#!/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").
# (Long version; no 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

# Make sure they are files, not directories.
#
if [ ! -f "$1" ]; then
	echo 1>&2 "$0: '$1' is not a file"
	exit 1
fi
if [ ! -f "$2" ]; then
	echo 1>&2 "$0: '$2' is not a file"
	exit 1
fi

# Make sure they are readable.
#
if [ ! -r "$1" ]; then
	echo 1>&2 "$0: '$1' is not a readable file"
	exit 1
fi
if [ ! -r "$2" ]; then
	echo 1>&2 "$0: '$2' is not a readable file"
	exit 1
fi

# Make sure they are not executable.
#
if [ -x "$1" ]; then
	echo 1>&2 "$0: '$1' is executable"
	exit 1
fi
if [ -x "$2" ]; then
	echo 1>&2 "$0: '$2' is executable"
	exit 1
fi

# Make sure they aren't empty.
#
if [ ! -s "$1" ]; then
	echo 1>&2 "$0: '$1' is empty"
	exit 1
fi
if [ ! -s "$2" ]; then
	echo 1>&2 "$0: '$2' is empty"
	exit 1
fi

# 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