Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> I guess the other possibility is that there exists an operating system
> that returns file descriptors higher than its FD_SETSIZE, when some fds
> below FD_SETSIZE are still available. Doesn't seem realistic.
I think POSIX requires open() to select the lowest unused FD. Otherwise
tricks like closing and reopening stdout wouldn't work reliably.
regards, tom lane