Git Overview

Git is a distributed version control system used to track changes, collaborate on software, manage infrastructure as code, and support modern DevOps workflows. GitHub builds on Git by providing repositories, pull requests, code reviews, automation, security scanning, and collaboration features.

Git Architecture

Git stores snapshots of files in a directed graph of commits. Every clone contains the full repository history, enabling offline work, branching, merging, and recovery.

Working Directory → Staging Area → Local Repository → Remote Repository (GitHub)

Installation & Configuration

git --version
git config --global user.name "Jane Doe"
git config --global user.email "jane@example.com"
git config --global init.defaultBranch main
git config --global pull.rebase false

Repositories

Initialize or clone repositories, keep a clean directory structure, use .gitignore, and commit small logical changes.

git init
git clone https://github.com/org/project.git
git status
git add .
git commit -m "Initial commit"

Commits

Each commit should represent one logical change with a descriptive message. Avoid mixing unrelated changes.

Branches

git switch -c feature/login
git switch main
git branch -a

Feature branches isolate work until it is reviewed and merged.

Merge & Rebase

Use merge to preserve branch history and rebase to create a linear history where appropriate. Avoid rebasing shared branches.

git merge feature/login
git rebase main

Tags & Releases

git tag v1.0.0
git push origin v1.0.0

Remote Repositories

git remote -v
git fetch
git pull
git push origin main

GitHub

Use pull requests, code owners, protected branches, issues, projects, releases, secret scanning and Dependabot to improve software quality and security.

Pull Requests

Require reviews, automated checks, and passing CI before merging.

Branching Strategies

Common enterprise approaches include GitHub Flow, Git Flow and Trunk-Based Development. Choose one strategy consistently across teams.

GitHub Actions

name: CI
on: [pull_request]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: echo "Run tests here"

Security Best Practices

• Protect main branches.
• Enable MFA.
• Use SSH keys or passkeys.
• Sign commits where required.
• Never commit secrets.
• Enable secret scanning and Dependabot.

Troubleshooting

git status
git log --oneline --graph
git reflog
git restore .
git reset --hard HEAD~1
git stash
git stash pop

Essential Commands

git init
git clone
git status
git add
git commit
git log
git diff
git switch
git checkout
git branch
git merge
git rebase
git cherry-pick
git tag
git fetch
git pull
git push
git stash
git reflog
git reset
git revert

Key Takeaways

Git is the foundation of modern DevOps. Combined with GitHub, protected branches, reviews, CI/CD, and security controls, it enables reliable, auditable, and repeatable software delivery.