Getting Started with GitHub¶

1. What is GitHub?¶

GitHub is a web service that hosts Git repositories.

Key Features of GitHub¶

Remote Repositories: Back up code in the cloud
Collaboration Tools: Pull Requests, Issues, Projects
Social Coding: Explore and contribute to other developers' code
CI/CD: Automation with GitHub Actions

Create GitHub Account¶

Visit github.com
Click "Sign up"
Enter email, password, username
Complete email verification

2. SSH Key Setup (Recommended)¶

Using SSH keys means you don't have to enter your password every time.

Generate SSH Key¶

# Generate SSH key (use your GitHub account email)
ssh-keygen -t ed25519 -C "your_email@example.com"

# Use default settings (press Enter 3 times)

View SSH Key¶

# Display public key
cat ~/.ssh/id_ed25519.pub

Register SSH Key on GitHub¶

GitHub → Settings → SSH and GPG keys
Click "New SSH key"
Paste public key content
Click "Add SSH key"

Test Connection¶

ssh -T git@github.com

# Success message:
# Hi username! You've successfully authenticated...

3. Connecting Remote Repository¶

Push New Repository to GitHub¶

# 1. Create new repository on GitHub (empty repository)

# 2. Add remote repository from local
git remote add origin git@github.com:username/repository.git

# 3. First push
git push -u origin main

Clone Existing GitHub Repository¶

# SSH method (recommended)
git clone git@github.com:username/repository.git

# HTTPS method
git clone https://github.com/username/repository.git

# Clone with specific folder name
git clone git@github.com:username/repository.git my-folder

4. Managing Remote Repository¶

View Remote Repository¶

# List remote repositories
git remote

# Detailed information
git remote -v

Output example:

origin  git@github.com:username/repo.git (fetch)
origin  git@github.com:username/repo.git (push)

Add/Remove Remote Repository¶

# Add
git remote add origin URL

# Remove
git remote remove origin

# Change URL
git remote set-url origin new-URL

5. Push - Local → Remote¶

Upload local changes to remote repository.

# Basic push
git push origin branch-name

# Push main branch
git push origin main

# First push with -u option (set upstream)
git push -u origin main

# After upstream is set, simply
git push

Push Flow Diagram¶

Local                              Remote (GitHub)
┌─────────────┐                  ┌─────────────┐
│ Working Dir │                  │             │
│     ↓       │                  │             │
│ Staging     │     git push     │  Remote     │
│     ↓       │ ───────────────▶ │  Repository │
│ Local Repo  │                  │             │
└─────────────┘                  └─────────────┘

6. Pull - Remote → Local¶

Fetch changes from remote repository to local.

# Fetch remote changes + merge
git pull origin main

# If upstream is set
git pull

Fetch vs Pull¶

Command	Action
`git fetch`	Download remote changes only
`git pull`	fetch + merge (download + merge)

# Fetch, then check, then merge
git fetch origin
git log origin/main  # Check remote changes
git merge origin/main

# Process at once
git pull origin main

7. Working with Remote Branches¶

View Remote Branches¶

# All branches (local + remote)
git branch -a

# Remote branches only
git branch -r

Fetch Remote Branch¶

# Fetch remote branch to local
git switch -c feature origin/feature

# Or
git checkout -t origin/feature

Delete Remote Branch¶

# Delete remote branch
git push origin --delete branch-name

8. Practice Example: Complete Workflow¶

Upload New Project to GitHub¶

# 1. Create project locally
mkdir my-github-project
cd my-github-project
git init

# 2. Create files and commit
echo "# My GitHub Project" > README.md
echo "node_modules/" > .gitignore
git add .
git commit -m "initial commit"

# 3. Create new repository on GitHub (on web)
# - Click New repository
# - Enter name: my-github-project
# - Create empty repository (uncheck README)

# 4. Connect remote repository and push
git remote add origin git@github.com:username/my-github-project.git
git push -u origin main

# 5. Check on GitHub!

Collaboration Scenario¶

# Team member A: Make changes and push
echo "Feature A" >> features.txt
git add .
git commit -m "feat: add Feature A"
git push

# Team member B: Get latest code
git pull

# Team member B: Add own changes
echo "Feature B" >> features.txt
git add .
git commit -m "feat: add Feature B"
git push

When Conflict Occurs¶

# Attempt push - rejected
git push
# Output: rejected... fetch first

# Solution: pull first
git pull

# If conflict exists, resolve then
git add .
git commit -m "merge: resolve conflicts"
git push

Command Summary¶

Command	Description
`git remote -v`	View remote repository
`git remote add origin URL`	Add remote repository
`git clone URL`	Clone repository
`git push origin branch`	Local → remote
`git push -u origin branch`	Push + set upstream
`git pull`	Remote → local (fetch + merge)
`git fetch`	Download remote changes only

Next Steps¶

Let's learn collaboration methods using Fork, Pull Requests, and Issues in 05_GitHub_Collaboration.md!