[pickledcods]

Do not forget the notes on dup2(). It's about the automatic closing of newfd before it gets replaced. I've bumped into this situation several times, that is why I'm mentioning it.

  SYNOPSIS
   int dup2(int oldfd, int newfd);

  NOTES:
  If newfd was open, any errors that would have been reported at close(2) time are lost.
  If this is of concern, then the correct approach is not to close newfd before calling dup2(),
  because of the race condition described above.
  Instead, code something like the following could be used:

   /* Obtain a duplicate of 'newfd' that can subsequently
      be used to check for close() errors; an EBADF error
      means that 'newfd' was not open. */

   tmpfd = dup(newfd);
   if (tmpfd == -1 && errno != EBADF) {
       /* Handle unexpected dup() error */
   }

   /* Atomically duplicate 'oldfd' on 'newfd' */

   if (dup2(oldfd, newfd) == -1) {
       /* Handle dup2() error */
   }

   /* Now check for close() errors on the file originally
      referred to by 'newfd' */

    if (tmpfd != -1) {
       if (close(tmpfd) == -1) {
           /* Handle errors from close */
       }
   }