Automatic screen locking via Bluetooth

autolock.sh

#!/bin/bash

# Simple script to lock your screen when your phone is out of range. Don't rely
# on this (obviously), but it can be used to provide a faster idle lock if you do
# forget to lock your screen.

# Bluetooth address of the unlock device
DEVICE=AA:BB:CC:00:00:00

# Name of the unlock device
DEVICE_NAME="Nexus 6P"

# How long before the script starts looking for the Bluetooth device (in ms)
IDLE_TIME=10000

while true; do
  if [ `xprintidle` -gt $IDLE_TIME ];
  then
    echo "Checking $DEVICE_NAME state..."
    state=`hcitool name $DEVICE`
    if [ "$state" != "$DEVICE_NAME" ]; then
      echo "Device absent, locking..."
      dbus-send --type=method_call --dest=org.gnome.ScreenSaver \
        /org/gnome/ScreenSaver org.gnome.ScreenSaver.Lock
      # After locking, we sleep for a while. This prevents you from getting
      # locked out over and over in case of a bug.
      sleep 60
    else
      # Don't check more than every five seconds
      sleep 5
    fi
  fi
  sleep 1
done