu was born. I've been working on it off and on for about a year, and think I've got a reasonable alpha release, so thought I'd share.