demo_process_writeline Program

    program demo_process_writeline
    use, intrinsic :: iso_fortran_env, only : &
       & stdin=>input_unit, &
       & stdout=>output_unit, &
       & stderr=>error_unit
    use m_process ,only: process_open_write, process_writeline
    use m_process ,only: streampointer, process_close
    implicit none
    type(streampointer) :: fp
    ! line of data to write
    character(len=4096) :: line
    integer             :: ierr
    integer             :: i
      ! open process to write to
      call process_open_write('cat -n',fp,ierr)
      write(*,*)'WRITETEST: process is opened with status ',ierr
      ! remember C and Fortran I/O are often independent of each other
      flush(stdout)
      ierr=0
      line='xxxxxxxxxxxxxxxxxxxxxxxxxxx'
      do i=1,10
        ! write a line to the process
        call process_writeline(trim(line),fp,ierr)
        if(ierr.lt.0)then
          write(*,*)'WRITETEST: ierr is ',ierr
          exit
        endif
      enddo
      call process_close(fp,ierr)
      write(*,*)'WRITETEST: process closed with status ',ierr
    end program demo_process_writeline