wscat returns nothing when launced from a cron @reboot

[JulienDevillers]

Hello,

I want to notify the reboot of a raspberry pi to another server using wscat.
I wrote this script:

#!/bin/sh

date >> reboot.log
cmd="wscat -n -x reboot -c  wss://xxxxxxxxxxxxxxxx.com:18800/sub"

OUTPUT=$($cmd)

echo $OUTPUT
while [ $OUTPUT != "ok" ]; do
  	sleep 30
	OUTPUT=$($cmd)
done

--> it works well from command line with and without sudo. The server returns "ok" and the script stops before entering the loop.

-->When launched from this cronjob :
@reboot /home/pi/xxxxxxxx/rebootNotify.sh
Nothing is returned from the wscat command, the script enters infinitly the loop (The loop exists in case
unavailable network at reboot time. BTW, adding a sleep in the cron before calling the scripts leads to the same
result).
Where is the bug?

note : wscat has been installed using sudo npm install -g wscat.

Thanks
Julien

[lpinca]

I don't know, if the script works when run manually it should also work when run as a cron job. Check if the server receives the message. If you don't control it use another one.

Also check the crontab PATH. It is possible that wscat is not found.

[JulienDevillers]

Thanks for your answer.
I'm sure that server receives nothing and even not a connection attempt.

I echoed the path variable in the script.
Called from my own session, path is
/usr/local/sbin:/usr/local/bin/:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games:/snap/bin
Called from crontab:
/usr/local/sbin:/usr/local/bin/:/usr/sbin:/usr/bin:/sbin:/bin
I don't see any significative difference.

I also added "which wscat" command that returns in both case the correct path...

[s-wust]

I can confirm this behaviour.
Run from bash
/usr/local/bin/wscat -x . -c wss://example.com > /tmp/output.txt
writes the output to output.txt as expected while run from cron
*/1 * * * * /usr/local/bin/wscat -x . -c wss://example.com > /tmp/output.txt
only creates an empty file