Bash Program to Check Whether the Given String is a Palindrome or Not

Given a string str, find whether the given string is palindrome or not using Bash Scripting. A string is called a palindrome string if the reverse of the string is the same as the original string.

Examples:

Input: str= “GFG”

Output: GFG is a palindrome string.

Explanation: Reverse of “GFG” is “GFG”, hence it is palindrome.

Input: bash

Output: bash is not a palindrome string.

Explanation: Reverse of “bash” is “hsab”, hence it is not palindrome.

Shell Script to Check Whether the Given String is a Palindrome or Not

#!/bin/bash

read -p “Enter a string: ” input_string

# Reverse the string and compare with the original

if [[ “$input_string” == “$(rev <<< “$input_string”)” ]]; then
echo “The entered string ‘$input_string’ is a palindrome.”
else
echo “The entered string ‘$input_string’ is not a palindrome.”
fi

Save the above script in a file, for example, example.sh. Make it executable by running:

chmod +x example.sh

You can then execute the script:

./example.sh

Explanation:

1. `read -p "Enter a string: " input_string`: This line prompts the user to enter a string and stores their input in the variable `input_string`.
2. `if [[ "$input_string" == "$(rev <<< "$input_string")" ]]; then`: This line starts an if statement. It checks if the entered string is equal to its reverse. Here’s how it works:
   • `"$(rev <<< "$input_string")"`: This part uses the `rev` command to reverse the entered string. The `<<<` is a “here-string” that provides the string as input to rev.
   • `"${input_string}" == "$(rev <<< "$input_string")"`: This compares the original string with its reversed version.
   • If the comparison is true, the script executes the commands inside the `then` block.
3. echo "The entered string '$input_string' is a palindrome.": If the entered string is a palindrome (i.e., it reads the same backward as forward), this line prints a message indicating that the string is a palindrome.
4. else: If the comparison in the `if` statement is false, meaning the string is not a palindrome, the script moves to the `else` block.
5. echo "The entered string '$input_string' is not a palindrome.": This line prints a message indicating that the string is not a palindrome.

Time Complexity: O(n) , Auxiliary Space: O(n)