dup(2)                     DG/UX 4.30                      dup(2)



     NAME
          dup - Duplicate an open file descriptor.

     SYNOPSIS
          int    dup  (fildes)
          int             fildes;

     PARAMETERS
          fildes         A valid, active file descriptor.

     DESCRIPTION
          If <fildes> is a valid, active descriptor, then this call
          returns a new file descriptor with both descriptors sharing
          the same object pointer.  The new descriptor is set to
          remain open across exec system calls.  This call is
          identical to new_filedes = fcntl (filedes, F_DUPFD, 0).

     ACCESS CONTROL
          None.

     RETURN VALUE
          0..<NOFILE-1>  The value of the new file descriptor.


          -1             An error occurred.  Errno is set to indicate
                         the error.

     EXCEPTIONS
          Errno may be set to one of the following error codes:


          EBADF          <Fildes> is not a valid, active descriptor.


          EMFILE         All descriptors are open.

     SEE ALSO
          The related manual sections:  accept(2), close(2), creat(2),
          dup2(2), exec(2), fcntl(2), getdtablesize(2), open(2),
          pipe(2), socket(2), socketpair(2).

     STANDARDS
          When using m88kbcs as the Software Development Environment
          target, the dup function will be emulated using the fcntl(2)
          system call. Since this is an emulation, a slight
          performance degradation may be noticed in comparison to
          using dup in /lib/libc.a.








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