This is a small script, intended to be run from systemd, that will shutdown the Pi if it detects a state change on a GPIO pin. This would be caused by a button or switch that ties a GPIO pin either to ground or +5V.
Note: The pin is identified by the GPIO Number not the board number
The script listens for a state change on the specified pin. The states are either RISING or FALLING.
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FALLING: The button ties the pin to ground. In this case, the internal resistor will be set to PULLUP.
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RISING: The button ties the pin to +5V. In this case, the internal resister will be set to PULLDOWN.
There are hard-coded defaults in the script. In the git repository, the script has a default state of FALLING and the default pin is 21. Pin 21 is the last pin on the Pi and is next to a ground pin on the next row. It's a convinient place to attach the button.
The script can be configured in one of three ways:
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Command line args. The pin is the first arg. The state ("FALLING" or "RISING") is the second arg. If no state, or no pin or state is specified, then the values will either be the hard-coded defaults or those values that are defined as below. The command line args take precedence over the methods 2 or 3.
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Environment Variables. See `examples/systemd/
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Environment File. See `examples/default/
- Python3
- RPi.GPIO from PyPi
Place listen-for-shutdown.py somewhere from where
systemd can run it, such as /usr/local/bin.
Modify examples/systemd/listen-for-shutdown.service and place it in /etc/systemd/system
If using an environment file, modify
examples/default/listen-for-shutdown and place it where appropriate
for your OS. In Raspbian this is /etc/default/.
sudo systemctl enable listen-for-shutdown.service
sudo systemctl start listen-for-shutdown.service
sudo systemctl status listen-for-shutdown.service
If the service failed, use journalctl to investigate:
sudo journalctl -xe -u listen-for-shutdown.service