Running Linux on your router and wifi devices is fantastic, but it’s important to keep them up-to-date. This is how I auto-update my devices with the latest packages from OpenWrt (but not firmware, I still do that manually when there’s a new release).

This is a very simple shell script which uses OpenWrt’s package manager to fetch a list of updates, and then install them, rebooting the machine if that was successful. The log file is served up over http, in case you want to get the log easily to see what’s been happening (assuming you’re running uhttpd service).

Make a directory to hold the script.
root@firewall:~# mkdir -p /usr/local/sbin

Make the script.
root@firewall:~# cat > /usr/local/sbin/update-system.sh << \EOF
#!/bin/ash
opkg update
# upgrade netifd first as it causes drop out and system upgrade fails
opkg upgrade netifd
# install luci-ssl, so we get web back after upgrades
opkg install luci-ssl
/etc/init.d/uhttpd restart
# do package upgrades
PACKAGES="$(opkg list-upgradable |awk '{print $1}')"
if [ -n "${PACKAGES}" ]; then
  opkg upgrade ${PACKAGES}
  if [ "$?" -eq 0 ]; then
    echo "$(date -I"seconds") - update success, rebooting" \
>> /www/update.result
    exec reboot
  else
    echo "$(date -I"seconds") - update failed" >> /www/update.result
  fi
else
  echo "$(date -I"seconds") - nothing to update" >> /www/update.result
fi
EOF


Make the script executable and touch the log file.
root@firewall:~# chmod u+x /usr/local/sbin/update-system.sh
root@firewall:~# touch /www/update.result

Make sure the script and results are kept when upgrading the firmware.
root@firewall:~# echo "/usr/local/sbin/" >> /etc/sysupgrade.conf
root@firewall:~# echo "/www/update.result" >> /etc/sysupgrade.conf

Next schedule the script in cron.
root@firewall:~# crontab -e

My cron entry looks like this, to run at 2am every day.

0 2 * * * /usr/local/sbin/update-system.sh

Now just start and enable cron.
root@firewall:~# /etc/init.d/cron start
root@firewall:~# /etc/init.d/cron enable

Give it a run manually, if you want.
root@firewall:~# /usr/local/sbin/update-system.sh

Download a copy of the log from another machine (once the router has finished rebooting).
chris@box:~$ curl http://router/update.result
2018-03-18T10:14:49+1100 - nothing to update

That’s it! Now if you have multiple devices you can do the same, but maybe just set the cron entry for a different time of the night.