NAME
          fd_copy - duplicate a descriptor

     SYNTAX
          #include <fd.h>

          int fd_copy(to,from);

          int to;
          int from;

     DESCRIPTION
          fd_copy copies descriptor from to descriptor to.  If to was
          already open, fd_copy closes it.  fd_copy always leaves from
          intact; if to and from are the same number, fd_copy does
          nothing.

          fd_copy returns 0 on success, -1 on error.  fd_copy does not
          guarantee that to will remain open, if it was open, in case
          of error.

     SEE ALSO
          dup(2), fd_move(3)