Git Commit - Save Changes

Complete guide to git commit command including commit messages, best practices, amending commits, commit history, and working with atomic commits for clean Git history.

git commit creates a permanent snapshot of staged changes in your repository. Writing good commit messages is crucial for maintainable projects.

Basic Commit

Example

# Commit staged changes with message git commit -m "Add user authentication module" # Output: # [main abc1234] Add user authentication module # 1 file changed, 45 insertions(+)

Interactive Commit (No Staging)

bash example

# Stage and commit in one command
git commit -a -m "Update database connection"
# Only works for modified files, not new files

Multi-line Commit Message

bash example

# Open editor for longer message
git commit

# In editor:
# Add user authentication system

# - Implements login/logout functionality
# - Uses JWT tokens for session management  
# - Password hashing with bcrypt
# - Unit tests for auth module

Commit Message Conventions

Poor Messages:

Example

git commit -m "fixed stuff" git commit -m "WIP" git commit -m "asdf" git commit -m "updated"

Good Messages:

git commit -m "Fix	Resolve memory leak in user service"
git commit -m "Feat	Add email verification on signup"
git commit -m "Docs	Update API documentation"
git commit -m "Refactor	Simplify authentication logic"

Commit Message Format

- feat	New feature
- fix	Bug fix
- docs	Documentation
- style	Code formatting
- refactor	Code restructuring
- test	Adding tests
- chore	Maintenance tasks

Amend Last Commit

bash example

# Forgot to include file or typo in message?
git add forgotten-file.js
git commit --amend

# Edit message in editor
# Replaces previous commit (local only!)

View Commits

bash example

# Last 5 commits
git log -5

# One-liner view
git log --oneline

# With graph (branches)
git log --graph --oneline --all

# Pretty format
git log --pretty=format:"%Cred%h %Creset%s %Cgreen(%cr) %C(bold blue)<%an>%Creset"

Atomic Commits

Good (atomic)

- Commit 1: Add login form HTML/CSS

- Commit 2: Implement login validation

- Commit 3: Add password hashing

- Commit 4: Add unit tests for login

Bad (bulk)

- Commit 1: "added login feature, updated db, fixed bugs, refactored auth"

Commit Lifecycle

Example

1. Make changes (working directory) 2. Stage changes (git add) 3. Commit (creates snapshot) 4. Push (upload to remote) 5. Done! Each commit is permanent, tracked, and reversible.

Best Practices

Commit frequently (multiple times per day)
Write clear messages explaining WHY
Keep commits focused on one feature/fix
Review changes before committing
Don't commit broken code
Include related changes only

Interview Q&A

Q1: What should a good commit message contain?

A: Clear subject (50 chars max) explaining what changed. Body explaining WHY the change (wrapped at 72 chars). Type prefix (feat, fix, docs) for categorization. Avoid vague messages like "fixed stuff". Good message: "Fix: Resolve infinite loop in data parser" explaining problem and solution.

Q2: What are atomic commits?

A: Atomic commits are focused snapshots addressing single feature, fix, or task. For example, separate commits for HTML changes, logic changes, and test changes. Opposite of bulk commits combining unrelated changes. Better for code review, debugging, and reverting specific changes.

Q3: How do you amend a commit?

A: Use git commit --amend to modify last commit. Add forgotten files with git add, then --amend replaces previous commit. Use to fix typos in messages or include missed files. Important: only amend commits not yet pushed to shared repository.

Q4: Difference between git commit -a and git commit -m?

A: git commit -m commits staged changes with message provided directly. git commit -a stages all tracked modified files then commits in one step. git commit -a doesn't stage new files, only modifications. Most workflows use staged git add then git commit -m for control.

Q5: Why write good commit messages?

A: Good messages help future developers (including yourself) understand why code changed. Essential for debugging: git log shows decisions. For code review: explains intent. For maintenance: helps new developers understand codebase. Teams investing in commit message quality have better maintainability long-term.

git commit creates a permanent snapshot of staged changes in your repository. Writing good commit messages is crucial for maintainable projects.

Basic Commit

Example

# Commit staged changes with message git commit -m "Add user authentication module" # Output: # [main abc1234] Add user authentication module # 1 file changed, 45 insertions(+)

Interactive Commit (No Staging)

bash example

# Stage and commit in one command
git commit -a -m "Update database connection"
# Only works for modified files, not new files

Multi-line Commit Message

bash example

# Open editor for longer message
git commit

# In editor:
# Add user authentication system

# - Implements login/logout functionality
# - Uses JWT tokens for session management  
# - Password hashing with bcrypt
# - Unit tests for auth module

Commit Message Conventions

Poor Messages:

Example

git commit -m "fixed stuff" git commit -m "WIP" git commit -m "asdf" git commit -m "updated"

Good Messages:

git commit -m "Fix	Resolve memory leak in user service"
git commit -m "Feat	Add email verification on signup"
git commit -m "Docs	Update API documentation"
git commit -m "Refactor	Simplify authentication logic"

Commit Message Format

- feat	New feature
- fix	Bug fix
- docs	Documentation
- style	Code formatting
- refactor	Code restructuring
- test	Adding tests
- chore	Maintenance tasks

Amend Last Commit

bash example

# Forgot to include file or typo in message?
git add forgotten-file.js
git commit --amend

# Edit message in editor
# Replaces previous commit (local only!)

View Commits

bash example

# Last 5 commits
git log -5

# One-liner view
git log --oneline

# With graph (branches)
git log --graph --oneline --all

# Pretty format
git log --pretty=format:"%Cred%h %Creset%s %Cgreen(%cr) %C(bold blue)<%an>%Creset"

Atomic Commits

Good (atomic)

- Commit 1: Add login form HTML/CSS

- Commit 2: Implement login validation

- Commit 3: Add password hashing

- Commit 4: Add unit tests for login

Bad (bulk)

- Commit 1: "added login feature, updated db, fixed bugs, refactored auth"

Commit Lifecycle

Example

1. Make changes (working directory) 2. Stage changes (git add) 3. Commit (creates snapshot) 4. Push (upload to remote) 5. Done! Each commit is permanent, tracked, and reversible.

Best Practices

Commit frequently (multiple times per day)
Write clear messages explaining WHY
Keep commits focused on one feature/fix
Review changes before committing
Don't commit broken code
Include related changes only

Interview Q&A

Q1: What should a good commit message contain?

Q2: What are atomic commits?

Q3: How do you amend a commit?

Q4: Difference between git commit -a and git commit -m?

Q5: Why write good commit messages?

Git Commit - Save Changes

Basic Commit

Interactive Commit (No Staging)

Multi-line Commit Message

Commit Message Conventions

Commit Message Format

Amend Last Commit

View Commits

Atomic Commits

Good (atomic)

Bad (bulk)

Commit Lifecycle

Best Practices

Interview Q&A

Continue learning this concept

Git Commit - Save Changes

Basic Commit

Interactive Commit (No Staging)

Multi-line Commit Message

Commit Message Conventions

Commit Message Format

Amend Last Commit

View Commits

Atomic Commits

Good (atomic)

Bad (bulk)

Commit Lifecycle

Best Practices

Interview Q&A

Continue learning this concept