Bash MultipleScreen Random Wallpaper

#!/bin/bash

shopt -s nullglob

cd /root/Documents/wallpaper



files=()
for i in *.jpg *.png; do
    [[ -f $i ]] && files+=("$i")
done
range=${#files[@]}
echo ${#files[@]}

while true; do

    number=$RANDOM
    let "number %= $range"
    SCREEN1="/root/wallpaper/${files[number]}"
    number=$RANDOM
    let "number %= $range"
    SCREEN2="/root/wallpaper/${files[number]}"
    number=$RANDOM
    let "number %= $range"
    SCREEN3="/root/wallpaper/${files[number]}"

    imlibsetroot -x 0 -s f "${SCREEN1}" -x 1 -s f "${SCREEN2}" -x 2 -s f "${SCREEN3}" 2>/dev/null
	sleep 10s
done