The error message indicates that you have not installed bash
, or it is not in your PATH
.
The top Google hit is http://win-bash.sourceforge.net/ but you also need to understand that most Bash scripts expect a Unix-like environment; so just installing Bash is probably unlikely to allow you to run a script you found on the net, unless it was specifically designed for this particular usage scenario. The usual solution to that is https://www.cygwin.com/ but there are many possible alternatives, depending on what exactly it is that you want to accomplish.
If Windows is not central to your usage scenario, installing a free OS (perhaps virtualized) might be the simplest way forward.
The second error message is due to the fact that Windows nominally accepts forward slash as a directory separator, but in this context, it is being interpreted as a switch separator. In other words, Windows parses your command line as app /build /build.sh
(or, to paraphrase with Unix option conventions, app --build --build.sh
). You could try app\build\build.sh
but it is unlikely to work, because of the circumstances outlined above.