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 {OPEN_MAX} (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
                        {OPEN_MAX}.

         EINTR          a signal was caught during the dup2 call.

         %[EMFILE       {OPEN_MAX} 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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