Ask HN: What kind of Software "Jigs" do you have?

In woodworking and other crafts there are Jigs that are used and built for the purpose of creating something else - it's a tool or a device specifically made to and while making something else.

Do you have such Jigs in software? if so what kind of jigs do you use? How do you use them?

Do Makefiles count?

I set up various incantations like:

make build

make run

make test

make lint

There are a lot of code generators, like lex/flex, bison/yacc, re2c, ragel, lemon, antlr, gperf, xxd. Maybe they don't count because they're pre-existing tools, but you can see how they might have started as a one-off tool and grew from there. I've written plenty of my own, either to generate code or generate tables of data at compile time.