diffy

#!/bin/bash -e

FILE1=""
FILE2=""
ARGS="-t"
MAXWIDTH=""

# check arguments
while [ $# -gt 0 ]; do
	case $1 in
	-M)
		MAXWIDTH=$2
		shift; shift
	;;
	-L)
		ARGS="$ARGS --left-column"
		shift
	;;
	-t)
		ARGS=$(echo "$ARGS" | sed 's/-t\b//')
		shift
	;;
	-*)
		ARGS="$ARGS $1"
		shift
	;;
	*)
		if [ -n "$FILE2" ]; then
			echo "Unexpected extra argument $1"
			exit 1
		elif [ -n "$FILE1" ]; then
			FILE2="$1"
		else
			FILE1="$1"
		fi
		shift
	;;
	esac
done

if [ -z "$FILE1" ] || [ -z "$FILE2" ]; then
	echo "Must specify two files"
	exit 1
fi

# find max length of lines in files, pad it a little
len1=$(wc -L < "$FILE1")
len2=$(wc -L < "$FILE2")
len=$(( $len1 > $len2 ? $len1 : $len2 ))
len=$(( $len*2 + 10 ))
if [ -n "$MAXWIDTH" ]; then
	len=$(( $len > $MAXWIDTH ? $MAXWIDTH : $len ))
fi

diff -y --width $len $ARGS "$FILE1" "$FILE2" | less -S