PROGRAM mpi2io

     USE MPI
     IMPLICIT none

     INTEGER :: myrank, nproc,ierr;
     INTEGER, PARAMETER :: dim_buf = 10
     INTEGER :: buf(dim_buf)
     INTEGER :: i, intsize;
     INTEGER(KIND=MPI_OFFSET_KIND) :: offset, file_size
     INTEGER :: fh
     INTEGER :: status(MPI_STATUS_SIZE)
     INTEGER :: filetype

     CALL MPI_Init(ierr);
     CALL MPI_Comm_size(MPI_COMM_WORLD,nproc,ierr)
     CALL MPI_Comm_rank(MPI_COMM_WORLD,myrank,ierr)

     DO i=1,dim_buf
        buf(i) = myrank*dim_buf+i-1;
     END DO

     ! Open the file and write 
     ... call MPI_File_open to access "output.dat" file in writing mode

     ... call MPI_File_write_ordered to write onto the file

     ... call MPI_File_close to free the file

     ! Re-open the file and read data
     ... call MPI_File_open to access "output.dat" file in reading mode

     ... call MPI_File_read_ordered to read from the file

     ... call MPI_File_close to free the file
     
     WRITE(*,*) "myid ",myrank," buffer after read:"
     WRITE(*,*) buf

     CALL MPI_Finalize(ierr)

END PROGRAM mpi2io