Shebang line (#!/bin/bash) in Bash Scripting - Mini Project: Build & Apply

Using the Shebang Line in Bash Scripts

📖 Scenario: You want to create a simple bash script that prints a greeting message. To make sure your script runs correctly on any Linux system, you need to add a special first line called the shebang line.This line tells the system which program to use to run your script.

🎯 Goal: Build a bash script that starts with the shebang line #!/bin/bash and prints the message Hello, world!.

📋 What You'll Learn

Create a bash script file

Add the shebang line #!/bin/bash as the first line

Write a command to print Hello, world!

Run the script to see the output

💡 Why This Matters

🌍 Real World

Scripts with a shebang line run correctly on Linux systems without needing to type the interpreter manually.

💼 Career

Knowing how to write and run bash scripts with a shebang line is essential for system administrators and developers automating tasks.

1

Create the bash script file with the shebang line

Create a file named greet.sh and write the first line exactly as #!/bin/bash to specify the bash shell.

Bash Scripting

#!/bin/bash
# Your code here

Need a hint?

The shebang line must be the very first line in your script.

2

Add a greeting message command

Below the shebang line, add a command to print the text Hello, world! using echo.

Bash Scripting

#!/bin/bash
# Add an echo command to print Hello, world!
# Your code here

Need a hint?

Use echo "Hello, world!" to print the message.

3

Make the script executable

Use the command chmod +x greet.sh in the terminal to make the script executable. (This step is for your understanding; no code to write here.)

Bash Scripting

#!/bin/bash
echo "Hello, world!"
# No code to write here, just run chmod +x greet.sh in terminal

Need a hint?

Making the script executable allows you to run it directly.

4

Run the script and see the output

Run the script by typing ./greet.sh in the terminal and observe the output.

Bash Scripting

#!/bin/bash
echo "Hello, world!"
# Run the script in terminal with ./greet.sh

Need a hint?

The output should exactly be Hello, world!