Same as my last gist but probably what more people want. Renames custom pictures correctly.

rename2.sh

# Just move the images.
# Usage: bash rename2.sh "playlistfile.lpl" "/retroarch/thumbnails/folder"
IFS=$'\n'
for file in $(cat "$1" | grep -oP '.*"path":.*/\K.*\.([^"]*)'); do
	ext=${file##*.}
	escfile=$(echo $file | perl -pe 's/([[\]()+\$^{}])/\\$1/g')
	newname=$(cat "$1" | grep -zoP "(/|\\\)$escfile"'",\s*\"label\": \"\K[^"]*')
	newname=$(echo "$newname" | perl -pe 's/[&*\/:`<>?\|]/_/g')
	dir="${1:0:-4}"
	if [[ "${file:0:-((${#ext}+1))}" != "$newname" ]]; then
		if [ -f "$2/$dir/Named_Snaps/$newname.png" ]; then
			echo "Good."
		else
			mv -v "$2/$dir/Named_Boxarts/${file:0:-((${#ext}+1))}.png" "$2/$dir/Named_Boxarts/$newname.png"
			mv -v "$2/$dir/Named_Titles/${file:0:-((${#ext}+1))}.png" "$2/$dir/Named_Titles/$newname.png"
			mv -v "$2/$dir/Named_Snaps/${file:0:-((${#ext}+1))}.png" "$2/$dir/Named_Snaps/$newname.png"
		fi
	fi
done
unset IFS