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dup(2)                           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  descrip-
                       tor.



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



       EMFILE          The process has too many open files (see getrlimit(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                       to that machine is no longer active.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 attributes:


       tab()     allbox;     cw(2.750000i)|    cw(2.750000i)    lw(2.750000i)|
       lw(2.750000i).  ATTRIBUTE TYPEATTRIBUTE VALUE Interface  StabilityStan-
       dard MT-LevelAsync-Signal-Safe


SEE ALSO
       close(2),  creat(2), exec(2), fcntl(2), getrlimit(2), open(2), pipe(2),
       dup2(3C), lockf(3C), attributes(5), standards(5)



SunOS 5.10                        28 Dec 1996                           dup(2)