--- sysseek(offset[, whence])     ruby 1.7 feature

    lseek(2) [manual page] ƱǤseek Ǥϡ
    sysread, syswrite ʻѤưʤ
    ˤΥ᥽åɤȤޤХåե󥰤줿 IO Ф
    ¹Ԥ㳰 IOError ȯޤ

     IO#seek [IO/seek] ƱǤ

    offset ֤ؤΰưаư(եƬ
    ΰ)֤ޤư˼Ԥ㳰 Errno::EXXX ȯ
    ޤ

