@JeffSchaller, your deleting of half of the answers at
unix.stackexchange.com/q/653844 seems arbitrary and unwarranted to me here. The question is to explain how some code does X + Y. Some answers explain why it does X and not Y and how to do X + Y (which in the end looks like what the OP wants), the questions you deleted suggest alternative ways to do X + Y without repeating why the original code does only X as that would be redundant.