diffi - Better diff output script

diffi.sh

#!/bin/bash

# diffi - Better diff output script
# BeanBagKing - https://gist.github.com/BeanBagKing

# If both arguments aren't given, print help text
if [ -z $1 ] || [ -z $2 ]; then
    echo "Usage: `basename $0` [OLD] [NEW]"
    exit 1
fi

# Gather Arguments
OLD=$1
NEW=$2

# Define variable to printf esc sequence, so it works on macOS/other non-GNU sed
# http://unix.stackexchange.com/questions/45924/using-sed-to-color-the-output-from-a-command-on-solaris/45954 
esc=$(printf '\033')

# Put everything together
diff -u $OLD $NEW | sed -n '1,2d;/^[-+]/p' | sed -e "s/^-/${esc}[31m-${esc}[0m/" | sed -e "s/^+/${esc}[32m+${esc}[0m/"