[bsharper]

I just use JS scripts, because if node is not installed you aren't getting very far anyway.

Actions like "copy this file", "clear this subdirectory", and "pull these files over the network" are easy to write synchronously in node, are there are modules for things that aren't.

For more complex actions, there are modules like env-cmd or cross-env for setting environmental variables on different platforms. If you had something really complex, you could check os.platform() and then call scripts written for each OS.

But you're right, you can't write a .sh shell script and expect it to magically work on Windows.