#!/bin/sh
#/ Usage: intersect <file1> <file2>
#/
#/ Report lines that appear in both files.
#/
# Iain Murray, April 2011

set -e

# Usage message:
[ "$#" -eq 2 ] || {
    grep '^#/' <"$0" | cut -c4-
    exit 1
}

( sort -u "$1" ; sort -u "$2" ) | sort | uniq -d