Install & Configure

# ===== Install =====
# macOS (via Xcode CLT or Homebrew):
xcode-select --install
# or:
brew install git

# Ubuntu / Debian:
sudo apt update && sudo apt install -y git

# Fedora / RHEL:
sudo dnf install -y git

# Arch:
sudo pacman -S git

# Windows:
winget install Git.Git
# or download from https://git-scm.com (includes Git Bash)

# ===== Verify =====
git --version
# git version 2.45.x or newer

# ===== First-run config =====
git config --global user.name  'Alex Chen'
git config --global user.email 'alex@example.com'
git config --global init.defaultBranch main
git config --global pull.rebase false       # 'merge' style; switch to 'true' if you prefer rebase
git config --global core.autocrlf input     # macOS/Linux; on Windows use 'true'

# Editor preference:
git config --global core.editor 'code --wait'    # VS Code as the commit editor

# Useful default aliases:
git config --global alias.s 'status -sb'
git config --global alias.l 'log --oneline --graph --decorate -20'
git config --global alias.co 'checkout'
git config --global alias.br 'branch'

# ===== SSH key for GitHub / GitLab =====
ssh-keygen -t ed25519 -C 'alex@example.com'
# Press enter for default path; set a passphrase
cat ~/.ssh/id_ed25519.pub
# Paste into GitHub -> Settings -> SSH and GPG keys

# Test:
ssh -T git@github.com

# ===== Smoke test =====
mkdir hello-git && cd hello-git
git init
echo 'hello' > README.md
git add README.md
git commit -m 'initial commit'
git log --oneline

# ===== Verify everything =====
git config --get user.name
git config --get user.email
git config --get init.defaultBranch
git config --list --global

# ===== Patterns to internalise =====
# - Set user.name + user.email globally; per-repo overrides only when needed
# - SSH keys per machine; never share private keys
# - Aliases (s, l) save real time once the muscle memory kicks in
# - Use a credential helper for HTTPS (avoids retyping passwords)

# ===== Pitfalls =====
# - Using your work email on personal projects (commits inherit author)
# - core.autocrlf wrong for your platform -> noisy diffs
# - Forgetting to register the SSH key with the host -> 'Permission denied (publickey)'
# - Mixing global identity across employer + personal accounts (use directory-scoped includeIf)

# macOS:    brew install git
# Ubuntu:   apt install git
# Windows:  https://git-scm.com
git --version