#Git Fundamentals

Git is the industry standard for version control. Every DevOps engineer must master Git.

#📋 Table of Contents

Git Basics
Working with Repositories
Commits and History
Branching
Remote Repositories
Undoing Changes
Git Configuration

#Git Basics

#Installing Git

bash

1# Ubuntu/Debian
2sudo apt install git
3
4# macOS
5brew install git
6
7# Windows
8choco install git
9
10# Verify
11git --version

#Initial Configuration

bash

1# Set identity
2git config --global user.name "Your Name"
3git config --global user.email "your.email@example.com"
4
5# Default branch name
6git config --global init.defaultBranch main
7
8# Editor
9git config --global core.editor "vim"
10
11# View config
12git config --list

#Working with Repositories

#Creating a Repository

bash

1# Initialize new repository
2mkdir my-project
3cd my-project
4git init
5
6# Clone existing repository
7git clone https://github.com/user/repo.git
8git clone git@github.com:user/repo.git  # SSH

#Basic Workflow

bash

1# Check status
2git status
3
4# Stage files
5git add file.txt           # Single file
6git add .                   # All files
7git add *.py               # Pattern
8
9# Commit
10git commit -m "Add feature X"
11
12# Stage and commit together
13git commit -am "Update existing files"

#Commits and History

#Creating Good Commits

bash

1# Good commit message format
2git commit -m "feat: add user authentication
3
4- Implement JWT token generation
5- Add login/logout endpoints
6- Include password hashing"

#Conventional Commits

Type	Description
`feat`	New feature
`fix`	Bug fix
`docs`	Documentation
`style`	Formatting
`refactor`	Code refactoring
`test`	Adding tests
`chore`	Maintenance

#Viewing History

bash

1# View log
2git log
3git log --oneline
4git log --graph --oneline --all
5
6# Show specific commit
7git show abc1234
8
9# View changes in file
10git log -p file.txt
11
12# Search commits
13git log --grep="feature"
14git log --author="John"

#Branching

#Branch Operations

bash

1# List branches
2git branch
3git branch -a  # Include remote
4
5# Create branch
6git branch feature-login
7
8# Switch branch
9git checkout feature-login
10git switch feature-login     # Modern syntax
11
12# Create and switch
13git checkout -b feature-login
14git switch -c feature-login
15
16# Delete branch
17git branch -d feature-login   # Safe delete
18git branch -D feature-login   # Force delete

#Merging

bash

1# Merge branch into current
2git checkout main
3git merge feature-login
4
5# Merge with no fast-forward (creates merge commit)
6git merge --no-ff feature-login
7
8# Abort merge
9git merge --abort

#Rebasing

bash

1# Rebase current branch onto main
2git checkout feature-login
3git rebase main
4
5# Interactive rebase (squash commits)
6git rebase -i HEAD~3
7
8# Continue after resolving conflicts
9git rebase --continue
10
11# Abort rebase
12git rebase --abort

#Remote Repositories

#Working with Remotes

bash

1# List remotes
2git remote -v
3
4# Add remote
5git remote add origin https://github.com/user/repo.git
6
7# Change remote URL
8git remote set-url origin new-url
9
10# Remove remote
11git remote remove origin

#Push and Pull

bash

1# Push to remote
2git push origin main
3git push -u origin main  # Set upstream
4
5# Push all branches
6git push --all
7
8# Pull from remote
9git pull origin main
10
11# Fetch without merging
12git fetch origin
13git fetch --all

#Pull Requests Workflow

bash

1# 1. Create feature branch
2git checkout -b feature-x
3
4# 2. Make changes and commit
5git add .
6git commit -m "feat: implement feature X"
7
8# 3. Push branch
9git push -u origin feature-x
10
11# 4. Create pull request on GitHub/GitLab
12
13# 5. After merge, cleanup
14git checkout main
15git pull
16git branch -d feature-x

#Undoing Changes

#Unstaging Files

bash

# Unstage file
git restore --staged file.txt
git reset HEAD file.txt  # Old syntax

#Discarding Changes

bash

1# Discard working directory changes
2git restore file.txt
3git checkout -- file.txt  # Old syntax
4
5# Discard all changes
6git restore .

#Reverting Commits

bash

1# Create new commit that undoes previous
2git revert abc1234
3
4# Revert without committing
5git revert --no-commit abc1234

#Resetting

bash

1# Soft reset (keep changes staged)
2git reset --soft HEAD~1
3
4# Mixed reset (keep changes unstaged)
5git reset HEAD~1
6
7# Hard reset (discard changes)
8git reset --hard HEAD~1
9
10# Reset to remote
11git reset --hard origin/main

#Git Configuration

#SSH Keys

bash

1# Generate SSH key
2ssh-keygen -t ed25519 -C "your.email@example.com"
3
4# View public key
5cat ~/.ssh/id_ed25519.pub
6
7# Test connection
8ssh -T git@github.com

#.gitignore

gitignore

1# Dependencies
2node_modules/
3vendor/
4__pycache__/
5
6# Build output
7dist/
8build/
9*.pyc
10
11# IDE
12.idea/
13.vscode/
14*.swp
15
16# Environment
17.env
18.env.local
19*.log
20
21# OS
22.DS_Store
23Thumbs.db

#Aliases

bash

1git config --global alias.co checkout
2git config --global alias.br branch
3git config --global alias.ci commit
4git config --global alias.st status
5git config --global alias.lg "log --oneline --graph --all"

#Summary

Action	Command
Initialize	`git init`
Clone	`git clone url`
Stage	`git add .`
Commit	`git commit -m "msg"`
Push	`git push origin main`
Pull	`git pull`
Branch	`git checkout -b name`
Merge	`git merge branch`
Status	`git status`
Log	`git log --oneline`

[!TIP] Pro Tip: Use git stash to temporarily save changes when switching branches!