Local variables (local keyword) in Bash Scripting - Mini Project: Build & Apply

Using Local Variables with the local Keyword in Bash

📖 Scenario: You are writing a bash script to calculate the total price of items in a shopping list. You want to keep your calculations clean and avoid changing variables outside your function.

🎯 Goal: Build a bash script that uses a function with a local variable to calculate the total price of items without affecting variables outside the function.

📋 What You'll Learn

Create a bash array called prices with the values 10, 20, and 30

Create a function called calculate_total that uses a local variable total

Use a for loop inside the function to sum the prices

Call the function and print the total price outside the function

💡 Why This Matters

🌍 Real World

Using local variables in bash functions helps keep scripts clean and avoids accidental changes to important data outside functions.

💼 Career

Many automation and DevOps tasks use bash scripts where local variables prevent bugs and make code easier to maintain.

1

Create the prices array

Create a bash array called prices with the values 10, 20, and 30.

Bash Scripting

# Create the prices array
# Your code here

Need a hint?

Use parentheses to create a bash array: prices=(10 20 30).

2

Create the calculate_total function with a local variable

Create a function called calculate_total that declares a local variable named total and sets it to 0.

Bash Scripting

prices=(10 20 30)

# Create the calculate_total function with a local variable
# Your code here

Need a hint?

Define the function with calculate_total() { ... } and inside it write local total=0.

3

Sum the prices inside the function using a for loop

Inside the calculate_total function, use a for loop with variable price to iterate over ${prices[@]} and add each price to the local total variable.

Bash Scripting

prices=(10 20 30)

calculate_total() {
    local total=0
    # Use a for loop to sum prices
    # Your code here
}

Need a hint?

Use for price in "${prices[@]}"; do ... done and update total inside the loop.

4

Call the function and print the total

Call the calculate_total function, then print the value of total outside the function using echo. Note: Since total is local, declare a global total variable before calling the function and update it inside the function by returning the value.

Bash Scripting

prices=(10 20 30)

total=0
calculate_total() {
    local total=0
    for price in "${prices[@]}"; do
        total=$((total + price))
    done
    # Return the total value
    # Your code here
}

# Call the function and print the total
# Your code here

Need a hint?

Use echo "$total" inside the function to output the sum, then capture it with total=$(calculate_total) and print it with echo "$total".