Version Control Systems

AESB2122 - Signals and Systems with Python

Geet George

Problems Without Version Control

You probably have faced the following issues, but think about such problems in a larger project with many collaborators.

The Problem of File Versions

  • report.docx
  • report_final.docx
  • report_final2_reallyfinal.docx
  • report_final2_reallyfinal_v2.docx
  • report_final2_reallyfinal_v2_fixed.docx

Which one to use? 🤔

Naive Solutions

  • Save copies in different folders
  • Email files to yourself
  • Rename with dates:
    • project_2025-09-09.docx

Easy to lose track and errors can creep in

Collaboration Problem

  • Person A edits the file
  • Person B edits the same file
  • A overwrites B’s changes

Whose version is correct?

Accidental Deletions

  • Mistakenly overwrite or delete a file
  • Without backup → work is gone

We want a “time machine”!

Tracking Changes

  • Want to compare version 1 vs version 2
  • See: who changed what, when, and why
  • Plain files don’t remember this info

Scaling Up: Software Projects

  • Hundreds of files (code, docs, configs)
  • Many contributors
  • Manual versioning impossible 🚫

Real-time editing tools

  • Google Docs, Overleaf, etc.
  • Easy to overwrite changes, no track history usually
  • Not suitable for code projects

What We Want (Wish List)

  • Automatic version history
  • Collaboration without overwriting
  • Merge changes intelligently
  • Track who–when–why
  • Work offline, sync later

Version Control Systems (VCS)

Tool that records changes to files over time.

Allows you to:
- Revert to previous versions
- Work together safely keeping track of changes
- Merge changes intelligently

Simple Example

  • Student edits a file → commit “Added intro”
  • Later, another commit → “Fixed typo”
  • Both changes are saved with history

---
config:
  theme: base
  commitLabelFontSize: '16px'
---
gitGraph
   commit id: "Added intro"
   commit id: "Fixed typo"

Branching Example

  • Main version = stable
  • You come up with an idea for a new feature - create a branch
  • If good → merge back
  • If bad → discard, main (original stable version) stays safe

---
config:
  theme: base
---
gitGraph
    commit id: "stable version"
    branch new-feature
    checkout new-feature
    commit id: "Tried new feature"
    commit id: "Improved new feature"
    checkout main
    merge new-feature id: "Merged changes"

Branches can also be abandoned

gitGraph
    checkout main
    commit id: "stable version"
    branch new-feature
    checkout new-feature
    commit id: "Tried new feature"
    commit id: "Improved new feature"
    branch risky-idea
    checkout risky-idea
    commit id: "Tried risky idea"
    commit id: "Tried improved risky idea"
    checkout main
    merge new-feature id: "Merged changes"

Extra Benefits (with remote repositories)

  • Access files from anywhere
  • Backup (remote repositories)
  • See who contributed what
  • Enables global collaboration (open source)

Exercise

Setup Git

  1. Check if you have Git installed:
    • Open a terminal and run: git --version
    • If it shows a version number, Git is installed. If not, follow the steps below.
  2. Install Git on your computer (if not already installed):
    • Windows: Git for Windows
    • macOS: Use Homebrew: brew install git
    • Linux: Use your package manager, e.g., sudo apt-get install git
  3. Set up Git (one-time configuration):

    • Open a terminal and run:

      git config --global user.name "Your Name"
git config --global user.email "your_email@example.com"

    • Replace "Your Name" and "your_email@example.com" with your actual name and email address. Keep the double quotes.

Setup Github

  1. Create a GitHub account if you don’t have one. You can use your university email.

  2. Add your SSH key to GitHub for secure authentication:

NOTE!

If git is not recognized as a command (e.g. in VS Code, Jupyter, etc.), you may need to restart your terminal or computer after installation.