#!/usr/bin/env bash

# Start in the script's pwd
#  (ideally something like /usr/share/wallpapers/thurstylark/)
wallp_dir=$(dirname "$0")

# Get one subdir from $wallp_dir
wallp_subdir=$(find "$wallp_dir" -type d | shuf -n 1)

# Get one file from $wallp_subdir
find $wallp_subdir -type f \( -iname \*.jpg -o -iname \*.png \) | shuf -n 1