Command line: What wifi channel is actually being used?

For Developers
1

From the command line, wifi status gives lots of detail but it does not tell me which WiFI channel is actually being used when my configuration is set up for automatic channel selection.
wireless.radio0.channel='auto'

Is there a nice clean way to find it, or do I need to parse the output of
iwinfo or iwinfo $dev freqlist?

Thanks!

2

You can use what LuCI is doing internally and get that same info in nice json output. To see the list of calls,

$ ubus -v list iwinfo
'iwinfo' @d7352a59
        "devices":{}
        "info":{"device":"String"}
        "scan":{"device":"String"}
        "assoclist":{"device":"String","mac":"String"}
        "freqlist":{"device":"String"}
        "txpowerlist":{"device":"String"}
        "countrylist":{"device":"String"}
        "survey":{"device":"String"}
        "phyname":{"section":"String"}

Lets run an interesting looking one

$ ubus call iwinfo devices
{
        "devices": [
                "phy0-ap0",
                "phy1-ap0"
        ]
}

$ ubus call iwinfo info '{"device":"phy0-ap0"}'
{
        "phy": "phy0",
        "ssid": "blah",
        "bssid": "48:FF:FF:2A:FF:8F",
        "country": "US",
        "mode": "Master",
        "channel": 9,
        "center_chan1": 9,
        "frequency": 2452,
        "frequency_offset": 0,
...
5 Likes
3

Ah interesting. Very useful

1 Like
4

Do you know the jsonfilter tricks for easy use in shell scripts?

$ ubus call iwinfo info '{"device":"phy0-ap0"}' | \
  jsonfilter -e 'channel=$.channel' -e 'auth=$.encryption.authentication[*]'
export channel=9; export auth='psk'\ 'sae';

Now just eval the output and you've captured the values in shell variables:

$ eval $(ubus call iwinfo info '{"device":"phy0-ap0"}' | jsonfilter -e 'channel=$.channel' -e 'auth=$.encryption.authentication[*]')

$ echo $channel
9

$ echo $auth
psk sae
5 Likes
5

Cute eval trick. I like it and it may actually be useful.

6

But ucode is much more elegant.

$ cat iwinfo.uc
#!/usr/bin/ucode -S

import * as mod_ubus from "ubus";

let ubus = mod_ubus.connect();

let devices  = ubus.call("iwinfo", "devices");
for (let device in devices.devices) {
    let info = ubus.call("iwinfo", "info", {device: device});
    printf("%s %3d  %s\n", device, info.channel, info.bssid);
}

ubus.disconnect();

produces

$ chmod +x iwinfo.uc
$ ./iwinfo.uc
phy0-ap0   9  48:FF:FF:2A:FF:8F
phy1-ap0  40  48:FF:FF:2A:FF:90
2 Likes
7

@twinkleLED @efahl
I use:
iw dev <ifname> info

For example on a meshnode here I get:

root@meshnode-8ecb:/# iw dev m-11s-0 info
Interface m-11s-0
	ifindex 15
	wdev 0x3
	addr 96:83:c4:a2:8e:cb
	type mesh point
	wiphy 0
	channel 1 (2412 MHz), width: 40 MHz, center1: 2422 MHz
	txpower 20.00 dBm
	multicast TXQ:
		qsz-byt	qsz-pkt	flows	drops	marks	overlmt	hashcol	tx-bytes	tx-packets
		0	0	240396	0	0	0	969	21281035		240410
root@meshnode-8ecb:/#