Custom exit codes (exit N) in Bash Scripting - Mini Project: Build & Apply

Custom Exit Codes in Bash Scripts

📖 Scenario: You are writing a small bash script to check if a user is allowed to enter a club based on their age. The script will exit with different codes to show if the user is too young, just right, or too old.

🎯 Goal: Build a bash script that uses custom exit codes with exit N to indicate different age categories.

📋 What You'll Learn

Create a variable age with a specific value.

Create a variable min_age to set the minimum allowed age.

Use if statements to check the age and exit with custom codes.

Print a message showing the exit code after running the script.

💡 Why This Matters

🌍 Real World

Scripts often need to tell other programs or users what happened by using exit codes. Custom exit codes help identify specific situations like errors or special cases.

💼 Career

Understanding exit codes is important for automation, debugging, and writing scripts that work well with other tools in system administration and DevOps.

1

Set the user's age

Create a variable called age and set it to 20.

Bash Scripting

# Create a variable called age and set it to 20
# Your code here

Need a hint?

Use age=20 to assign the value.

2

Set the minimum allowed age

Create a variable called min_age and set it to 18.

Bash Scripting

age=20
# Create a variable called min_age and set it to 18
# Your code here

Need a hint?

Use min_age=18 to assign the value.

3

Use if statements to set custom exit codes

Write an if statement that checks if age is less than min_age. If yes, exit with code 1. Otherwise, if age is between min_age and 30 inclusive, exit with code 0. Else, exit with code 2.

Bash Scripting

age=20
min_age=18
# Write if statements to exit with codes 1, 0, or 2 based on age
# Your code here

Need a hint?

Use if, elif, and else with exit N commands.

4

Print the exit code after running the script

Run the script and print the exit code using echo and $?.

Bash Scripting

age=20
min_age=18
if [ "$age" -lt "$min_age" ]; then
    exit 1
elif [ "$age" -le 30 ]; then
    exit 0
else
    exit 2
fi

# Print the exit code below
# Your code here

Need a hint?

After running the script, use echo $? in the terminal to see the exit code.