dup2(3C)                                                 dup2(3C)



NAME
     dup2 - duplicate an open file descriptor

SYNOPSIS
     #include <unistd.h>

     int dup2 (int fildes, int fildes2);

DESCRIPTION
     fildes is a file descriptor referring to an open  file,  and
     fildes2  is a non-negative integer less than {OPENMAX} (the
     maximum number of open files).  dup2 causes fildes2 to refer
     to  the  same file as fildes. If fildes2 already referred to
     an open file, not fildes, it is closed  first.   If  fildes2
     refers  to  fildes,  or  if  fildes is not a valid open file
     descriptor, fildes2 will not be closed first.

     dup2 will fail if one or more of the following are true:

     EBADF          fildes is not a valid open file descriptor.

     EBADF          fildes2 is negative or greater than or  equal
                    to {OPENMAX}.

     EINTR          a signal was caught during the dup2 call.

     %[EMFILE       {OPENMAX}  file  descriptors  are  currently
                    open.

SEE ALSO
     creat(2), close(2),  exec(2),  fcntl(2),  open(2),  pipe(2),
     lockf(3C), limits(4).

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


















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