if-elif-else in Bash Scripting - Mini Project: Build & Apply

Basic Decision Making with if-elif-else in Bash

📖 Scenario: You are writing a simple script to check the temperature and give advice on what to wear.

🎯 Goal: Create a bash script that uses if-elif-else statements to print clothing advice based on the temperature.

📋 What You'll Learn

Create a variable temperature with a specific value

Create a variable cold_threshold to set the cold temperature limit

Use if-elif-else to check if temperature is below cold_threshold, between cold_threshold and 25, or above 25

Print the correct advice message for each temperature range

💡 Why This Matters

🌍 Real World

Scripts like this help automate decisions based on changing data, such as weather or system status.

💼 Career

Understanding if-elif-else is essential for writing scripts that respond to different conditions in IT, DevOps, and automation roles.

1

Set the temperature variable

Create a variable called temperature and set it to 18.

Bash Scripting

# Create a variable called temperature and set it to 18
# Your code here

Need a hint?

Use variable=value syntax without spaces for bash variables.

2

Set the cold temperature threshold

Create a variable called cold_threshold and set it to 15.

Bash Scripting

temperature=18
# Create a variable called cold_threshold and set it to 15
# Your code here

Need a hint?

Remember to use the same syntax as before for variables.

3

Write the if-elif-else decision structure

Write an if-elif-else statement that checks the value of temperature against cold_threshold and 25. Use -lt for less than and -le for less or equal in numeric comparisons. The conditions are:
1. If temperature is less than cold_threshold, print "Wear a jacket".
2. Else if temperature is less or equal to 25, print "Wear a sweater".
3. Else, print "Wear a t-shirt".

Bash Scripting

temperature=18
cold_threshold=15
# Write if-elif-else to print clothing advice based on temperature
# Your code here

Need a hint?

Use square brackets with spaces and double quotes around variables for safety.

4

Run the script and display the output

Print the output of the script by running it or echoing the result. The expected output is exactly Wear a sweater.

Bash Scripting

temperature=18
cold_threshold=15
if [ "$temperature" -lt "$cold_threshold" ]; then
    echo "Wear a jacket"
elif [ "$temperature" -le 25 ]; then
    echo "Wear a sweater"
else
    echo "Wear a t-shirt"
fi
# Run the script to show the output
# Your code here

Need a hint?

Just run the script or save and execute it to see the output.