Shifting arguments (shift) in Bash Scripting - Mini Project: Build & Apply

Shifting Arguments (shift) in Bash Scripting

📖 Scenario: You are writing a simple Bash script that processes command-line arguments one by one. This is like unpacking items from a bag, handling each item, and then moving on to the next.

🎯 Goal: Build a Bash script that uses shift to handle each argument separately and prints them in order.

📋 What You'll Learn

Create a Bash script with a list of arguments

Use a variable to count how many arguments are left

Use a while loop to process each argument

Use shift to move to the next argument

Print each argument with its position number

💡 Why This Matters

🌍 Real World

Many Bash scripts need to process command-line arguments one at a time. Using <code>shift</code> helps handle each argument cleanly, like unpacking items from a bag in order.

💼 Career

Understanding how to use <code>shift</code> is essential for writing flexible shell scripts that automate tasks, parse options, and manage inputs in system administration and DevOps roles.

1

Set up initial arguments

Create a Bash script that sets the positional parameters to exactly these three arguments: apple, banana, and cherry using set -- apple banana cherry.

Bash Scripting

# Assign the arguments apple, banana, and cherry
# Your code here

Need a hint?

Use set -- followed by the exact arguments to set the positional parameters.

2

Create a counter for arguments

Add a variable called count that stores the number of arguments using $#.

Bash Scripting

set -- apple banana cherry
# Create a variable count to hold the number of arguments
# Your code here

Need a hint?

The special variable $# holds the number of arguments.

3

Process arguments with a while loop and shift

Write a while loop that runs while count is greater than zero. Inside the loop, print the current argument number and the first argument $1. Then use shift to move to the next argument and decrease count by 1.

Bash Scripting

set -- apple banana cherry
count=$#
# Write a while loop to process arguments
# Your code here

Need a hint?

Use while [ $count -gt 0 ] to loop. Use shift to move arguments. Decrease count by 1 each time.

4

Print the final output

Run the script so it prints each argument with its position number exactly as:
Argument 1: apple
Argument 2: banana
Argument 3: cherry

Bash Scripting

set -- apple banana cherry
count=$#
total=$#
while [ $count -gt 0 ]; do
  echo "Argument $(( total - count + 1 )): $1"
  shift
  count=$((count - 1))
done
# Run the script to print the output
# Your code here

Need a hint?

Run the script and check the output matches the expected lines exactly.