#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

# Compare two directories, listing files that exist only in the first and not
# the second.
#
# Useful for quickly comparing two directories for missing files. From
# https://stackoverflow.com/questions/28205735/how-do-i-compare-file-names-in-two-directories-in-shell-script

[[ $# != 2 ]] && echo "Usage: ${0##*/} dir1 dir2" && exit 1
dir1=$1
dir2=$2

find "$dir2" "$dir2" "$dir1" -printf '%P\n' | sort | uniq -u