System Calls                                               dup(2)


NAME

     dup - duplicate an open file descriptor


SYNOPSIS

     #include <unistd.h>

     int dup(int fildes);


DESCRIPTION

     The dup() function returns a new file descriptor having  the
     following  in  common with the original open file descriptor
     fildes:

         o    same open file (or pipe)

         o    same file pointer (that is, both  file  descriptors
              share one file pointer)

         o    same access mode (read, write or read/write).

     The new file descriptor is set to remain  open  across  exec
     functions (see fcntl(2)).

     The file descriptor returned is the lowest one available.

     The dup(fildes) function call is equivalent to:

     fcntl(fildes, F_DUPFD, 0)


RETURN VALUES

     Upon   successful   completion,   a   non-negative   integer
     representing  the file descriptor is returned. Otherwise, -1
     is returned and errno is set to indicate the error.


ERRORS

     The dup() function will fail if:

     EBADF      The fildes argument is  not  a  valid  open  file
                descriptor.

     EINTR      A signal was caught during the execution  of  the
                dup() function.

     EMFILE     The  process  has  too  many  open   files   (see
                getrlimit(2)).

SunOS 5.11          Last change: 28 Dec 1996                    1


System Calls                                               dup(2)

     ENOLINK    The fildes argument is on a  remote  machine  and
                the link to that machine is no longer active.


ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Standard                    |
    |_____________________________|_____________________________|
    | MT-Level                    | Async-Signal-Safe           |
    |_____________________________|_____________________________|


SEE ALSO

     close(2),   creat(2),   exec(2),   fcntl(2),   getrlimit(2),
     open(2),  pipe(2), dup2(3C), lockf(3C), attributes(5), stan-
     dards(5)

SunOS 5.11          Last change: 28 Dec 1996                    2


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