DUP(2)                                                     DUP(2)

     NAME
          dup, dup2 - duplicate an open file descriptor

     SYNOPSIS
          dup(fildes)
          int fildes;

          dup2(fildes, fildes2)
          int fildes, fildes2;

     DESCRIPTION
          Given a file descriptor dup allocates another file descrip-
          tor synonymous with the original.  The new file descriptor
          is returned.

          In the second form of the call, fildes is a file descriptor
          referring to an open file, and fildes2 is a non-negative
          integer less than the maximum value allowed for file
          descriptors (currently 127).  Dup2 causes fildes2 to refer
          to the same file as fildes. If fildes2 already referred to
          an open file, it is closed first.

     SEE ALSO
          creat(2), open(2), close(2), pipe(2)

     DIAGNOSTICS
          The value -1 is returned if: the given file descriptor is
          invalid; there are already too many open files.