Although DrByte is "da man" when it comes to serving up Zen Cart, it's at least possible that the OP was actually trying to use a Mac as a "real webserver". Mac OS X comes in two flavours, one for the usual personal computer uses and one -- called conveniently enough, Mac OS X Server -- for use as a server. It is a highly capable server -- in effect a BSD Unix box -- that has all the usual capabilities of such machines.

The OP didn't say what he was using and may even have posted in the wrong forum, but assuming he is using a Mac, and even assuming he's using Mac OS X Server, his question remains worrisome. I have to go with the good Doctor's advise, which I'll paraphrase as... If you have to ask that question, you probably shouldn't be doing what you're doing.

Rob