Introduction

This tutorial aims to guide you through creating automation pipelines using shell scripts. Automation pipelines are crucial in Continuous Integration/Continuous Deployment (CI/CD) environments as they automate the testing and deployment processes, making them more efficient and less prone to human error.

By the end of this tutorial, you will have learned:
- Basic shell scripting
- How to create shell scripts for automation pipelines
- How to use these scripts to automate tasks

Prerequisites: Basic knowledge of Linux command line and an understanding of the software development process.

Step-by-Step Guide

Shell scripts are a powerful tool for automating tasks on UNIX-like operating systems. They are simply files containing a sequence of commands for a UNIX-based operating system.

Here's a step-by-step guide to creating automation pipelines with shell scripts:

1. Understanding Your Workflow

   Before you start writing your shell script, you need to have a clear understanding of the tasks you want to automate. It could be testing your code, deploying your application, or any other task involved in your development process.

2. Writing Your Shell Script

   Create a new file with a .sh extension. This will be your shell script. In this file, you'll write a series of commands that you would normally run in your terminal.

   Here's a simple example:

   ```bash

   !/bin/bash

   echo "Automation pipeline has started"

   navigate to project directory

   cd /path/to/your/project

   run tests

   python -m unittest discover

   echo "Automation pipeline has finished"
   ```

   Remember to start your file with the #!/bin/bash line. This is called a shebang, and it specifies that the script should be run with the bash shell. The echo command prints a line of text to the terminal, the cd command changes the current directory, and the python -m unittest discover line runs all the tests in the project.

3. Running Your Shell Script

   You can run your shell script from the terminal with the following command: bash yourScript.sh.

   If you want to run the script with a simple ./yourScript.sh, you will need to make it executable with the chmod command: chmod +x yourScript.sh.

Code Examples

Here are a few more examples of what you can do with shell scripts in your automation pipeline:

Example 1: Automating Git Commands

#!/bin/bash

# navigate to project directory
cd /path/to/your/project

# add all changes to staging area
git add .

# commit changes with a message
git commit -m "Automated commit"

# push changes to remote repository
git push origin main

This script automates the process of committing changes to a git repository and pushing them to a remote repository.

Example 2: Building and Running a Docker Container

#!/bin/bash

# build docker image
docker build -t my-app .

# run docker container
docker run -p 5000:5000 my-app

This script builds a Docker image from a Dockerfile in the current directory and runs a container from it.

Summary

In this tutorial, you've learned the basics of shell scripting and how to use it to create automation pipelines. You've learned how to write a shell script, how to run it, and saw a few examples of scripts that automate git commands and Docker operations.

For further learning, you could explore more complex scripts and how to use shell scripting in combination with other tools like Jenkins, Travis CI, or CircleCI.

Practice Exercises

1. Write a shell script that takes a filename as an argument and prints the number of lines in that file.

2. Write a shell script that takes a directory name as an argument and prints the number of files in that directory.

3. Write a shell script that automates the process of cloning a git repository, navigating into it, creating a new branch, and checking out that branch.

Check out resources like ShellCheck for helping you write better scripts, and Bash Academy for learning more about bash scripting.