Lock screen on Linux with i3lock and Gnome 3

screenlock.sh

#!/bin/sh -e

if [ `ps -u $USER | grep -Ec "(i3lock|totem|mpv|vlc|*mplayer)"` -gt 0 ]; then
    exit
fi

i3lock -c 333333 -i ~/Pictures/Wallpapers/screenlock.png -f;

function get_idle_time() {
	gdbus call --session --dest org.gnome.Shell --object-path /org/gnome/Mutter/IdleMonitor/Core --method org.gnome.Mutter.IdleMonitor.GetIdletime | sed -r 's/.*uint64 *([0-9]+).*/\1/g';
}

monitorOff=0
idleMillisecondsLimit=5000
while true; do
	pgrep i3lock >/dev/null || exit;
	idleMilliseconds=`get_idle_time`;
	if [ "$idleMilliseconds" -ge "$idleMillisecondsLimit" ] && [ "$monitorOff" = "0" ]; then
		xset dpms force off;
		monitorOff=1;
	elif [ "$idleMilliseconds" -le "$idleMillisecondsLimit" ] && [ "$monitorOff" = "1" ] ; then
		monitorOff=0;
	fi
	sleep 1;
done