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Auto-run script when Wifi card is plugged in (udev) [Resolved]

I've been trying to use udev to make a Debian system run a bash script when a wireless card is connected.

So far I created this file /etc/udev/rules.d/wifi-detect.rules:

ACTION=="add", ATTRS{idVendor}=="0cf3", ATTRS{idProduct}=="9271", RUN+="/root/test.sh"

And for now, I'm trying to make test.sh with this contents work:

#!/bin/bash
/bin/echo "test!" > /test.txt

But for some reason, nothing seems to happen when I connect the wireless card, no test.txt file is created.

My lsusb on the card:

Bus 001 Device 015: ID 0cf3:9271 Atheros Communications, Inc. AR9271 802.11n

Running udevadm monitor –env this is what happens when I connect the card:

KERNEL[1017.642278] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3 (usb)
KERNEL[1017.644676] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0 (usb)
KERNEL[1017.645035] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/firmware/1-1.3 (firmware)
KERNEL[1017.708056] remove   /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/firmware/1-1.3 (firmware)
UDEV  [1017.714772] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3 (usb)
UDEV  [1017.733002] remove   /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/firmware/1-1.3 (firmware)
UDEV  [1017.772669] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/firmware/1-1.3 (firmware)
UDEV  [1017.798707] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0 (usb)
KERNEL[1018.456804] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/ieee80211/phy8 (ieee80211)
KERNEL[1018.465994] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/net/wlan0 (net)
KERNEL[1018.479878] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/leds/ath9k_htc-phy8 (leds)
KERNEL[1018.483074] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/usb_device/usbdev1.20 (usb_device)
UDEV  [1018.600456] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/leds/ath9k_htc-phy8 (leds)
UDEV  [1018.604376] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/ieee80211/phy8 (ieee80211)
UDEV  [1018.626243] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/usb_device/usbdev1.20 (usb_device)
KERNEL[1018.659318] move     /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/net/wlan1 (net)
UDEV  [1018.758843] add      /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/net/wlan1 (net)
UDEV  [1018.932207] move     /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/net/wlan1 (net)

I've tried a lot of examples around but I can't make it work. I hope someone can help me out with this one ;) Thank you!


EDIT:

To simplify thing, I changed my rule to:

ACTION=="add", ATTRS{idVendor}=="0cf3", ATTRS{idProduct}=="9271", RUN+="/bin/echo 'test' > /test.txt"

I managed to set udevadm control --log-priority=info as @user1146332 suggested and I got this interesting log:

Sep  9 16:27:53 iklive-rpi1 udevd[1537]: RUN '/bin/echo 'test' > /test.txt' /etc/udev/rules.d/wifi-detect.rules:1
Sep  9 16:27:53 iklive-rpi1 udevd[1544]: starting 'firmware.agent'
Sep  9 16:27:53 iklive-rpi1 udevd[126]: seq 663 queued, 'remove' 'firmware'
Sep  9 16:27:53 iklive-rpi1 udevd[126]: seq 663 forked new worker [1547]
Sep  9 16:27:53 iklive-rpi1 udevd[1537]: 'firmware.agent' [1544] exit with return code 0
Sep  9 16:27:53 iklive-rpi1 udevd[1548]: starting '/bin/echo 'test' > /test.txt'
Sep  9 16:27:53 iklive-rpi1 udevd[1547]: seq 663 running
Sep  9 16:27:53 iklive-rpi1 udevd[1547]: no db file to read /run/udev/data/+firmware:1-1.3.4: No such file or directory
Sep  9 16:27:53 iklive-rpi1 udevd[1547]: passed -1 bytes to netlink monitor 0x1af5ee0
Sep  9 16:27:53 iklive-rpi1 udevd[126]: seq 663 done with 0
Sep  9 16:27:53 iklive-rpi1 udevd[1547]: seq 663 processed with 0
Sep  9 16:27:53 iklive-rpi1 udevd[1537]: '/bin/echo 'test' > /test.txt'(out) 'test > /test.txt'
Sep  9 16:27:53 iklive-rpi1 udevd[1537]: '/bin/echo 'test' > /test.txt' [1548] exit with return code 0

So... Isn't the return code 0 the exit code for successful completion? If so why I don't get any file on the system?


EDIT 2:

I managed to get this working using the tip by @htor. My current rule:

ACTION=="add", ATTRS{idVendor}=="0cf3", ATTRS{idProduct}=="9271", RUN+="/bin/sh -c '/bin/echo test >> /test.txt'"

But by some reason the command is executed like 8 times, is there a way to avoid this? I think is is happening because when the wireless card drivers are being load they need to virtually unmount and mount the card. Tips?


Question Credit: TCB13
Question Reference
Asked July 18, 2019
Posted Under: Unix Linux
9 views
2 Answers

I had a similiar problem a while ago and the solution was to change the RUN+= part to RUN+="sh -c '/root/test.sh'". Now, I don't know if you need that in this case as the rule is calling a script, not a command.

Another observation: try removing the ! from the "test!" string or replace the double-quotes with single quotes. The bang ! is probably making trouble because of its special meaning in the shell and the double quotes preserves that meaning.


credit: Community
Answered July 18, 2019

My advise would be to set the logging priority of udev from err to info with

 udevadm control --log-priority=info

If you would like to see even more information set it to debug. Now you can find very detailed information of what udev did in /var/log/daemon.log (At least on a debian related system). Generally that helps a lot chasing errors.

This is only a complement to htor's answer which probably solve your problem.


credit: user1146332
Answered July 18, 2019
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