gpio_pwr_btn.sh

#! /bin/sh

# When you're not using systemd on your Raspberry Pi, you
# can still enjoy GPIO push-button shutdown.
# Run this as:
#   gpio_pwr_btn.sh &
# It will sit in the background and wait for GPIO to go low.
# When it does, it will issue the shutdown command.

GPIO=GPIO26
SHUTDOWN_CMD=halt

PATH=/usr/bin:/bin:/sbin

PULLED_UP_STATE=$(gpioget --bias pull-up --numeric $GPIO)
if [ $PULLED_UP_STATE -ne 1 ]; then
  echo "GPIO state is: $PULLED_UP_STATE. Expecting 1."
  echo "Is something else using $GPIO?"
  echo "Can't configure as shutdown button."
else
  gpiomon --utc --bias pull-up --edges falling --num-events 1 --quiet $GPIO
  # Will pause here until GPIO goes low.
  if [ $? -ne 0 ]; then
    echo "There was an error monitoring $GPIO. Aborting."
    exit 1
  fi
  echo "GPIO shutdown request: $GPIO" | wall
  $SHUTDOWN_CMD
fi