A Detailed Guide to Git Commits and Commit Message Guidelines

Q: What should I do if I realize I've left out a file after submitting?

Use git add to add the missing files, then run git commit --amend --no-edit to append them to the last commit. Note: You can only modify commits that haven't been pushed.

Q: How do I undo my last commit?

Use git reset --soft HEAD~1 to undo a commit but keep the changes in the staging area; use git reset --mixed HEAD~1 to undo a commit and return the changes to the working directory; use git reset --hard HEAD~1 to completely discard the changes.

Q: How do I view the details of a specific commit?

Use git show <commit-id> to view details of a specific commit, including commit metadata and file differences. Use git show without any parameters to view the most recent commit.

Committing is a core Git operation; each commit creates a unique version snapshot that records the complete state of the project at a given point in time.

1. Submitting Basic Concepts

(1) What Is a Commit?

A commit is the basic unit of Git version control and contains the following information:

Snapshot: The complete state of all tracked files at a given point in time
Metadata: Author information, submission date, submission details
Parent commit: A pointer to the previous commit (except for the first commit)
Unique Identifier: 40-character SHA-1 hash value

graph TB
    A[Workspace<br/>Working Directory] -->|git add| B[Buffer<br/>Staging Area]
    B -->|git commit| C[Repository<br/>Repository]
    C --> D[Generate a commit object<br/>Commit Object]
    D --> E[SHA-1Hash<br/>a1b2c3d4e5f6...]
    
    style A fill:#fff3cd
    style B fill:#d4edda
    style C fill:#c3e6cb
    style E fill:#cce5ff

(2) Submission Process

The complete submission process consists of three steps:

Modify File: Edit a file in the workspace
Stage Changes: Use git add to add changes to the staging area
Create a commit: Use git commit to commit the contents of the staging area to the repository

(3) The Purpose of Submission

Version History: Saves the complete state of the project at a specific point in time
Version History: You can view and revert to any version at any time
Collaboration Basics: Team members can collaborate based on commits
Change Notes: Describe the details of this modification in the submission notes.

2. Basic Submission Operations

(1) First Submission

▶ Example: Creating Your First Commit

BASH

# Initialize the repository
git init

# Create a File
echo "# My Project" > README.md

# View Status
git status
# Untracked files:
#   README.md

# Add to Stash
git add README.md

# Submit
git commit -m "Initial commit"

# Output：
# [main (root-commit) a1b2c3d] Initial commit
#  1 file changed, 1 insertion(+)
#  create mode 100644 README.md

(2) Regular Submissions

▶ Example: Standard Submission Process

BASH

# Edit File
echo "## Features" >> README.md

# View and Edit
git diff
# +## Features

# Add to Stash
git add README.md

# View Staging Status
git status
# Changes to be committed:
#   modified:   README.md

# Submit
git commit -m "Add features section"

# View commit history
git log --oneline
# a1b2c3d Add features section
# b2c3d4e Initial commit

(3) Bulk Submission

▶ Example: Batch Addition and Submission

BASH

# Create Multiple Files
touch file1.js file2.js file3.js

# Add All Files
git add .

# Or add specific types of files
git add *.js

# Submit
git commit -m "Add multiple JavaScript files"

# View Submission
git show
# commit a1b2c3d4e5f6...
# Author: Zhang San <zhangsan@example.com>
# Date:   Mon Jan 1 10:00:00 2026 +0800
#
#     Add multiple JavaScript files
#
# diff --git a/file1.js b/file1.js
# new file mode 100644
# index 0000000..e69de29

3. Submission Guidelines

(1) The Importance of Submitting Information

Good commit messages can:

Clearly explain changes: Help team members quickly understand what has been modified
Easy to Trace History: Makes it easy to find development records for specific features
Automation Tool Support: Supports automatic generation of change logs
Improve collaboration efficiency: Reduce communication costs

(2) Conventional Commits Standard

This is currently the most popular commit message convention, and the format is as follows:

TEXT

<type>(<scope>): <subject>

<body>

<footer>

Explanation of Each Section:

type (required): Submission type
scope (optional): Scope of impact
subject (required): Brief description
body (optional): Detailed description
footer (optional): Footer information

(3) Submission Type

Type	Description	Use Case
feat	New Feature	Add a new feature
fix	Bug Fix	Fix Program Error
docs	Document Edits	Update Document Content
style	Code formatting	Formatting changes that do not affect the meaning of the code
refactor	Refactoring	Code refactoring that neither adds features nor fixes bugs
perf	Performance Optimization	Improving Code Performance
test	Test	Add or modify test code
chore	Build/Tools	Changes to the build process or supporting tools
ci	CI Configuration	Modify the CI configuration file
revert	Revert	Commit before the revert

▶ Example: Standard Submission Information

BASH

# Single-line commit - New Features
git commit -m "feat: Add User Login Functionality"

# Single-line commit - BugFix
git commit -m "fix: Fix the login authentication error"

# Range-Based Submissions
git commit -m "feat(auth): AddJWTCertification Support"

# Multi-line commit
git commit -m "feat(user): Add a user registration feature" -m "Supports registration via email and phone number" -m "Add Form Validation and Error Messages"

# Submission with Footer（CloseIssue）
git commit -m "fix: Fixed a styling issue on the login page" -m "Closes #123"

# Use the editor to write a detailed commit message
git commit
# It will open in the editor，You can write a detailed commit message

(4) Best Practices for Submitting Information

Good commit messages:

TEXT

feat(auth): AddOAuth2.0Login Support

- SupportGoogle、GitHub、WeChat Third-Party Login
- Add Login State Persistence
- Enable Auto-RefreshTokenMechanism

Closes #456

Poor commit messages:

TEXT

update
fix bug
I made some changes.
WIP

4. Detailed Explanation of Submission Options

(1) Common Commit Options

Option	Description	Example
`-m`	Submit Information	`git commit -m "message"`
`-a`	Automatically stage tracked files	`git commit -a -m "message"`
`--amend`	Modify the last commit	`git commit --amend`
`--no-verify`	Skip commit hook	`git commit --no-verify -m "message"`
`--allow-empty`	Allow empty submissions	`git commit --allow-empty -m "message"`
`-s`	Add Signed-off-by	`git commit -s -m "message"`

▶ Example: Using the submission options

BASH

# Auto-check-in and commit（Applies only to tracked files）
echo "new content" >> README.md
git commit -a -m "Update README"

# Add a signature
git commit -s -m "feat: Add a New Feature"
# Will be added to the submitted information：
# Signed-off-by: Zhang San <zhangsan@example.com>

# Skippre-commitHook
git commit --no-verify -m "WIP: Save as Draft"

# View Submission Details
git show HEAD

(2) Submit Template

You can configure commit templates to ensure that team members follow a consistent format for commit messages.

BASH

# Create a commit template
cat > .git/commit-template << 'EOF'
# <type>(<scope>): <subject>
#
# typeAvailable values：
# feat, fix, docs, style, refactor, perf, test, chore
#
# subjectRules：
# - Using Imperative Sentences
# - Lowercase the first letter
# - Do not add a period at the end
EOF

# Configuring the Use of Templates
git config commit.template .git/commit-template

# Submit Using a Template
git commit
# It will open the editor，Display template content

5. Modify and Submit

(1) Modify the last commit

▶ Example: Modifying the commit message

BASH

# Edit the commit message for the last commit
git commit --amend -m "feat: Add User Login Functionality（After the correction）"

# Output：
# [main d4e5f6g] feat: Add User Login Functionality（After the correction）
#  Date: Mon Jan 1 10:00:00 2026 +0800
#  1 file changed, 1 insertion(+)

(2) Add files to the last commit

▶ Example: Adding Missing Files

BASH

# Suppose you realize after submitting that you've left out a file
git add forgotten-file.txt

# Add to the last commit，Do not modify the commit message
git commit --amend --no-edit

# Or add to and modify the commit message
git commit --amend -m "feat: Add user login functionality and related configurations"

(3) Modify the author information in the submission

▶ Example: Editing Author Information

BASH

# Change the author of the last commit
git commit --amend --author="Li Si <lisi@example.com>"

# Edit Submission Date
git commit --amend --date="2026-01-01 10:00:00"

(4) Important Notes on Modifying Submissions

graph TB
    A[Commit Changes] --> B{Has the commit been pushed??}
    B -->|Not pushed| C[Can be safely modified]
    B -->|Pushed| D[Forced push required]
    D --> E[May affect other developers]
    E --> F[Use with caution]
    
    style C fill:#d4edda
    style F fill:#f8d7da

⚠️ Important Warning:

Modify only commits that haven't been pushed
Modifications to a pushed commit require git push --force
Forced pushes can affect other developers, so communication in advance is necessary.
When working as a team, try to avoid modifying commits that have already been pushed

6. Submit Best Practices

(1) Atomic Commit

Each commit should contain only one logical change:

Best Practices:

BASH

# Submit1：Add Feature
git add feature.js
git commit -m "feat: Add User Login Functionality"

# Submit2：FixBug
git add fix.js
git commit -m "fix: Fix the login authentication error"

# Submit3：Update Documentation
git add README.md
git commit -m "docs: Update the Login Feature Documentation"

What Not to Do:

BASH

# A single commit containing multiple unrelated changes
git add .
git commit -m "Add Feature、FixBug、Update Documentation"

(2) Submission Frequency

Frequent commits: Take small, rapid steps; commit after completing each small feature
Complete commit: Each commit should represent a complete state.
Avoid half-finished work: Do not submit code that does not work

(3) Pre-submission Check

▶ Example: Pre-submission Checklist

BASH

# 1. View the content to be submitted
git status

# 2. View Specific Changes
git diff

# 3. View the contents of the staging area
git diff --staged

# 4. Submit after verifying that everything is correct
git commit -m "feat: Add a New Feature"

# 5. View Submission Results
git show

(4) Ignore file configuration

Use the .gitignore file to exclude files that do not need to be submitted:

TEXT

# .gitignoreExample

# Dependency Directory
node_modules/
vendor/

# Compilation Output
dist/
build/
*.o
*.class

# IDELayout
.vscode/
.idea/
*.swp

# Environment Configuration
.env
.env.local

# Log Files
*.log
logs/

# Operating System Files
.DS_Store
Thumbs.db

❓ FAQ

Q What should I do if I realize I've left out a file after submitting?

A Use git add to add the missing files, then run git commit --amend --no-edit to append them to the last commit. Note: You can only modify commits that haven't been pushed.

Q How do I undo my last commit?

A Use git reset --soft HEAD~1 to undo a commit but keep the changes in the staging area; use git reset --mixed HEAD~1 to undo a commit and return the changes to the working directory; use git reset --hard HEAD~1 to completely discard the changes.

Q In what language should the information be submitted?

A We recommend using English, since Git and most open-source projects use English. For internal team projects, you can also use Chinese, but be sure to maintain consistency.

Q How do I view the details of a specific commit?

A Use git show <commit-id> to view details of a specific commit, including commit metadata and file differences. Use git show without any parameters to view the most recent commit.

Q Why does it say "nothing to commit" when I try to commit?

A This means the staging area is empty. You need to first use git add to stage the changes, or use git commit -a to automatically stage changes to tracked files.

📖 Summary

Committing is a core Git operation that creates a snapshot of a version and records the project's history
Commit Process: Modify files → Stage changes → Create a commit
Write clear commit messages following the Conventional Commits guidelines
Use commit options to improve efficiency: -a to automatically stage changes, --amend to modify a commit
Modifying a commit that has already been pushed requires a force push, which may affect other developers.
Best Practices for Committing: Atomic commits, frequent commits, and pre-commit checks

📝 Exercises

Basic Exercise: Create a Git repository, add a README.md file, make your first commit with a proper commit message, and then view the commit history.
Advanced Problem: Simulate a scenario where you discover a missing file after submitting. Use the --amend option to append the file to your last commit, and verify the commit contents.
Challenge: Configure a commit template, create a template file that complies with the Conventional Commits guidelines, and use that template to make a commit, ensuring that the commit message follows the specified format.

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A Detailed Guide to Git Commits and Commit Message Guidelines

1. Submitting Basic Concepts

(1) What Is a Commit?

(2) Submission Process

(3) The Purpose of Submission

2. Basic Submission Operations

(1) First Submission

▶ Example: Creating Your First Commit

(2) Regular Submissions

▶ Example: Standard Submission Process

(3) Bulk Submission

▶ Example: Batch Addition and Submission

3. Submission Guidelines

(1) The Importance of Submitting Information

(2) Conventional Commits Standard

(3) Submission Type

▶ Example: Standard Submission Information

(4) Best Practices for Submitting Information

4. Detailed Explanation of Submission Options

(1) Common Commit Options

▶ Example: Using the submission options

(2) Submit Template

5. Modify and Submit

(1) Modify the last commit

▶ Example: Modifying the commit message

(2) Add files to the last commit

▶ Example: Adding Missing Files

(3) Modify the author information in the submission

▶ Example: Editing Author Information

(4) Important Notes on Modifying Submissions

6. Submit Best Practices

(1) Atomic Commit

(2) Submission Frequency

(3) Pre-submission Check

▶ Example: Pre-submission Checklist

(4) Ignore file configuration

❓ FAQ

📖 Summary

📝 Exercises

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