Committing Changes¶
Commits are the heart of Git - they represent snapshots of your project at specific points in time. A good understanding of commits is essential for effective version control.
What is a Git Commit?¶
A commit is a permanent snapshot of your staged changes, stored in your repository's history. Each commit includes:
- 📸 Snapshot: The exact state of your files at that moment
- 👤 Author: Who made the changes (name and email)
- 📅 Timestamp: When the commit was created
- 💬 Message: Description of what changed and why
- 🔗 Parent: Reference to the previous commit(s)
- 🆔 Hash: Unique identifier (SHA-1)
The git commit Command¶
Basic Commit¶
Commit with Detailed Message¶
This opens your default editor for a multi-line commit message.Skip Staging for Tracked Files¶
The-a flag automatically stages all modified tracked files.
Writing Good Commit Messages¶
A good commit message follows this structure:
Short summary (50 characters or less)
More detailed explanation if needed. Wrap lines at 72 characters.
Explain what changed and why, not how.
- Bullet points are okay
- Use present tense: "Fix bug" not "Fixed bug"
- Reference issues: Fixes #123
Examples of Good Commit Messages¶
Short and clear:
git commit -m "Fix login button alignment"
git commit -m "Add user authentication system"
git commit -m "Update README with installation instructions"
Detailed commit message:
Add user profile page
- Create profile.html template
- Add CSS styling for profile cards
- Implement user data fetching
- Add responsive design for mobile devices
This addresses the user request for profile management
functionality mentioned in issue #45.
Message Conventions¶
Many projects follow conventional commit formats:
type(scope): description
Examples:
feat(auth): add password reset functionality
fix(ui): resolve button alignment issue
docs(readme): update installation instructions
style(css): improve header styling
refactor(api): simplify user data handling
test(auth): add login validation tests
Commit Best Practices¶
1. Make Atomic Commits¶
Each commit should represent one logical change:
# Good: One feature per commit
git add user-form.html
git commit -m "Add user registration form"
git add validation.js
git commit -m "Add form validation"
# Bad: Multiple unrelated changes
git add user-form.html validation.js footer.html
git commit -m "Various updates"
2. Commit Frequently¶
Don't wait too long between commits:
# Good workflow
git add feature.js
git commit -m "Implement basic feature structure"
# Continue working...
git add feature.js
git commit -m "Add error handling to feature"
# Continue working...
git add feature.js tests.js
git commit -m "Add tests for feature"
3. Use Present Tense¶
Write commit messages as if they complete the sentence "This commit will...":
# Good
git commit -m "Fix login validation bug"
git commit -m "Add user profile page"
git commit -m "Update dependencies"
# Avoid
git commit -m "Fixed login validation bug"
git commit -m "Added user profile page"
git commit -m "Updated dependencies"
Practical Examples¶
Example 1: Complete Workflow¶
# Start with a clean repository
git status
# Create and modify files
echo "<h1>Welcome</h1>" > index.html
echo "body { margin: 0; }" > styles.css
# Stage the files
git add index.html styles.css
# Check what's staged
git status
# Commit with a good message
git commit -m "Add basic HTML structure and CSS reset"
# Verify the commit
git log --oneline
Example 2: Multi-line Commit Message¶
# Stage your changes
git add .
# Open editor for detailed message
git commit
# In the editor, write:
# Add user authentication system
#
# - Implement login and logout functionality
# - Add password hashing with bcrypt
# - Create session management
# - Add input validation for forms
#
# This completes the authentication requirements
# from the project specification.
Viewing Commit History¶
Basic Log¶
Condensed View¶
Graphical View¶
Filter by Author¶
Filter by Date¶
Amending Commits¶
Fix the Last Commit Message¶
Add Files to Last Commit¶
# Stage the forgotten files
git add forgotten-file.txt
# Amend the last commit
git commit --amend --no-edit
Amending Published Commits
Only amend commits that haven't been pushed to a shared repository. Amending published commits can cause problems for collaborators.
Common Commit Scenarios¶
Scenario 1: Bug Fix¶
# Find and fix the bug
vim app.js
# Stage the fix
git add app.js
# Commit with clear message
git commit -m "Fix null pointer exception in user service"
Scenario 2: New Feature¶
# Implement the feature
git add new-feature.js new-feature.html new-feature.css
# Commit the complete feature
git commit -m "Add dark mode toggle functionality"
Scenario 3: Documentation Update¶
# Update documentation
git add README.md docs/
# Commit documentation changes
git commit -m "docs: update API documentation and README"
Troubleshooting Commits¶
Forgot to Add a File¶
# After committing, realize you forgot a file
git add forgotten-file.txt
git commit --amend --no-edit
Wrong Commit Message¶
Committed to Wrong Branch¶
# Create new branch from current commit
git branch correct-branch
# Reset current branch to previous commit
git reset --hard HEAD~1
# Switch to correct branch
git checkout correct-branch
Commit Hooks¶
You can automate checks before commits using Git hooks:
Pre-commit Hook Example¶
Create .git/hooks/pre-commit:
#!/bin/sh
# Run tests before committing
npm test
if [ $? -ne 0 ]; then
echo "Tests failed. Commit aborted."
exit 1
fi
Advanced Commit Features¶
Interactive Commits¶
Signed Commits¶
Empty Commits¶
# Create commit without changes (useful for triggering CI)
git commit --allow-empty -m "Trigger deployment"
Quick Reference¶
# Basic committing
git commit -m "message" # Commit staged changes
git commit -a -m "message" # Stage and commit tracked files
git commit --amend # Modify last commit
# Viewing commits
git log # Full commit history
git log --oneline # Condensed history
git show # Show last commit details
git show <commit-hash> # Show specific commit
# Commit information
git log --author="Name" # Filter by author
git log --since="1 week ago" # Filter by date
git log --grep="pattern" # Search commit messages
Next Steps¶
Great! You now understand how to create meaningful commits. Next, let's learn about working with files in Git, including renaming, moving, and deleting files.
Commit Mastery
You now know how to create clear, meaningful commits that will help you and your team understand the project's evolution over time!