@Zanna Do you want to post an answer about how the syntax errors they're getting are from running their C++ source code file as though it were a shell script. I don't think C++ knowledge is needed for this. I was hoping to include that in my own answer. But my own answer -- assuming I even manage to post it! -- is looking like it will be plenty long even without that.

@EliahKagan sure, if it's still needed after you've written your answer or when I get up tomorrow

@Zanna By my overly verbose standards, I could fit something about it in my answer. But I want to be able to expand my answer later if the OP provides more information, without sacrificing its readability and usefulness to other people who are in mostly the same situation but with differing specifics. So I think it's best that I leave some room in my answer. I will know this for sure if and when I actually finish the answer, read it over, and decide if I should submit it.