Turn on router LED from cronjob

Installing and Using OpenWrt
1

Hello people,

tl;dr version:

How can I turn LED lights on/off from a cronjob? Or, is there a better way of turning a LED based on a command output?

Long version:

I recently installed OpenWRT on a tp-link Archer C7 router and it's working great!
I have configured it to use PIA vpn provider with OpenVPN. Anyone interested I did a quick script for setting up and enable specific configs

I have also configured the router's WPS button to turn on/off the OpenVPN service as a quick way to turn the VPN on/off.

One thing that I haven't been able to do yet, is to make the LEDs work the way I want.

I would like to have the router's WPS LED to be ON when OpenVPN is running and OFF when it's not.

But I couldn't yet make it work with a cronjob. Maybe I'm missing something regarding how cronjobs work? Not sure.

Here's the cronjob I'm trying:

* * * * * echo "$([ $(pgrep -f openvpn) ] && echo default-on || echo none)" > /sys/class/leds/tp-link\:green\:wps/trigger

Manually running the command has the desired effect, but nothing happens with the cronjob.
Nothing very useful from the logs (from my understanding at least) either.

Ultimately, I want the light to be on/off according to the output of a command. I'm going for a cronjob as this is what I can think of. Happy to try another way if there's any.

Another thing that came to my mind is some sort of hook for OpenVPN, like: OpenVPN starts, turn light on. OpenVPN stops, turn ligh off. But I have not found such a thing yet.

Any ideas where to go from here?

2

master

commit 8fe9940db66517679f09fa1d2f6f79229b6a8361
openvpn: add generic hotplug mechanism

otherwise try and hook into something else in hotplug / procd trigger / inotifywatch /tmp/vpn.status or lookup 'pservice' ...

or even simpler... use the up / down scripts...

1 Like
3

There are differences between cron and interactive shells; one of them is that PATH is not set in a cron shell. One way to debug cron commands is by using ( command ) 2>&1 >>/root/cron.log and then looking at the logs in the file.

5

Presumably this should work.

6

You mean something like this?

That's still an open issue unfortunately.

Or you mean something else?

7

Thanks for the tip, but no luck with that. The file /root/cron.log is created but it's empty.

8

I went through it before but didn't realize I could use tun0 dev in this option.

Thanks a lot, it works now!

For reference, this is the config I'm using:

# /etc/config/system

config led 'led_wps'     
        option name 'WPS'               
        option dev 'tun0'       
        option mode 'link'     
        option sysfs 'tp-link:green:wps'
        option trigger 'netdev'
9

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