--- IO.readlines(path[, rs])

    path ǻꤵ줿եɤ߹ǡγƹԤǤ
    Ƥ֤ޤ
    IO  EOF ãƤж [] ֤ޤ

    礦ɰʲΤ褦Ư򤷤ޤ

      port = open(path)
      begin
        port.readlines
      ensure
        port.close
      end

    Ԥζڤϰ rs ǻꤷʸˤʤޤrs 
    ǥեͤȤ߹ѿ $/ ͤǤ

    rs  nil ꤹȹԶڤʤȤߤʤޤ
    ʸ "" ꤹϢ³ԤԤζڤȤߤʤޤ
    (ѥ饰ե⡼)

    path Υץ󡢥եɤ߹ߤ˼Ԥ㳰 
    Errno::EXXX ȯޤ

