As always, It Depends.

If I have plenty of time on my hands, and I'm interested in learning about fork/exec, then sure, I'll roll my own. I'm in this game to solve interesting problems, even if they've already been solved a billion times.

Otherwise, it depends on what modules are out there. If there's one that fits my needs (doesn't have a horribly broken interface or implementation, has all the features I want, doesn't make assumptions that aren't valid for my project, etc), I'll use it. If one of the existing modules is "close enough" to what I want, I'll patch it. Otherwise I'm pretty much stuck writing code from scratch.

In this case, since I've already been introduced to fork(2) and friends, I'd probably use an existing module.

--
The hell with paco, vote for Erudil!
:wq