1.)write  a shell script that displays a digital clock and a calendar side by side in the terminal. It updates every second.

#!/bin/bash

# Function to display digital clock and calendar side by side

show_clock_calendar() 
{
    while true; do
        clear  # Clears the screen for real-time updates

        # Get current time and date
        TIME=$(date +"%H:%M:%S")  
        DATE=$(date +"%A, %d %B %Y")

        # Get current month's calendar
        CALENDAR=$(cal)

        # Display Digital Clock & Calendar side by side
        echo "=============================================="
        echo "       DIGITAL CLOCK               CALENDAR   "
        echo "=============================================="
        echo ""
        printf "   Time: %s            %s\n" "$TIME" "$(date +"%B %Y")"
        printf "   Date: %s\n\n" "$DATE"

        # Print calendar in a formatted way
        paste <(echo "$CALENDAR") <(printf "\n\n\n\n\n")  

        echo ""
        echo "=============================================="

        sleep 1  # Refresh every second
    done
}

# Call the function
show_clock_calendar



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2).Write a  shell script that uses a switch-case (case statement) to let the user:

1️⃣ Check if a file exists
2️⃣ Check if a directory exists
3️⃣ Check if a file is empty

#!/bin/bash

# Function to check if a file exists
check_file() 
{
    echo "Enter the file name:"
    read filename
    if [ -f "$filename" ]; then
        echo "File '$filename' exists."
    else
        echo "File '$filename' does not exist."
    fi
}

# Function to check if a directory exists
check_directory() {
    echo "Enter the directory name:"
    read dirname
    if [ -d "$dirname" ]; then
        echo "Directory '$dirname' exists."
    else
        echo "Directory '$dirname' does not exist."
    fi
}

# Function to check if a file is empty
check_empty_file() {
    echo "Enter the file name:"
    read filename
    if [ -f "$filename" ]; then
        if [ ! -s "$filename" ]; then
            echo "File '$filename' is empty."
        else
            echo "File '$filename' is not empty."
        fi
    else
        echo "File '$filename' does not exist."
    fi
}

# Main menu using case statement
echo "Choose an option:"
echo "1. Check if a file exists"
echo "2. Check if a directory exists"
echo "3. Check if a file is empty"
echo "4. Exit"
read choice

case $choice in
    1) check_file ;;
    2) check_directory ;;
    3) check_empty_file ;;
    4) echo "Exiting..."; exit ;;
    *) echo "Invalid option. Please enter a valid choice." ;;
esac
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3).write a shell script that takes a list of numbers as input from the user and sorts them in ascending order using the Bubble Sort method.

#!/bin/bash

# Function to perform Bubble Sort
bubble_sort() {
    local -n arr=$1  # Use a nameref to modify the original array
    local n=${#arr[@]}  # Get the number of elements in array

    for ((i = 0; i < n-1; i++)); do
        for ((j = 0; j < n-i-1; j++)); do
            if (( arr[j] > arr[j+1] )); then
                # Swap arr[j] and arr[j+1]
                temp=${arr[j]}
                arr[j]=${arr[j+1]}
                arr[j+1]=$temp
            fi
        done
    done
}

# Read numbers from user
echo "Enter numbers separated by space: "
read -a numbers  # Read input as an array

# Call bubble sort function
bubble_sort numbers

# Display sorted numbers
echo "Sorted numbers in ascending order: ${numbers[@]}"

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4).write a shell script that lets the user enter a number and checks whether it's an Armstrong number using a function.

#!/bin/bash

# Function to check if a number is Armstrong
is_armstrong() {
    local num=$1
    local sum=0
    local digit
    local temp=$num

    # Get number of digits
    local n=${#num}

    # Calculate sum of digits raised to the power of n
    while [ $temp -gt 0 ]; do
        digit=$((temp % 10))
        sum=$((sum + digit ** n))
        temp=$((temp / 10))
    done

    # Check if the number is Armstrong
    if [ $sum -eq $num ]; then
        echo "$num is an Armstrong number."
    else
        echo "$num is NOT an Armstrong number."
    fi
}

# Main Script
echo "Enter a number:"
read number

# Validate input
if ! [[ "$number" =~ ^[0-9]+$ ]]; then
    echo "Invalid input. Please enter a positive integer."
    exit 1
fi

# Call the function
is_armstrong "$number"