--- IO.sysopen(path[, mode [, perm]])   ruby 1.7 feature

    pathǻꤵե򥪡ץ󤷡ե뵭һҤ֤
    եΥץ˼Ԥ㳰 Errno::EXXX ȯ
    ޤ

     mode, perm ˤĤƤ Ȥ߹ߴؿ 
    open ƱǤ

    IO.for_fd ʤɤ IO ֥Ȥˤʤ¤ꡢΥ᥽
    ɤǥץ󤷤ե򥯥ʤϤޤ

