Your Unix machine is awaited in Valhalla - witness!

README.md

The shutdown messages on the Mac/Linux command line are baked into the /sbin/shutdown executable.

This replaces the messages with suitable Mad Max: Fury Road quotes. You can make your own, but since you're patching a binary file the replacements MUST, I repeat MUST be exactly the same number of characters as the original, or your computer will not ride eternal, shiny and chrome.

The two versions below are for a Ubuntu Linux variant, and Mac OS X Yosemite (both versions Work For Me on at least one machine).

valhalla-shutdown-mac-yosemite.sh

LANG=C sudo sed -i '' 's/The system is going down for reboot/I live, I die, I live again! Reboot/g' /sbin/shutdown
LANG=C sudo sed -i '' 's/The system is going down for power off in/I am awaited in Valhalla! Powering off in/g' /sbin/shutdown
LANG=C sudo sed -i '' 's/The system is going down for halt in/I am awaited in Valhalla! Halting in/g' /sbin/shutdown
LANG=C sudo sed -i '' 's/The system is going down for maintenance/Mediocre!  Shutting down for maintenance/g' /sbin/shutdown
LANG=C sudo sed -i '' 's/The system is going down for/WITNESS ME! System going for/g' /sbin/shutdown

valhalla-shutdown-ubuntu.sh

sudo sed -i 's/The system is going down for reboot/I live, I die, I live again! Reboot/g' /sbin/shutdown
sudo sed -i 's/The system is going down for power off in/I am awaited in Valhalla! Powering off in/g' /sbin/shutdown
sudo sed -i 's/The system is going down for halt in/I am awaited in Valhalla! Halting in/g' /sbin/shutdown
sudo sed -i 's/The system is going down for maintenance/Mediocre!  Shutting down for maintenance/g' /sbin/shutdown
sudo sed -i 's/The system is going down for/WITNESS ME! System going for/g' /sbin/shutdown