dup2(3C)                         UNIX System V                         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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