Debugging Pi

Cron

Scripts run by cron (crontab) do not inherit environment variables.

Filtering Cron jobs from syslog

grep -i CRON /var/log/syslog

Common error

Nov 29 06:00:01 farmpi CRON[17531]: (pi) CMD (/home/pi/getSensorData.sh) Nov 29 06:00:01 farmpi CRON[17530]: (CRON) info (No MTA installed, discarding output)

In this instance there is no message interface so no errors were logged. option 1 - install postfix sudo apt-get install postfix If you select local installation, the output from your cron jobs will be relayed to a local “mailbox” that you can easily tail: sudo tail -f /var/mail/ option 2 - Add email to crontab MAILTO="" MAILTO="mymail.com" **NOTE:** Never attempted mail. This is tbd notes for later.

Reloading cron

/etc/init.d/cron reload sudo service cron restart

env -i /home/pi/

bsh for cron SHELL=/bin/bash

list cron crontab -l

/etc/cron.allow /etc/cron.deny

basics

• needs to be executable (chmod +x)
• will not have environment variables (test w/ env -i)
• every 5 minutes */5 * * * * /home/pi/getSensorData.sh

Services

debugging systemctl services

sudo systemctl enable kasaMqtt sudo systemctl start kasaMqtt sudo systemctl daemon-reload sudo systemctl service –status-all systemctl list-units –type service –all

sudo systemctl status kasaMqtt.service farmpi.service farmclock.service journalctl -u kasaMqtt.service | tail -n 300

see errors

journalctl -p 0 0: emergency 1: alerts 2: critical 3: errors 4: warning 5: notice 6: info 7: debug

#list reboots journalctl –list-boots

debugging systemctl services

sudo systemctl enable kasaMqtt sudo systemctl start kasaMqtt sudo systemctl daemon-reload sudo systemctl service –status-all systemctl list-units –type service –all

see errors

journalctl -p 0 0: emergency 1: alerts 2: critical 3: errors 4: warning 5: notice 6: info 7: debug

#list reboots journalctl –list-boots

journalctl -u kasaMqtt.service

Shutting down the Pi

sudo shutdown -h now