Shell Scripting Tutorial Notes

Introduction

• Presenter: Abhishek
• Topic: Shell Scripting from Zero to Hero
• Focus on basics, role in DevOps, and simple examples.

What is Shell Scripting?

• Shell scripting is a way to automate tasks on Linux systems.
• Reduces manual effort in repetitive tasks.
• Useful for DevOps engineers in day-to-day activities like automation, file handling, and system management.

Importance of Automation

• Automation helps reduce manual activities in any field, including software and daily tasks.
• Example: Writing numbers from 1 to 10 manually versus automating it when the range increases.

Basic Commands in Shell Scripting

1. echo: Prints text to the terminal.
2. touch: Creates new files.
3. ls: Lists files and directories in a directory.
4. man: Displays the manual or help for commands.
5. chmod: Changes file permissions:
   • 777: Read, write, and execute for everyone.
   • 444: Read permissions only.
6. cat: Displays the content of files.
7. pwd: Prints the current working directory.
8. mkdir: Creates a new directory.
9. cd: Changes the directory.
10. rm -rf: Deletes files/directories.

Writing a Shell Script

• Start with a shebang (#!/bin/bash) to specify the script's interpreter.
• Use proper indentation and comments for readability.
• Example script to create files and directories: #!/bin/bash mkdir Abhishek cd Abhishek touch first_file second_file
• Save the file using :wq in vi or vim editor.

Executing a Shell Script

• Use sh script.sh or ./script.sh to run a shell script.
• Grant execute permission with chmod before running the script.

Role of Shell Scripting in DevOps

• Automates infrastructure and configuration management tasks.
• Example: Monitoring node health across multiple virtual machines.
• Shell scripts can log into machines, check system parameters, and notify users about issues.

Common Use Cases for Shell Scripting in DevOps

• Automating routine monitoring tasks (CPU, memory usage).
• Facilitate interactions with Git and other Linux-based tools.
• Configuration management for various applications/services.

Advanced Topics (To Explore Later)

• Handling signals in scripts (using trap).
• Writing cron jobs for scheduled tasks.

Conclusion

• Shell scripting is an essential skill for DevOps engineers.
• Encourages hands-on practice to solidify understanding.
• Feedback requested for advanced topics.

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