Guess The Random Number Game

Time to practice your Bash script and develop a simple game.

Exercise

Create a bash script that implements a number guessing game. The script should:

1. Generate a random number between 1 and 100
2. Allow the user to make guesses
3. Provide feedback whether the guess is too high, too low, or correct
4. Count the number of attempts
5. Allow the user to play again after winning

The game should continue until the user guesses correctly, and then ask if they want to play another round.

💡 Hints

• Use $RANDOM to generate random numbers
• The modulo operator % can help limit the range
• Use a while loop for the main game logic
• Consider using a nested loop structure for replay functionality
• Input validation is important - check if the user enters a valid number

Test data

Test Case 1: Basic game flow

$ ./guessing_game.sh
Welcome to the Number Guessing Game!
I'm thinking of a number between 1 and 100.

Enter your guess: 50
Too low! Try again.
Enter your guess: 75
Too high! Try again.
Enter your guess: 62
Too low! Try again.
Enter your guess: 68
Congratulations! You guessed it in 4 attempts!

Do you want to play again? (yes/no): no
Thanks for playing! Goodbye!

Test Case 2: Input validation

$ ./guessing_game.sh
Welcome to the Number Guessing Game!
I'm thinking of a number between 1 and 100.

Enter your guess: abc
Invalid input! Please enter a number between 1 and 100.
Enter your guess: 150
Your guess must be between 1 and 100!
Enter your guess: 0
Your guess must be between 1 and 100!
Enter your guess: 42
Too high! Try again.

Test Case 3: Multiple rounds

$ ./guessing_game.sh
Welcome to the Number Guessing Game!
I'm thinking of a number between 1 and 100.

Enter your guess: 30
Congratulations! You guessed it in 1 attempts!

Do you want to play again? (yes/no): yes

Starting new game...
I'm thinking of a number between 1 and 100.

Enter your guess: 50
Too low! Try again.
Enter your guess: 60
Congratulations! You guessed it in 2 attempts!

Do you want to play again? (yes/no): no
Thanks for playing! Goodbye!

Solution 1: Basic implementaion

This is a straightforward implementation using nested while loops. The outer loop controls whether the player wants to play again, while the inner loop handles the guessing game logic. Key features:

• Uses $RANDOM % 100 + 1 to generate numbers between 1-100
• Input validation with regex pattern matching
• Simple counter for tracking attempts

#!/bin/bash

# Number Guessing Game - Basic Implementation

# Main game loop
play_again="yes"

echo "Welcome to the Number Guessing Game!"

while [[ "$play_again" == "yes" ]]; do
    # Generate random number between 1 and 100
    secret_number=$((RANDOM % 100 + 1))
    attempts=0
    guessed=false
    
    echo "I'm thinking of a number between 1 and 100."
    echo
    
    # Game loop for current round
    while [[ "$guessed" == "false" ]]; do
        # Read user input
        echo -n "Enter your guess: "
        read guess
        
        # Validate input - check if it's a number
        if ! [[ "$guess" =~ ^[0-9]+$ ]]; then
            echo "Invalid input! Please enter a number between 1 and 100."
            continue
        fi
        
        # Check if guess is in valid range
        if [[ $guess -lt 1 || $guess -gt 100 ]]; then
            echo "Your guess must be between 1 and 100!"
            continue
        fi
        
        # Increment attempt counter
        ((attempts++))
        
        # Check the guess
        if [[ $guess -eq $secret_number ]]; then
            echo "Congratulations! You guessed it in $attempts attempts!"
            guessed=true
        elif [[ $guess -lt $secret_number ]]; then
            echo "Too low! Try again."
        else
            echo "Too high! Try again."
        fi
    done
    
    # Ask if player wants to play again
    echo
    echo -n "Do you want to play again? (yes/no): "
    read play_again
    play_again=$(echo "$play_again" | tr '[:upper:]' '[:lower:]')
    
    if [[ "$play_again" == "yes" ]]; then
        echo
        echo "Starting new game..."
    fi
done

echo "Thanks for playing! Goodbye!"

Solution 2: Using functions

In this solution, I break down the game into modular functions, making the code more organized and reusable:

• generate_random(): Generates the secret number
• validate_input(): Handles all input validation
• play_round(): Contains the core game logic
• ask_replay(): Manages the replay prompt
• main(): Orchestrates the overall game flow

#!/bin/bash

# Number Guessing Game - Function-based Implementation

# Function to generate random number
generate_random() {
    echo $((RANDOM % 100 + 1))
}

# Function to validate input
validate_input() {
    local input=$1
    
    # Check if input is a number
    if ! [[ "$input" =~ ^[0-9]+$ ]]; then
        echo "Invalid input! Please enter a number between 1 and 100."
        return 1
    fi
    
    # Check if number is in range
    if [[ $input -lt 1 || $input -gt 100 ]]; then
        echo "Your guess must be between 1 and 100!"
        return 1
    fi
    
    return 0
}

# Function to play one round
play_round() {
    local secret_number=$(generate_random)
    local attempts=0
    local guess
    
    echo "I'm thinking of a number between 1 and 100."
    echo
    
    while true; do
        # Get user input
        echo -n "Enter your guess: "
        read guess
        
        # Validate input
        if ! validate_input "$guess"; then
            continue
        fi
        
        # Increment attempts
        ((attempts++))
        
        # Check guess
        if [[ $guess -eq $secret_number ]]; then
            echo "Congratulations! You guessed it in $attempts attempts!"
            break
        elif [[ $guess -lt $secret_number ]]; then
            echo "Too low! Try again."
        else
            echo "Too high! Try again."
        fi
    done
}

# Function to ask for replay
ask_replay() {
    local response
    echo
    echo -n "Do you want to play again? (yes/no): "
    read response
    response=$(echo "$response" | tr '[:upper:]' '[:lower:]')
    
    [[ "$response" == "yes" ]]
}

# Main program
main() {
    echo "Welcome to the Number Guessing Game!"
    
    while true; do
        play_round
        
        if ! ask_replay; then
            break
        fi
        
        echo
        echo "Starting new game..."
    done
    
    echo "Thanks for playing! Goodbye!"
}

# Run the main program
main

Solution 3: Enhanced version with difficulty levels

I added a few extra features:

• Difficulty levels with different number ranges
• Performance feedback based on attempts
• Hints when guesses are very far off
• Better user experience with clear menu options

#!/bin/bash

# Number Guessing Game - Enhanced Version with Difficulty Levels

# Function to display menu
show_menu() {
    echo "Select difficulty level:"
    echo "1. Easy (1-50)"
    echo "2. Medium (1-100)"
    echo "3. Hard (1-200)"
    echo -n "Enter your choice (1-3): "
}

# Function to get range based on difficulty
get_range() {
    case $1 in
        1) echo 50 ;;
        2) echo 100 ;;
        3) echo 200 ;;
        *) echo 100 ;;  # Default to medium
    esac
}

# Main game
echo "Welcome to the Number Guessing Game!"
echo

play_again="yes"

while [[ "$play_again" == "yes" ]]; do
    # Select difficulty
    show_menu
    read difficulty
    
    # Validate difficulty selection
    if ! [[ "$difficulty" =~ ^[1-3]$ ]]; then
        echo "Invalid choice! Using medium difficulty."
        difficulty=2
    fi
    
    # Get range for selected difficulty
    max_number=$(get_range $difficulty)
    
    # Generate random number
    secret_number=$((RANDOM % max_number + 1))
    attempts=0
    
    echo
    echo "I'm thinking of a number between 1 and $max_number."
    echo
    
    # Game loop
    while true; do
        echo -n "Enter your guess: "
        read guess
        
        # Validate input
        if ! [[ "$guess" =~ ^[0-9]+$ ]]; then
            echo "Invalid input! Please enter a number."
            continue
        fi
        
        if [[ $guess -lt 1 || $guess -gt $max_number ]]; then
            echo "Your guess must be between 1 and $max_number!"
            continue
        fi
        
        ((attempts++))
        
        # Check guess
        if [[ $guess -eq $secret_number ]]; then
            echo "Congratulations! You guessed it in $attempts attempts!"
            
            # Give performance feedback
            if [[ $attempts -le 5 ]]; then
                echo "Excellent! You're a mind reader!"
            elif [[ $attempts -le 10 ]]; then
                echo "Good job! That was quick!"
            else
                echo "Well done! Practice makes perfect!"
            fi
            break
        elif [[ $guess -lt $secret_number ]]; then
            echo "Too low! Try again."
            # Give hint for very far guesses
            if [[ $((secret_number - guess)) -gt $((max_number / 4)) ]]; then
                echo "(Hint: You're quite far off!)"
            fi
        else
            echo "Too high! Try again."
            # Give hint for very far guesses
            if [[ $((guess - secret_number)) -gt $((max_number / 4)) ]]; then
                echo "(Hint: You're quite far off!)"
            fi
        fi
    done
    
    # Ask for replay
    echo
    echo -n "Do you want to play again? (yes/no): "
    read play_again
    play_again=$(echo "$play_again" | tr '[:upper:]' '[:lower:]')
    
    if [[ "$play_again" == "yes" ]]; then
        echo
        echo "Starting new game..."
        echo
    fi
done

echo "Thanks for playing! Goodbye!"

📖 Concepts to revise

The solutions discussed here use some terms, commands and concepts and if you are not familiar with them, you should learn more about them.

• Variables: secret_number, attempts, guess
• Arithmetic operations: $RANDOM % 100 + 1, numeric comparisons
• Conditional statements: if/elif/else for guess validation and checking
• Loops: while loops, nested loops, continue statement
• Regular expressions: [[ "$guess" =~ ^[0-9]+$ ]] for number validation
• Functions: Modular code organization (Solutions 2 & 3)
• Input/Output: read command, echo with -n flag
• String manipulation: tr command for case conversion
• Command substitution: $(command) syntax

📚 Further reading

If you are new to bash scripting, we have a streamlined tutorial series on Bash that you can use to learn it from scratch or use it to brush up the basics of bash shell scripting.

Bash Scripting Tutorial Series for Beginners [Free]

Get started with Bash Shell script learning with practical examples. Also test your learning with practice exercises.

Linux HandbookAbhishek Prakash