#!/bin/sh -u
#  $0  file1 file2
# Compare two non-empty files for identical content.
# Display the number of lines of differences (as output by "diff").
# (Short version; uses a loop.)
# -IAN!  idallen@ncf.ca

export PATH=/bin:/usr/bin
umask 022

if [ $# -ne 2 ]; then
	echo 1>&2 "$0: Expecting 2 arguments; found $# ($*)"
	exit 1
fi

for file do
	# Make sure they are files, not directories.
	# Make sure they are readable.
	# Make sure they are not executable.
	# Make sure they aren't empty.
	#
	if [ ! -f "$file" ]; then
		echo 1>&2 "$0: '$file' is not a file"
		exit 1
	fi
	if [ ! -r "$file" ]; then
		echo 1>&2 "$0: '$file' is not a readable file"
		exit 1
	fi
	if [ -x "$file" ]; then
		echo 1>&2 "$0: '$file' is executable"
		exit 1
	fi
	if [ ! -s "$file" ]; then
		echo 1>&2 "$0: '$file' is empty"
		exit 1
	fi
done

# Count the differences.
# Display the count if not zero.
#
diffs=$(diff "$1" "$2" | wc -l)
if [ "$diffs" -ne 0 ]; then
	echo "$0: File '$1' and file '$2' are different."
	echo "$0: Number of lines of differences: $diffs"
fi