Transformation of text is surprisingly easy on Unix and wannabe-Unix thanks to the concept of pipes. tr, sed and awk are still incredibly useful once you understood how they act.
The "GCC one" is not a "C one" though. It took me a while to notice that you're not talking about preprocessors.

Apropos: C happens to have built-in (sort of) macro processing as of C11 via _Generic. That's actually kind of sweet. For all other usages like that I found myself to (ab)use Perl which pretty much does anything sed/awk/... does.

By the way: lexers and macro processors are not necessarily the same thing.