Shell Script To Concatenate Two String Given as Input including its length

#!/bin/bash
# Write a shell program to concatenate to two String given as input and display the
# resultant string along with its string length.
# --------------------------------------------------------------------
# This is a free shell script under GNU GPL version 2.0 or above
# Copyright (C) 2005 nixCraft project.
# Feedback/comment/suggestions : http://cyberciti.biz/fb/
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
 
STR1=$1
STR1=$2
OUT="$1$2"
if [ $# -eq 0 ]
then
	echo "$0 string1 string2"
	exit 1
fi
 
len=$(expr length $OUT)
 
echo "Concatenate string is - $OUT"
echo "String Length is - $len"