twi.vim

    let ps = vimproc#popen3('path/to/t_sample')

    call ps.stdin.write('write_test!')
    call ps.stdin.close() 

" close無しだと以下のreadで空
    let output = ps.stdout.read()
    echomsg " 2 stdout echos " . output

    " finish
    call ps.stdout.close()
    call ps.stderr.close()
    call ps.waitpid()