root@uplink:~# cat /tmp/iwinfo-json.lua
#!/usr/bin/lua

local iw = require "iwinfo"
local dev = arg[1] or "wlan0"

function write_json(x)
        if x == nil then
                io.write("null")
        elseif type(x) == "table" then
                local k, v
                if type(next(x)) == "number" then
                        io.write("[ ")
                        for k, v in ipairs(x) do
                                write_json(v)
                                if next(x, k) then
                                        io.write(", ")
                                end
                        end
                        io.write(" ]")
                else
                        io.write("{ ")
                        for k, v in pairs(x) do
                        io.write(string.format("%q: ", k))
                                write_json(v)
                                if next(x, k) then
                                        io.write(", ")
                                end
                        end
                        io.write(" }")
                end
        elseif type(x) == "number" or type(x) == "boolean" then
                if (x ~= x) then
                        -- NaN is the only value that doesn't equal to itself.
                        io.write("Number.NaN")
                else
                        io.write(tostring(x))
                end
        else
                io.write(string.format('"%s"', tostring(x):gsub('["%z\1-\31]', function(c)
                        return '\u%04x' % c:byte(1)
                end)))
        end
end


local backend = iw.type(dev)
if not backend then
	error("No such wireless device:", dev)
end

local info = { }
local _, field

for _, field in ipairs({
	"ssid", "bssid", "mode", "channel", "frequency",
	"txpower", "quality", "quality_max",
	"signal", "noise", "bitrate", "encryption",
	"hwmodelist", "assoclist"
}) do
	info[field] = iw[backend][field](dev)
end

write_json(info)

root@uplink:~# lua /tmp/iwinfo-json.lua wlan1
{ "quality_max": 70, "ssid": "Funkueberwachungswagen 5", "encryption": { "enabled": true, "auth_algs": [ "OPEN" ], "description": "WPA2 PSK (CCMP)", "wep": false, "auth_suites": [ "PSK" ], "wpa": 2, "pair_ciphers": [ "CCMP" ], "group_ciphers": [ "CCMP" ] }, "assoclist": { "00:15:61:10:51:DF": { "rx_short_gi": true, "noise": -95, "rx_mcs": 5, "tx_40mhz": true, "rx_40mhz": true, "tx_rate": 108000, "tx_packets": 739361, "tx_short_gi": false, "rx_packets": 402970, "tx_mcs": 11, "inactive": 2060, "rx_rate": 120000, "signal": -75 } }, "bssid": "C0:3F:0E:7A:A0:96", "hwmodelist": { "a": true, "n": true, "g": false, "b": false }, "bitrate": 108000, "txpower": 17, "noise": -95, "channel": 149, "signal": -75, "mode": "Master", "quality": 35, "frequency": 5745 }
root@uplink:~#