wallpaperd version of lunifybg by Xyne: https://bbs.archlinux.org/viewtopic.php?id=155540

lunifybg-wpd

#!/bin/sh

if [[ -d "$XDG_CACHE_HOME" ]]
then
	mkdir -p "$XDG_CACHE_HOME"
fi
cd -- "$XDG_CACHE_HOME"

# Use a subdirectory to save images of the moon. It's interesting to cycle
# through them with feh to see it move.
mkdir -pv luna

function display_help()
{
	echo "usage: $0 <refresh|show|clear|help>"
	echo "	refresh - download current image of the moon"
	echo "	show - create composite background with last image of the moon"
	echo "	clear - reset the background"
	echo "options: edit the script to change composition parameters"
	echo "				 see http://www.imagemagick.org/Usage/compose/ for help"
	echo "dependencies: wallpaperd, sed, grep, imagemagick, wget"
}

if [[ -z $1 ]]
then
	display_help
	exit 1
fi

if [[ -f ~/.wallpaperd.cfg ]]
then
	if [[ ! -f ~/.config/wallpaperd/orig ]]
	then
		mkdir -vp ~/.config/wallpaperd
		mv -v ~/.wallpaperd.cfg ~/.config/wallpaperd/orig
	fi
	if [[ $1 == refresh ]];then
		cp -v ~/.config/wallpaperd/{orig,lunarized}
	fi
else
	echo "~/.wallpaperd.cfg does not exist"
	exit 1
fi

function clear_wallpaperd() {
	rm -v ~/.wallpaperd.cfg
	cp -vf ~/.config/wallpaperd/orig ~/.wallpaperd.cfg
}

function update_wallpaperd() {
	searchpath="$(grep 'path\.search' ~/.config/wallpaperd/orig|cut -d= -f2-)"
	wallpapers=$(grep 'wallpaper\.[^\.]*\.image' ~/.config/wallpaperd/orig)

	moon_img=$(pre_refresh)
	if ! $(echo "$searchpath" | grep "$XDG_CACHE_HOME/luna");then
		sed -e "s@$searchpath@${searchpath}:$XDG_CACHE_HOME/luna@g" -i ~/.config/wallpaperd/lunarized
	fi

	grep '^wallpaper\.[^\.]*\.image' ~/.config/wallpaperd/lunarized|while read line;do
		place="$(echo "$line"|cut -d. -f2)"
		bg_img="$(echo "$line"|cut -d. -f3-|cut -d= -f2)"
		for i in $(echo $searchpath | tr ":" "\n")
		do
			echo "${i/\~/$HOME}/$bg_img exists?"
			if [[ -e "${i/\~/$HOME}/$bg_img" ]]
			then
				echo "Found $bg_img in $i, now lunarizing"
				update_wallpaper "$place" "${i/\~/$HOME}" "$bg_img" "$moon_img"
				break
			fi
		done
	done
	rm -v ~/.wallpaperd.cfg
	cp -vf ~/.config/wallpaperd/lunarized ~/.wallpaperd.cfg
}

function update_wallpaper()
{
	# Path to the composite image.
	comp_img=luna/"bg-desktop-${1}.jpg"
	# The original background image.
	bg_img="$2/$3"
	# Update the command to use the composite image and avoid overwriting ~/.fehbg.
	refresh "$bg_img" "$4" "$comp_img" "${5:-northeast}"
	sed -e "s@^wallpaper.${1}.image=${3}@wallpaper.${1}.image=bg-desktop-${1}.jpg@g" \
		-i ~/.config/wallpaperd/lunarized
}

# Create new bg image with current image of moon.
function pre_refresh()
{
	moon_img="luna/moon-$(date +'%Y.%m.%d.%H.%M.%S.png')"
	wget -O "$moon_img" 'http://api.usno.navy.mil/imagery/moon.png'
	echo "$moon_img"
}

function refresh()
{
	bg_img="$1"
	moon_img="$2"
	comp_img="$3"
	placement="${4:-northeast}"
	convert -trim "$moon_img" - | \
	composite -compose Screen -gravity $placement - "$bg_img" "$comp_img"
}


while [[ ! -z $1 ]]
do
	case "$1" in
		refresh)
			update_wallpaperd
		;;

		show)
			wallpaperd -s
			wallpaperd
		;;

		clear)
			clear_wallpaperd
		;;

		-h | --help | help)
			display_help
			exit 0
		;;

		*)
			display_help
			exit 1
		;;
	esac
	shift
done