#!/bin/bash

# Download and compare text from two URLs in parallel
# License: LGPLv2
# Author:
#    http://www.pixelbeat.org/

# Be careful to quote URLs appropriately like:
#  urldiff 'URL1' 'URL2'

# Follow redirections and only show errors as generally
# text for comparison is relatively small
curl --version &>/dev/null && URLGET="curl -sS -L" || URLGET="wget -nv -O-"

# Download in parallel and compare
idiff <($URLGET "$1") <($URLGET "$2")

# Note it would be better to avoid diffing if one of the URLGETs fail,
# though that would involve manipulating named pipes directly,
# so KISS and rely on error messages and only addition of lines,
# to indicate (partial) errors.