Why Git?

Git is a fast, distributed version-control system that records snapshots (commits) of your project, enabling parallel development through lightweight branching and allowing complete history on every clone .

1.1 Install

macOS (Homebrew): brew install git

Ubuntu / Debian: sudo apt-get install git

Windows: Download the installer from git-scm.com and follow the wizard.

1.2 Initial Configuration

git config --global user.name "Jane Developer"
git config --global user.email "jane@example.com"
git config --global init.defaultBranch main
git config --global core.editor "nano -w"

Notes: init.defaultBranch replaces the legacy master branch name for new repos.

2.1 The Three-Tree Architecture

Working Directory → Index → Repository  — Edit files, stage changes, then commit snapshots.

2.2 Objects

Everything is a blob, tree, commit or tag. Objects are content-addressed by SHA-1 or SHA-256 (experimental) hashes, guaranteeing integrity.

2.3 Branches & HEAD

A branch is a movable pointer to a commit. HEAD is your current checkout.

2.4 References Storage

Since Git 2.45 you can opt-in to the reftable backend for faster reference look-ups: git init --ref-format=reftable .

3.1 Quick Reference Table

Command	Description	Syntax Example
git status	Show staged / unstaged changes	git status
git add	Stage files	git add README.md
git commit	Record snapshot	git commit -m "feat: initial"
git log	View history	git log --oneline --graph

3.2 Cloning & Creating Repositories

Create new repo: git init

Clone remote: git clone https://example.com/project.git

3.3 Viewing Changes

Diff working vs index: git diff

Diff index vs HEAD: git diff --cached

4.1 Create & Switch

Create branch: git branch feature/login

Switch (≥Git 2.23): git switch feature/login

4.2 Merge

Fast-forward: git merge feature/login

Three-way merge when histories diverge. Conflicts appear in-file; resolve then git add and commit.

4.3 Rebase

Linearize history: git rebase main

Notes: Never rebase commits that others have already pulled.

4.4 Cherry-Pick & Revert

Apply single commit: git cherry-pick <sha>

Undo with new commit: git revert <sha>

5.1 Remotes

Add remote: git remote add origin git@github.com:user/repo.git

Rename: git remote rename origin production

5.2 Synchronizing

Fetch: git fetch downloads refs, no merge.

Pull: git pull --rebase fetch + rebase for cleaner history.

Push: git push -u origin main

5.3 Tracking Branches

git checkout -b feature/ui --track origin/feature/ui

6.1 Reflog

View all head movements: git reflog. Recover deleted branches by resetting to a reflog entry.

6.2 Reset

Soft: keep index; Mixed (default): keep working dir; Hard: discard everything.

git reset --hard HEAD~1

6.3 Bisect

Binary search for a bad commit:

git bisect start
git bisect bad
git bisect good v1.2.0

7.1 Stash

Save work: git stash push -m "wip: fix bug"

Apply latest: git stash pop

7.2 Tagging

Lightweight: git tag v1.0.0

Annotated (signed): git tag -a v1.0.0 -m "First stable" -s

8.1 Local Hooks

Place executable scripts in .git/hooks/ (e.g., pre-commit, pre-push).

8.2 Server-Side Hooks

Enforce policies like branch-naming or commit message linting on the remote.

9.1 Partial Clone

Download only referenced objects: git clone --filter=blob:none --depth=1 url. Great for monorepos .

9.2 Sparse Checkout

Limit working directory to specific paths:

git sparse-checkout init --cone
git sparse-checkout set src/ docs/

9.3 Scalar

Microsoft’s Scalar enables background prefetch, partial clone defaults and repo maintenance for massive projects .

9.4 Git LFS

Track large binaries outside the main object store: git lfs track "*.psd" followed by commit and push.

10.1 Signed Commits & Tags

GPG: git commit -S -m "secure"

X.509 (S/MIME): git config --global gpg.format x509

10.2 Credential Helpers

Cache for session: git config --global credential.helper cache

macOS Keychain: git config --global credential.helper osxkeychain

10.3 Certificate-Based Auth

Git 2.44 added first-class certificate authentication for enterprises .

11.1 Reftable Backend

Experimental backend for references, improving performance on repos with many branches .

11.2 SHA-256 Interoperability

Prepare for stronger hashing; mixed SHA-1/SHA-256 repos now interoperable (opt-in).

11.3 Enhanced Sparse-Checkout UI

Commands like git sparse-checkout reconfigure simplify path-set updates.

11.4 Security & UX

Certificate auth, default protected configs, clearer advice messages and improved git pull conflict hints .

12.1 Feature Branch Flow

Develop each feature on its own branch, merge via pull request, protect main.

12.2 GitHub Flow

Short-lived branches, continuous deployment, squash-merge for tidy history.

12.3 Gitflow (NVIE)

Separate develop, release, hotfix branches; suited to versioned products.

12.4 Trunk-Based Development

Commit small increments directly to main behind feature flags; ideal for micro-services.

13.1 Official Docs

git-scm.com/docs — exhaustive command manual.

13.2 Pro Git Book

The freely available book by Chacon & Straub covers everything from basics to internals.

13.3 Interactive Tutorials

Web-based sandboxes such as learngitbranching.js.org let you practice without risk.

14.1 Scaffold & First Commit

Directory layout:

cpp-app/
  src/ main.cpp
  include/ utils.hpp
  CMakeLists.txt

git init
git add .
git commit -m "chore: bootstrap C++ app"

14.2 Ignore Build Artifacts

echo -e "build/\n*.o\n*.exe" >> .gitignore

git add .gitignore
git commit -m "chore: add ignore rules"

14.3 Feature Branch Example

git switch -c feature/cli-parser
# code changes …
git add src/cli.cpp include/cli.hpp
git commit -m "feat: add ArgParser"

Merge back to main after tests pass:

git switch main
git merge --no-ff feature/cli-parser -m "feat: ArgParser"

15.1 Initial Commit

Directory layout:

web-site/
  index.html
  css/ styles.css
  js/ main.js

git init
git add index.html css js
git commit -m "feat: landing page skeleton"

15.2 Ignore Generated Assets

echo -e "dist/\nnode_modules/\n.env" >> .gitignore

git add .gitignore
git commit -m "chore: ignore build output"

15.3 Iterative Development with Branches

git switch -c feature/hero-animation
# edit css/animations.css + js/scroll.js
git add css js
git commit -m "feat: add hero section animation"

Rebase onto the freshest main before opening a pull request:

git fetch origin
git rebase origin/main

Resolve conflicts if they occur, then push the branch:

git push -u origin feature/hero-animation