Shell Script to check if a string is palindrome or not

Program

#!/bin/bash
echo "Enter a String"
read input
reverse=""
len=${#input}
for (( i=$len-1; i>=0; i-- ))
do 
	reverse="$reverse${input:$i:1}"
done
if [ $input == $reverse ]
then
    echo "$input is palindrome"
else
    echo "$input is not palindrome"
fi

Output 1

Enter a String
test
test is not palindrome

Output 2

Enter a String
malayalam
malayalam is palindrome