DevOps / Version Control

Git & GitHub Mastery

The complete guide to version control. Master Git commands, branching strategies, collaboration workflows, and GitHub features.

By Ramjee Prasad•December 15, 2025•20 min read

1. Git Fundamentals
2. Git Configuration
3. Essential Commands
4. Branching & Merging
5. Merge vs Rebase

6. Remote Repositories
7. GitHub Essentials
8. Undoing Changes
9. Git Workflows
10. Best Practices

1. Git Fundamentals

Git is a distributed version control system that tracks changes in your code. Unlike centralized systems, every developer has a full copy of the repository.

Key Concepts

Repository: Project folder tracked by Git

Commit: Snapshot of your changes

Branch: Parallel version of your code

Remote: Server-hosted repository (GitHub)

Clone: Copy of a remote repository

Pull/Push: Sync with remote

Initialize a New Repository

# Create new repository
git init

# Or clone existing repository
git clone https://github.com/username/repo.git

# Clone with specific branch
git clone -b develop https://github.com/username/repo.git

2. Git Configuration

Set User Identity

# Set your name (required for commits)
git config --global user.name "Ramjee Prasad"

# Set your email
git config --global user.email "ashish23481@gmail.com"

# View all config
git config --list

Configure your identity for all repositories on this machine.

SSH Key Setup

# Generate SSH key
ssh-keygen -t ed25519 -C "your_email@example.com"

# Start SSH agent
eval "$(ssh-agent -s)"

# Add key to agent
ssh-add ~/.ssh/id_ed25519

# Copy public key to clipboard (add to GitHub)
cat ~/.ssh/id_ed25519.pub

Set up SSH for secure authentication with GitHub.

Useful Aliases

# Create shortcuts for common commands
git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.ci commit
git config --global alias.st status
git config --global alias.lg "log --oneline --graph --all"

Save time with custom command shortcuts.

3. Essential Commands

Check Status

git status

# Short format
git status -s

View the state of your working directory and staging area.

Stage Changes

# Stage specific file
git add filename.txt

# Stage all changes
git add .

# Stage all changes including deletions
git add -A

# Interactive staging
git add -p

Add changes to the staging area before committing.

Commit Changes

# Commit with message
git commit -m "Add user authentication feature"

# Commit all tracked changes
git commit -am "Quick fix for login bug"

# Amend last commit
git commit --amend -m "Updated commit message"

# Empty commit (useful for triggering CI)
git commit --allow-empty -m "Trigger build"

Save your staged changes with a descriptive message.

View History

# View commit log
git log

# One line per commit
git log --oneline

# Graph view with branches
git log --oneline --graph --all

# Show last 5 commits
git log -5

# Show commits by author
git log --author="Ramjee"

Browse the commit history of your repository.

View Differences

# Unstaged changes
git diff

# Staged changes
git diff --staged

# Between branches
git diff main..feature-branch

# Specific file
git diff filename.txt

Compare changes between commits, branches, or files.

Stash Changes

# Save work in progress
git stash

# With description
git stash push -m "WIP: new feature"

# List stashes
git stash list

# Apply latest stash
git stash pop

# Apply specific stash
git stash apply stash@{2}

# Drop stash
git stash drop stash@{0}

Temporarily save uncommitted changes.

4. Branching & Merging

Branch Operations

# List branches
git branch

# List all (including remote)
git branch -a

# Create new branch
git branch feature-login

# Switch to branch
git checkout feature-login

# Create and switch (shortcut)
git checkout -b feature-login

# Modern way (Git 2.23+)
git switch -c feature-login

# Delete branch
git branch -d feature-login

# Force delete
git branch -D feature-login

Create, list, switch, and delete branches.

Merge Branches

# Switch to target branch
git checkout main

# Merge feature branch
git merge feature-login

# Merge with commit message
git merge feature-login -m "Merge feature-login into main"

# Merge without fast-forward
git merge --no-ff feature-login

# Abort merge
git merge --abort

Combine changes from different branches.

5. Merge vs Rebase

Git Merge

Creates a merge commit, preserves history exactly as it happened.

git checkout main
git merge feature

✓ Safe, non-destructive
✓ Shows complete history

Git Rebase

Re-applies commits on top of another branch, creates linear history.

git checkout feature
git rebase main

✓ Clean, linear history
⚠ Don't rebase public branches

Interactive Rebase

# Rebase last 3 commits
git rebase -i HEAD~3

# Commands in interactive mode:
# pick   = use commit
# reword = use commit, edit message
# squash = meld into previous commit
# drop   = remove commit

Modify, combine, or remove commits in your history.

6. Remote Repositories

Remote Management

# View remotes
git remote -v

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

# Change remote URL
git remote set-url origin git@github.com:user/repo.git

# Remove remote
git remote remove origin

Manage connections to remote repositories.

Push & Pull

# Push to remote
git push origin main

# Push and set upstream
git push -u origin main

# Force push (use carefully!)
git push --force-with-lease

# Pull changes
git pull origin main

# Pull with rebase
git pull --rebase origin main

Sync your local repository with the remote.

Fetch & Prune

# Fetch all branches
git fetch origin

# Fetch and prune deleted branches
git fetch --prune

# Delete local branches that are gone on remote
git branch -vv | grep ': gone]' | awk '{print $1}' | xargs git branch -d

Download remote changes without merging.

7. GitHub Essentials

Fork & Clone Workflow

# 1. Fork repo on GitHub (web)

# 2. Clone your fork
git clone git@github.com:YOUR_USER/repo.git

# 3. Add upstream remote
git remote add upstream https://github.com/ORIGINAL_OWNER/repo.git

# 4. Sync with upstream
git fetch upstream
git checkout main
git merge upstream/main

Contribute to open source projects.

Pull Request Workflow

# 1. Create feature branch
git checkout -b feature/new-feature

# 2. Make changes and commit
git add .
git commit -m "Add new feature"

# 3. Push to your fork
git push origin feature/new-feature

# 4. Create PR on GitHub (web)

# 5. After PR merge, cleanup
git checkout main
git pull origin main
git branch -d feature/new-feature

Standard workflow for contributing via pull requests.

GitHub CLI (gh)

# Install: https://cli.github.com

# Login
gh auth login

# Create PR from terminal
gh pr create --title "Add feature" --body "Description"

# List PRs
gh pr list

# Checkout PR locally
gh pr checkout 123

# Merge PR
gh pr merge 123

8. Undoing Changes

⚠️ Warning: Some of these commands rewrite history. Never rewrite history on shared/public branches!

Discard Local Changes

# Discard changes in working directory
git checkout -- filename.txt

# Discard all changes
git checkout -- .

# Modern way
git restore filename.txt

Discard uncommitted changes to files.

Unstage Files

# Unstage file
git reset HEAD filename.txt

# Modern way
git restore --staged filename.txt

# Unstage all
git reset HEAD

Remove files from staging area without losing changes.

Reset Commits

# Soft reset (keep changes staged)
git reset --soft HEAD~1

# Mixed reset (keep changes unstaged)
git reset HEAD~1

# Hard reset (discard everything!)
git reset --hard HEAD~1

# Reset to specific commit
git reset --hard abc1234

Move HEAD to a different commit. Be careful with --hard!

Revert Commits

# Create new commit that undoes changes
git revert HEAD

# Revert specific commit
git revert abc1234

# Revert multiple commits
git revert HEAD~3..HEAD

Safely undo commits by creating a new commit (safe for shared branches).

9. Git Workflows

GitHub Flow (Simple)

Best for continuous deployment. Simple and effective.

main ──────●──────●──────●──────●──────
             \            /
feature       ●────●────●

Create branch from main
Make commits
Open Pull Request
Review & Merge
Delete branch

Git Flow (Release-based)

Best for scheduled releases with multiple environments.

main    ─────●─────────────────●─────
              \               /
release        ●─────●───────●
                \     \     /
develop  ●──●───●──●───●───●───●──
          \    /  \       /
feature    ●──●    ●─────●

Branches: main, develop, feature/*, release/*, hotfix/*

10. Best Practices

Commit Messages

# Good commit message format
<type>(<scope>): <subject>

<body>

<footer>

# Examples:
feat(auth): add JWT authentication
fix(api): resolve null pointer in user service
docs(readme): update installation steps
refactor(core): simplify database queries

General Tips

✓ Commit early, commit often
✓ Write meaningful commit messages
✓ Use feature branches
✓ Pull before you push
✓ Never commit secrets/passwords
✓ Use .gitignore for build files
✓ Review code before merging
✓ Keep commits atomic (one thing per commit)

.gitignore Template

.gitignore

# IDE
.idea/
.vscode/
*.iml

# Build
target/
build/
dist/
node_modules/

# Environment
.env
.env.local
*.log

# OS files
.DS_Store
Thumbs.db

# Compiled
*.class
*.jar
*.war

Written by Ramjee Prasad • Backend Developer

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