[luci] attempt to index global 'io' (a nil value)

[子文]

Dear all
   I add the following code(marked with red color)  in the file /model/network.lua,  why  it always have the error ( attempt to index global 'io' (a nil value) ?
function get_wifinet(self, net)
    local wnet = _wifi_lookup(net)
    local file = io.open('//tmp//sunbin11.txt', "r")
    file:close()   
    if wnet then
        return wifinet(wnet)
    end
end
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.subsignal.org/pipermail/luci/attachments/20160329/a303e728/attachment.html>