Update packages from crontab

Do not try this at home!

Warning: Doing automatic updates from cron is strongly discouraged. It is likely to leave your machine in a broken and unbootable state. If this breaks your machine, do not hold anyone but yourself responsible. You have been warned.

So, proceed only if you have balls of steel or you were intending to crash your machine anyway. If so, you might as well do it the "right way".

1. First, you (obviously!) need to install cron itself. Do that first.
2. It is highly recommended to also install a mail transfer agent, such as Postfix, to send you notifications if pacman fails.
3. Run as root: crontab -e
4. Copy-paste this to your crontab:

MAILTO=your@email
LOGFILE=/var/log/cron-pacman.log

# 1. minute (0-59)
# |   2. hour (0-23)
# |   |   3. day of month (1-31)
# |   |   |   4. month (1-12)
# |   |   |   |   5. day of week (0-7: 0 or 7 is Sun, or use names)
# |   |   |   |   |   6. commandline
# |   |   |   |   |   |
#min hr  dom mon dow command
00   13   *   *   *  . /etc/profile && (echo; date; yes |pacman -Syuq) &>>$LOGFILE || (echo 'pacman failed!'; tail $LOGFILE; false)

If you want to automatically reboot your computer upon a successful upgrade, append '&& reboot' to the above line.

Do try this at home!

Instead of using `pacman -Syuq` above, use `pacman -Syuwq`. The '-w' will cause pacman to "retrieve all packages from the server, but do not install/upgrade anything." While you will still have to manually update your system, you won't have to wait (as long) for packages to download while doing so.