Did you not even try the original command? As you've now updated it (https://github.com/little-book-of/c/commit/43b0a89852a507bdd...), it is definitely not one simple flag since arm-linux-gnueabihf-gcc has to be installed from somewhere. It doesn't exist in a default installation of GCC that only targets the host, and you'll need to install a GCC version for every architecture you want to target.