I'm having a lot of trouble getting a shutdown button to work, whether it's with adding dtoverlay=gpio-shutdown to config.txt or with your script.
Upon running sudo /etc/init.d/listen-for-shutdown.sh start I get:
RuntimeWarning: A physical pull up resistor is fitted on this channel!
I'd really like to get this button working but the extent of my raspberry pi knowledge is following tutorials and I can't seem to figure out what's wrong so I don't corrupt another SD card.