🎯 Git Basics¶

Git basics covers the fundamental commands for tracking changes in your project.

✅ Initializing a Repository¶

# Create a new repository in current directory
git init

# Creates a .git directory that tracks everything

This creates: - .git/ folder (hidden directory with all Git data) - A way to track all files in the current folder

✅ Git's Three States¶

Git has three main states:

Working Directory  →  Staging Area  →  Repository
    (modified)          (staged)         (committed)

Working Directory - Your actual files
Staging Area (Index) - Files prepared for commit
Repository - Committed snapshots (history)

✅ Checking Status¶

# See which files are changed, staged, or untracked
git status

Output shows: - Untracked files - New files Git doesn't know about - Modified files - Files changed but not staged - Staged changes - Files ready to be committed

✅ Staging Files¶

# Stage a specific file
git add filename.py

# Stage all files in current directory
git add .

# Stage all tracked files (skip untracked)
git add -u

# Interactive staging (select parts of files)
git add -i

# Patch mode (stage specific lines)
git add -p filename.py

✅ Committing Changes¶

# Commit staged changes with a message
git commit -m "Add user authentication feature"

# Commit all modified tracked files (skip git add)
git commit -am "Fix bug in login logic"

# Edit the commit message before committing
git commit

# Empty commit (useful for triggering CI)
git commit --allow-empty -m "Trigger build"

Good commit messages: - Start with a verb: Add, Fix, Update, Refactor - Keep the first line under 50 characters - Use imperative mood: "Add feature" not "Added feature" - Add details after a blank line if needed

✅ Viewing History¶

# Show commit history
git log

# Show compact history (one line per commit)
git log --oneline

# Show history with a graph
git log --graph --oneline

# Show last N commits
git log -3

# Show history for a specific file
git log filename.py

# Show changes in each commit
git log -p

# Show who changed what and when
git log --stat

✅ Viewing Differences¶

# Show differences between working directory and staging
git diff

# Show differences between staging and last commit
git diff --staged

# Show differences between working directory and last commit
git diff HEAD

# Show differences for a specific file
git diff filename.py

# Show differences between two commits
git diff commit1 commit2

✅ Ignoring Files¶

Create .gitignore to exclude files from tracking:

# Python
__pycache__/
*.pyc
*.pyo
.venv/
venv/

# IDE
.vscode/
.idea/
*.swp

# OS
.DS_Store
Thumbs.db

# Environment
.env
*.env

# Build
dist/
build/
*.egg-info/

✅ Removing and Moving Files¶

# Stage removal of a file (keeps working copy)
git rm filename.py

# Remove file from Git but keep locally
git rm --cached filename.py

# Move/rename a file (Git tracks the rename)
git mv old.py new.py

# These are equivalent to:
rm filename.py
git add filename.py

✅ Undoing Changes¶

# Unstage a file (keep changes)
git restore --staged filename.py

# Discard changes in working directory
git restore filename.py

# Undo last commit (keep changes)
git reset --soft HEAD~1

# Undo last commit (discard changes)
git reset --hard HEAD~1

# Revert a commit (create new commit that undoes it)
git revert commit-hash

✅ Best Practices¶

Commit often - Small, focused commits are easier to understand
Write clear messages - Future you (and others) will thank you
Stage selectively - Only commit related changes together
Ignore artifacts - Use .gitignore for generated files
Review before committing - git diff and git status

🔍 Key Takeaways¶

Git tracks changes in three states: working, staging, repository
git add moves changes to staging area
git commit saves staged changes as a snapshot
git status shows the current state
git log shows commit history
Use .gitignore to exclude files

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