#!/bin/bash

# Test command line arguments

if [ $# != 2 ]; then
        echo "usage: $0 [file1] [file2]"
        exit 1
fi

FILE1=$1
FILE2=$2
TMPF="$FILE1.tmp"

echo "Checking files..."
if [ ! -f "$FILE1" ]; then
	echo "error: $FILE1 does not exist!"
	exit 1
fi

if [ ! -f "$FILE2" ]; then
        echo "error: $FILE2 does not exist!"
        exit 1
fi

if [ -f "$TMPF" ]; then
        echo "error: $TMPF already exists!"
        exit 1
fi

echo "Copying $FILE1 to $TMPF..."
cp "$FILE1" "$TMPF"

if [ ! -f "$TMPF" ]; then
        echo "Failed to create temporary file $TMPF"
        exit 1
fi

echo "Copying $FILE2 to $FILE1..."
cp "$FILE2" "$FILE1"

echo "Copying $TMPF to $FILE2..."
cp "$TMPF" "$FILE2"

echo "Deleting $TMPF..."
rm "$TMPF"