[i15e]

I'm not seeing any ? marks in my code. Are you referring to the instances of $'\t'? In bash (and other shells, including recent versions of the POSIX sh specification) $'...' is treated like a C-style string complete with backslash escape sequences, so $'\t' is a way to have a tab character as a part of a command argument.

[jcgl]

Oops, yes, I don't know why I mistyped a question mark. That's exactly what I was wondering, thanks.