Here's a fairly simple thousand line Makefile: https://github.com/simonmichael/hledger/blob/2d35b1051/Makef... (and https://github.com/simonmichael/hledger/blob/2d35b1051/Makef...)

that was converted to a Justfile: https://github.com/simonmichael/hledger/blob/43c93eb37/Justf...

And here's a more powerful kind of makefile using a full programming language: https://github.com/simonmichael/hledger/blob/43c93eb37/Shake...

And here are two multicommand shell scripts:

https://github.com/simonmichael/hledger/blob/43c93eb37/bin/f...

https://github.com/simonmichael/hledger/blob/43c93eb37/bin/t...

that were converted to a justfile: https://github.com/simonmichael/hledger/blob/43c93eb37/bin/j...