📘 Git & GitHub Complete Notes

📑 Table of Contents

• Introduction
• Git Basics
• Git Commands
• GitHub Basics
• GitHub Commands
• Working with Remote Repositories
• Branching and Merging
• Common Errors and Fixes
• Useful Tips

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🔰 Introduction

• Git is a version control system for tracking changes in source code.
• GitHub is a cloud-based hosting platform for Git repositories to collaborate and share code.

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🔵 Git Basics

• Tracks changes in source code.
• Used for collaboration on coding projects.
• Local operations, distributed system.

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💻 Git Commands

✅ Basic Git Setup

git --version                    # Check Git version
git config --global user.name "Your Name"    # Set Git username
git config --global user.email "you@example.com" # Set Git email

✅ Initialize Repository

git init                         # Initialize a local Git repository

✅ Basic Workflow

git status                       # Check status
git add <filename>               # Stage file
git add .                        # Stage all files
git commit -m "Commit message"   # Commit changes

✅ View Logs & History

git log                          # Show commit logs
git log --oneline                # One-line log format

✅ File Operations

git rm <file>                    # Remove file
git mv <old> <new>               # Rename file

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🟣 GitHub Basics

• Online platform to store repositories.
• Offers collaboration tools like Pull Requests, Issues, Wiki, Actions.
• Remote storage for Git repositories.

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🟢 GitHub Commands

✅ Connecting Local Repo to GitHub

git remote add origin https://github.com/username/repo.git  # Add remote repo
git remote -v                      # Verify remote URL

✅ Pushing and Pulling

git push -u origin main             # Push initial commit to GitHub
git pull origin main               # Pull updates from GitHub
git push                           # Push changes

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🌐 Working with Remote Repositories

✅ Clone Repositories

git clone https://github.com/username/repo.git  # Clone repo

✅ Fetch & Merge Changes

git fetch                           # Download changes
git merge origin/main               # Merge fetched changes
git pull                            # Fetch + merge in one command

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🌿 Branching and Merging

✅ Branch Operations

git branch                          # List branches
git branch <branch-name>            # Create branch
git checkout <branch-name>          # Switch to branch
git checkout -b <branch-name>       # Create & switch to branch

✅ Merging Branches

git merge <branch-name>             # Merge branch into current

✅ Delete Branch

git branch -d <branch-name>         # Delete branch locally

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👩🏻‍💻create a new repository on the command line

echo "# Your_Repository_Name" >> README.md                                    # 1. Create a README file
git init                                                                      # 2. Initialize Git
git add README.md                                                             # 3. Add Files to Staging Area
git commit -m "your commit message"                                           # 4. Commit Changes
git branch -M main                                                            # 5. Rename the Branch to 'main'
git remote add origin https://github.com/your-username/your-repository.git    # 6. Add Remote Repository
git push -u origin main                                                       # 7. Push Changes to GitHub

🔄 Push an Existing Local Repository

git remote add origin https://github.com/your-username/your-repository.git
git branch -M main
git push -u origin main

⚠️ Common Errors and Fixes

Error	Fix Command
Updates were rejected because the remote contains work...	git pull --rebase origin main
fatal: refusing to merge unrelated histories	git pull origin main --allow-unrelated-histories
error: failed to push some refs to 'url'	git pull --rebase origin main or fix conflicts, then git push
Mistaken commit message	git commit --amend
Push to wrong branch	git push origin <correct-branch>

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💡 Useful Tips

• Check Configurations

git config --list                   # List all configurations

• Undo Last Commit (Keep Changes)

git reset --soft HEAD~1

• Undo Last Commit (Remove Changes)

git reset --hard HEAD~1

• Create .gitignore file to ignore specific files/folders.

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🚀 Example Workflow

git init
git add .
git commit -m "Initial commit"
git branch -M main
git remote add origin https://github.com/username/repo.git
git push -u origin main

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🌟 Useful Links

• Git Official Documentation
• GitHub Docs
• Git Cheat Sheet

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📬 Contact

Made with ❤️ by Selvaneyas

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