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I have a Pi Zero W running Raspbian Stretch Lite (June 2018). I'm using it to turn the crank on an automatic cat feeder. I've barely changed the base configuration: apt-get-installed git and samba, used Python's pip to install wiringpi and psutil, and scheduled my Python script to run at 7AM and 7PM using crontab -e.

In the mornings I've been finding the pi shut down and missed the 7AM feeding. Unplug/replug brings it back up. I set up a ping test from my desktop and discovered for the last three days that the system shuts down at exactly 11:23 in the evening (eastern daylight time).

I've confirmed that there is no cron job for the pi user or the super user for that time (or at any time, other than the feedings.) I'm pretty new to Linux. What could be causing this?

Update 2:

I stayed up tonight and observed the issue. Sure enough, the LED switched off at 11:23 and my SSH session went dead. Interesting twist: I powered it up again right away, and it shut down again about 1 minute later! This pattern repeated until around 11:28, after which point it has stayed up no problem.

Here is a gist with the /var/log/messages for the whole affair. What's strange is that the system appears to boot up at 11:17, although I didn't shut it down and my ping test didn't report an outage.

https://gist.github.com/buzzcola/6ea029d7d496d8852b4c7a062945937b

James Orr
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1 Answers1

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Solved! It turns out there's another cron file I didn't know about, /etc/crontab. I took a look and found this:

# m h dom mon dow user  command
17 *    * * *   root    cd / && run-parts --report /etc/cron.hourly
25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6    * * 7   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6    1 * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
23 3    * * *   pi      python /share/squeakernet/squeakernet.py feed
#

The last line was me, I guess. 03:23 (11pm my local time) must have been an incorrect adding of four hours instead of subtracting. When the script runs as the "pi" user (not root) it apparently causes a completely un-logged crash.

James Orr
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