arch-desktop/install/usr/local/bin/wallpaper

#!/bin/bash

# set sane defaults
[ -z "$wallpaper_sleep_for" ] && wallpaper_sleep_for="180"
[ -z "$wallpaper_path" ] && wallpaper_path="$(xdg-user-dir PICTURES)/wallpaper"
mkdir -p "$wallpaper_path"

# validate wallpaper path
[ $(find "$wallpaper_path" -type f | wc -l) -gt 0 ] || exit 1

# there can be only one
while [ $(ps aux | grep -v 'grep' | grep -c "$0") -gt 2 ]; do
	kill $(ps aux | grep -v 'grep' | grep -v $$ | grep "$0" | awk '{print $2}') &> /dev/null
done

# infinitely change wallpaper
while true; do
	sway_outputs=( $(swaymsg -t get_outputs | jq -r '.[].name') )
	for op in "${sway_outputs[@]}"; do
		wp="$(find $wallpaper_path -type f | sort -R | tail -1)"
		swaymsg "output $op bg $wp" fit \#001E27
	done
	sleep $wallpaper_sleep_for
done