Git & GitHub
From Zero to Pro

Copy# Before you start working — get latest changes from GitHub
git pull

# Do your work, then:
git add .
git commit -m "Describe what you did"
git push

Copy# Download a repo to your machine (one-time)
git clone https://github.com/USERNAME/REPO-NAME.git

Copy# See all branches (★ = where you are now)
git branch

# Create a new branch AND switch to it
git switch -c feature/add-github-page

# Switch to an existing branch
git switch main

# Delete a branch (after merging)
git branch -d feature/add-github-page

Copy# Step 1: Go to the branch you want to merge INTO
git switch main

# Step 2: Merge the feature branch into main
git merge feature/add-github-page

Copy# Python
__pycache__/
*.pyc
.env
venv/

# Node.js
node_modules/
dist/
.env.local

# macOS
.DS_Store

# Editors
.vscode/
.idea/

Copyname: CI                        # Name shown in GitHub UI

on:                              # WHEN to run this workflow
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  test:                          # Job name (can be anything)
    runs-on: ubuntu-latest      # Which OS to run on

    steps:
      - name: Checkout code
        uses: actions/checkout@v4   # Download your repo

      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.12"

      - name: Install dependencies
        run: pip install -r requirements.txt

      - name: Run tests
        run: pytest

Copyname: Lint Markdown

on: [push, pull_request]

jobs:
  markdownlint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Lint .md files
        uses: DavidAnson/markdownlint-cli2-action@v17
        with:
          globs: "**/*.md"

Copygit stash                      # save current changes away
git switch other-branch        # do your other work
git switch back-to-my-branch
git stash pop                  # restore saved changes

git stash list                 # see all stashes
git stash drop                 # delete the stash without restoring

Copy# Rebase your feature branch on top of latest main
git switch feature/my-feature
git rebase main

# Interactive rebase — squash, reorder, rename commits
git rebase -i HEAD~3   # edit last 3 commits

Copygit log --oneline --graph --all     # visual ASCII branch graph
git log --author="Your Name"          # filter by author
git log --since="2 weeks ago"         # filter by date
git log --grep="fix"                   # search commit messages
git log -p -- README.md               # history of one file

Copy# Tag a specific commit (e.g., version 1.0)
git tag -a v1.0 -m "First stable release"
git push origin v1.0

# List all tags
git tag

Copy# Set these once, use them forever
git config --global alias.st  "status"
git config --global alias.co  "switch"
git config --global alias.lg  "log --oneline --graph --all"

# Now you can type:
git st     # instead of git status
git lg     # instead of git log --oneline --graph --all

Copygit bisect start
git bisect bad              # current commit is broken
git bisect good v1.0        # v1.0 was working
# Git checks out a middle commit — test it, then:
git bisect good             # or: git bisect bad
# Repeat until Git finds the exact breaking commit
git bisect reset            # go back to HEAD when done