I've read reports on the incompatibilities, but the odd part is that you can popen which, under FreeBSD at least, is a fairly thin wrapper around vfork() and ex

I've read reports on the incompatibilities, but the odd part is that you can popen which, under FreeBSD at least, is a fairly thin wrapper around vfork() and execve() makes that feel suspect. It may be a bit more work, but commands like this still should be treated as special.