19.Write a shell script to change case of string.

 #!/bin/bash

# Read input from the user

read -p "Enter a string: " input

# Prompt for case conversion choice

echo "Choose an option:"

echo "1. Convert to UPPERCASE"

echo "2. Convert to lowercase"

read -p "Enter choice (1 or 2): " choice

# Change case based on user choice

if [ "$choice" -eq 1 ]; then

    output=$(echo "$input" | tr '[:lower:]' '[:upper:]')

    echo "Converted to UPPERCASE: $output"

elif [ "$choice" -eq 2 ]; then

    output=$(echo "$input" | tr '[:upper:]' '[:lower:]')

    echo "Converted to lowercase: $output"

else

    echo "Invalid choice. Please enter 1 or 2."

    exit 1

fi