In this section, we will cover the basics of creating and running a Bash script. This is a fundamental skill for anyone looking to automate tasks or perform complex operations in a Unix-like environment.

A Bash script is a plain text file containing a series of commands that are executed by the Bash shell. Scripts can automate repetitive tasks, manage system operations, and perform complex sequences of commands.

1. Open a Text Editor: You can use any text editor like nano, vim, or gedit. For simplicity, we'll use nano in this example.

   nano my_script.sh
   

2. Write Your Script: Start by writing a simple script. The first line should be the shebang (#!) followed by the path to the Bash interpreter.

   #!/bin/bash
   echo "Hello, World!"
   

3. Save and Exit: Save the file and exit the text editor. In nano, you can do this by pressing CTRL + X, then Y, and Enter.

Before you can run your script, you need to make it executable. Use the chmod command to change the file permissions.

You can run your script by specifying its path. If the script is in the current directory, use ./ followed by the script name.

Let's break down the example script:

• #!/bin/bash: This is the shebang line. It tells the system to use the Bash interpreter to execute the script.
• echo "Hello, World!": This command prints "Hello, World!" to the terminal.

Exercise 1: Create and Run a Simple Script

1. Open a text editor and create a new file named greet.sh.
2. Write a script that prints "Welcome to Bash Scripting!".
3. Save the file and exit the text editor.
4. Make the script executable.
5. Run the script.

Solution:

1. Open a text editor:

   nano greet.sh
   

2. Write the script:

   #!/bin/bash
   echo "Welcome to Bash Scripting!"
   

3. Save and exit:

   • Press CTRL + X, then Y, and Enter.

4. Make the script executable:

   chmod +x greet.sh
   

5. Run the script:

   ./greet.sh
   

• Forgetting the Shebang: Without the shebang, the system may not know which interpreter to use.
• File Permissions: Ensure the script is executable. Use chmod +x scriptname.sh.
• Path Issues: If the script is not in your PATH, you need to specify the relative or absolute path to run it.

In this section, you learned how to create and run a simple Bash script. You now know how to:

• Create a script file using a text editor.
• Write a basic script with a shebang and a simple command.
• Make the script executable.
• Run the script from the command line.

Next, we will dive into variables and constants, which will allow you to create more dynamic and powerful scripts.