Running an editor from ANSI C

I'm writing a shell in pure ANSI C, that oerates on FileSystem XML files.
So it's a great amount of fun. The BBXFS shell.
Except a real shell runs external programs. Which I have to do to all you to edit text files. Because a shell is no good if you can't edit text files easily, and theres no way of doing that in pure C due to the limitations of stdin.
So I just call system with nano. And it works. But it's hardly robust, and I'd like to get this right.
Check out the shell at
https://github.com/MalcolmMcLean/babyxrc
--
Check out Basic Algorithms and my other books:
https://www.lulu.com/spotlight/bgy1mm