#!/bin/bash

echo "Please enter your name:"
read name
echo "Hello, $name! Welcome to the script."

#!/bin/bash

echo "Enter first number:"
read num1
echo "Enter second number:"
read num2

sum=$((num1 + num2))
difference=$((num1 - num2))
product=$((num1 * num2))
if [ $num2 -ne 0 ]; then
    quotient=$((num1 / num2))
else
    quotient="undefined (division by zero)"
fi

echo "Sum: $sum"
echo "Difference: $difference"
echo "Product: $product"
echo "Quotient: $quotient"

#!/bin/bash

echo "Enter the filename to check:"
read filename

if [ -e "$filename" ]; then
    echo "The file '$filename' exists."
else
    echo "The file '$filename' does not exist."
fi

#!/bin/bash

for i in {1..10}; do
    echo "Number: $i"
done

#!/bin/bash

echo "Enter the source directory to backup:"
read source
echo "Enter the destination directory:"
read destination

if [ -d "$source" ]; then
    cp -r "$source" "$destination"
    echo "Backup of '$source' completed in '$destination'."
else
    echo "The source directory '$source' does not exist."
fi

#!/bin/bash

usage=$(du -sh ~ | cut -f1)
limit="1G"

if [[ "$usage" > "$limit" ]]; then
    echo "Warning: Your home directory is using $usage, which exceeds the limit of $limit."
else
    echo "Your home directory usage is $usage, within the limit of $limit."
fi

#!/bin/bash

while true; do
    echo "Please enter a number between 1 and 10:"
    read number
    if [[ "$number" -ge 1 && "$number" -le 10 ]]; then
        echo "Thank you! You entered a valid number: $number"
        break
    else
        echo "Invalid number. Please try again."
    fi
done

#!/bin/bash

echo "Enter the number of seconds for the countdown:"
read seconds

for (( i=$seconds; i>=0; i-- )); do
    echo "$i"
    sleep 1
done

echo "Time's up!"

#!/bin/bash

for file in *.txt; do
    mv "$file" "${file%.txt}.bak"
done

#!/bin/bash

echo "Hostname: $(hostname)"
echo "Current user: $(whoami)"
echo "Current date and time: $(date)"

#!/bin/bash

echo "Enter the string to replace:"
read search
echo "Enter the replacement string:"
read replace

for file in *.txt; do
    sed -i "s/$search/$replace/g" "$file"
done

#!/bin/bash

echo "Enter the desired password length:"
read length

password=$(tr -dc 'A-Za-z0-9' < /dev/urandom | head -c "$length")
echo "Generated password: $password"

#!/bin/bash

echo "Enter the log file to monitor:"
read logfile

if [ -e "$logfile" ]; then
    tail -f "$logfile"
else
    echo "The file '$logfile' does not exist."
fi

#!/bin/bash

echo "Enter the directory to check:"
read directory
echo "Enter the size limit (e.g., 100M):"
read limit

size=$(du -sh "$directory" | cut -f1)

if [[ "$size" > "$limit" ]]; then
    echo "Alert: The size of '$directory' is $size, which exceeds the limit of $limit."
else
    echo "The size of '$directory' is $size, within the limit of $limit."
fi

#!/bin/bash

echo "System uptime: $(uptime -p)"

#!/bin/bash

ping -c 1 google.com &> /dev/null

if [ $? -eq 0 ]; then
    echo "Internet connection is active."
else
    echo "No internet connection."
fi

#!/bin/bash

echo "Enter the project name:"
read project

mkdir -p "$project"/{src,bin,docs}

echo "Directory structure for '$project' created."

#!/bin/bash

threshold=80

cpu_usage=$(mpstat 1 1 | awk '/Average/ {print 100 - $12}')

if (( ${cpu_usage%.*} > threshold )); then
    echo "Warning: CPU usage is at $cpu_usage%, which exceeds the threshold of $threshold%."
else
    echo "CPU usage is at $cpu_usage%, within the threshold of $threshold%."
fi

#!/bin/bash

dpkg -l

#!/bin/bash

echo "Enter the directory to check:"
read directory
echo "Enter the size limit (e.g., 100M):"
read limit
echo "Enter the email address to send the alert to:"
read email

size=$(du -sh "$directory" | cut -f1)

if [[ "$size" > "$limit" ]]; then
    echo "Alert: The size of '$directory' is $size, which exceeds the limit of $limit." | mail -s "Directory Size Alert" "$email"
else
    echo "The size of '$directory' is $size, within the limit of $limit."
fi