Agenda

• Agenda
• Version Control Systems (VCS)
  • Centralized Version Control Systems
  • Distributed Version Control Systems
• What is Git?
• How Git Works
• Git Setup & Important Git commands
• Visualizing Git
• Resources

Version Control Systems (VCS)

• Track Changes:
  • Helps developers manage changes to source code over time.
  • Records every modification made to the codebase.
• Collaboration:
  • Helps multiple developers to work on the same project simultaneously without overwriting each other’s work.
  • Important because code development is not a linear process.
• History and Reversion:
  • Maintains history of changes, allowing developers to revert to previous versions if needed.

Centralized Version Control Systems

• Single Central Repository: All users work with a single central repository, typically hosted on a server.
• Commit and Update: Developers commit their changes to this central repository and update their local copies to stay in sync with others.
• Pro:
  • Simplified Management - Since all changes are tracked in a single central repository, it’s easier to manage and control the code base.
• Con:
  • Single Point of Failure - If the central server goes down or becomes inaccessible, no one can commit changes or access the latest version of the code.

Distributed Version Control Systems

• Local Repositories: Each developer has a complete copy of the repository, including the full history of changes.
• Peer-to-Peer: Changes are shared between repositories, allowing for more flexible workflows and offline work.
• Pro:
  • Enhanced Collaboration - Each developer has a full copy of the repository, allowing for more flexible workflows, offline work, and easier branching and merging.
• Con:
  • Complexity - Managing multiple copies of the repository and coordinating changes between them can be more complex and require more sophisticated tools and practices.

What is Git?

• Git is a popular, free, and open-source Distributed Version Control System!
  • Collaboration
  • Version History
  • Backup and Recovery
  • Offline Work
  • Conflict Resolution

[!NOTE] Git is everywhere! According to the Stack Overflow Developer Survey 2022, 95% of developers reported Git as their primary version control system.

How Git Works

1. Local Repository: You have a repository on your local machine where you keep your files. This is your personal workspace where you make changes and save versions of your files.
2. Remote Repository: There’s also a repository on a server (like GitHub, GitLab, or Bitbucket). This acts as a central hub where you can store your files and share them with others.
3. Synchronization: You can synchronize your local repository with the remote one. This means you can upload your changes to the server (push) and download changes from the server (pull).
4. Collaboration: If you’re working with others, they can also upload their changes to the remote repository. You can then download these changes to your local repository.

Git Setup & Important Git commands

1. Install Git

   1. Download and install Git from git-scm.
   2. Verify installation by running the command below in your terminal:

      git --version   

2. Configure Git

   1. Set your username and email:

      git config --global user.name "Your Name"
      git config --global user.email "[email protected]"

3. Initialize a Repository

   1. Navigate to your project directory and initialize Git:

      cd /path/to/your/project
      git init

4. Check status

   git status

5. Add Git Ignore (optional)

6. Stage changed files

   git add filename

7. Commit staged files

   git commit -m "Your commit message"

8. Create a Remote Repository

   1. Create a repository on a platform like GitHub.
   2. Link your local repo to the remote repo:

      git remote add origin https://github.com/yourusername/your-repo.git

9. Push changes to the Remote Repository

   1. Push your changes:

      git push -u origin master

   [!NOTE] Git Forks

   • The -u (same as --set-upstream) in git push is used to set the fork to be used. In the previous command, origin is the name of the fork and master is the name of the branch.

   • What are Git Forks?

     • Independent Copies: A Git fork is a complete copy of a repository that exists independently from the original.
     • Separate Development: It allows developers to work on their own version of the project without affecting the original repository.
     • Branches: Each fork can have its own branches, enabling multiple lines of development.

   • Why are Git Forks Used?

     • Experimentation: Developers can test new features or changes in their own fork without risking the stability of the main project.
     • Collaboration: Forks enable multiple developers to work on the same project simultaneously, each in their own space, before merging changes back into the original repository.

10. Pull Changes from the Remote Repository

    git pull origin master

11. Branching

    1. Create a new branch

       git branch new-branch  

    2. Checkout (switch) to the new or an existing branch

       git checkout new-branch

12. Merge Branches

    1. Switch to the main branch

       git checkout master

    2. Merge the new branch into the main branch

        git merge new-branch

13. View Commit History

    git log

14. Cloning an existing Repository

    git clone https://github.com/yourusername/your-repo.git

    [!NOTE] Git Submodules

    • Git submodules are a way to include one Git repository inside another as a subdirectory. This allows you to keep a separate project within your main project while maintaining its own version control.
    • To clone a Git Repo with Submodules:

    git clone --recurse-submodules https://github.com/yourusername/your-repo.git

15. Git Merge

    1. Switch to the branch you want to merge into

       git checkout master

    2. Merge the feature branch into the master branch

       git merge feature-branch

    [!NOTE] Better Practice: Use Pull (Merge) Requests

    • Code Review: Pull requests give other developers a chance to review the code before merging.
    • Discussion: They provide a platform for discussing changes and suggesting improvements.
    • Testing: Ensures that the code passes all tests and meets the project's standards before being merged. (CI/CD)
    • Documentation: Pull requests serve as documentation for why changes were made and how they were implemented.

Visualizing Git

Visualizing Git Concepts with D3

Resources

1. Centralized vs Distributed Version Control Systems | Medium
2. A Simple Introduction to Git | CS 5010 | Northeastern University
3. Stack Overflow Developer Survey 2022