Bash Scripting Lecture Notes

Introduction

• Bash scripting is essential for anyone looking to become a hacker, cloud engineer, or IT professional.
• Learning bash scripting enables faster automation of tasks such as hacking networks or creating virtual machines (VMs).
• Bash is a valuable skill for employability.

Episode 1 Overview

• Introduction to bash scripting series.
• Objective: From basic understanding to creating complex scripts.

What is Bash?

• Bash stands for Bourne Again Shell.
• Created as an improvement over the original shell from the 1970s, developed in 1989.
• Bash is the command line in Linux; it interfaces with the Linux OS.
• Functions as a powerful programming/scripting language.

Starting Bash Scripting

• Linux Environment: Essential for practicing bash scripting.
  • Use Linode (cloud service) for quick Linux deployment.
  • Offers $100 credit for new users, costs about 1 penny per hour.
  • Can use WSL2 on Windows or existing Linux installations as alternatives.
• Setting Up Linode: Create a Linux VM using Ubuntu 20.04.
  • Use SSH to connect.

First Bash Script: "Hi Mom"

• Command Line Basics: Inside the bash shell.
  • Check current shell with which $SHELL.

Writing the Script

• Use nano as a text editor: nano hi_mom.sh
• Script Content: #!/bin/bash echo "Hi Mom"
• Exiting Nano:
  • Ctrl + X, then Y to save, Enter to confirm the filename.

Running the Script

• Execute Script: bash hi_mom.sh
• Automating: Add sleep commands and more echo statements to simulate conversation.
  • Example:
  echo "Hi Mom" sleep 3 echo "Oh wow" sleep 3 echo "Can't believe that" echo "Bye, love you too"

Permissions and Executables

• Run Scripts Without bash Prefix: ./hi_mom.sh
  • Initial attempt may fail due to permission denied error.
• Change Permissions: Use chmod +x hi_mom.sh to make the script executable.
• Verify Permissions: ls -l shows permissions.

Further Improvements

• Running with New Permissions: ./hi_mom.sh should now run.

Conclusion

• Bash scripts automate command line tasks.
• Future series episodes will delve deeper into bash scripting.
• Encourage engagement with YouTube channel (likes, comments, subscribes).

Additional Notes

• Remember to delete the VM after usage to avoid charges.
• Continual learning: next episodes will build on this foundation.