--- ioctl(cmd[, arg])

    IO Фƥƥॳ ioctl ¹Ԥη̤֤ޤ
    ǽξܺ٤ ioctl(2) [manual page] 򻲾ȤƤ

    arg λˤϤͤʸξˤ 
    pack ¤ΤȤߤʤioctl Ϥޤ
    arg ά줿Ȥ䡢nil, false ΤȤ 0
    true ФƤ 1  ioctl Ϥޤ

