Write a shell script that will add two nos, which are supplied as command line argument, and if this two nos are not given show error and its usage

#
# write shell script that will add two nos, which are supplied as command line argument, and if this two nos are not given show error and its usage
#

if [ $# -ne 2 ]
then
    echo "Usage - $0   x    y"
    echo "       SUM of Where x and y is#"
    exit 1
fi
    echo "Sum of $1 and $2 is `expr $1 + $2`"