cronjob to update packages (uses checkupdates)

crontab

# /etc/crontab: configuration file for cron

# See cron(8) and crontab(5) for details.

# m h dom mon dow user command
0 * * * * root /root/idlenice /root/fetch-updates
@reboot root /root/idlenice /root/fetch-updates

fetch-updates

#!/bin/bash
pidof -sq pacman || { ping example.com -qw2 -c1 && checkupdates -d; }

idlenice

#!/bin/sh
nice -n 19 ionice -c 2 -n 7 "$@"