Imagine you had all your build commands in a shell-script. Now imagine that you want to run individual steps from time-to-time, instead of running your whole s

Imagine you had all your build commands in a shell-script. Now imagine that you want to run individual steps from time-to-time, instead of running your whole script start to finish. So maybe you write functions that represent each group of commands, and call the function based on an input argument. Now imagine that some of your build-steps have dependencies on other build-steps, and you want to be able to say "run step X, plus whatever else you have to do first." Or maybe you want to retry a failed build from wherever it left off, instead of having to re-run the entire thing. Now imagine that you'd like to have some level of isolation between build-steps, so that one step doesn't mess the other one up. As you add more and more things to your build script, you'll find yourself writing an implementation of Make pretty quickly. Now - sometimes - your build fails halfway though, and you want to resume from where-ever it failed. S