Using .gitignore Files

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Table of contents

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1. What is .gitignore?
2. Basic syntax
3. Common patterns
4. Templates by language
5. Global .gitignore
6. Common problems
7. Best practices

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1 - What is .gitignore?

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The .gitignore file tells Git which files or folders not to track.

Why ignore files?

File type	Example	Reason
Dependencies	node_modules/	Too large, recreatable
Build	dist/, build/	Automatically generated
Secrets	.env, secrets.json	Security!
IDE	.vscode/, .idea/	Personal preferences
OS	.DS_Store, Thumbs.db	System files
Logs	*.log	Temporary
Cache	__pycache__/, .cache/	Recreatable

Create a .gitignore

# À la racine du projet
touch .gitignore

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2 - Basic syntax

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Simple rules

# Ceci est un commentaire

# Ignorer un fichier spécifique
secret.txt

# Ignorer un dossier
node_modules/

# Ignorer par extension
*.log
*.tmp

# Ignorer dans tous les sous-dossiers
**/temp/

# Négation (ne PAS ignorer)
!important.log

Pattern syntax

Pattern	Meaning	Example
file.txt	Exact file	file.txt
*.txt	All .txt files	readme.txt, notes.txt
folder/	Entire folder	folder/ and its contents
folder/*	Folder contents	Files in folder/
**/logs	logs anywhere	a/logs, a/b/logs
logs/**	Everything in logs	logs/a, logs/a/b
!file.txt	Exception	Do not ignore file.txt
[abc].txt	a.txt, b.txt, c.txt	Character class
file?.txt	file1.txt, fileA.txt	Any single character

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3 - Common patterns

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Secret configuration files

# Variables d'environnement
.env
.env.local
.env.*.local

# Fichiers de secrets
secrets.json
credentials.json
*.pem
*.key

Dependencies

# Node.js
node_modules/
package-lock.json  # Optionnel

# Python
venv/
__pycache__/
*.pyc

# PHP
vendor/

# Java
target/
*.jar

Build and output

# Build
dist/
build/
out/
*.min.js
*.min.css

# Coverage
coverage/
.nyc_output/

IDEs and editors

# VS Code
.vscode/
!.vscode/settings.json  # Garder les settings partagés

# JetBrains (IntelliJ, WebStorm, PyCharm)
.idea/
*.iml

# Vim
*.swp
*.swo

# Emacs
*~

Operating system

# macOS
.DS_Store
.AppleDouble
.LSOverride

# Windows
Thumbs.db
ehthumbs.db
Desktop.ini

# Linux
*~
.nfs*

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4 - Templates by language

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Node.js / JavaScript

# Dependencies
node_modules/

# Build
dist/
build/

# Environment
.env
.env.local
.env.*.local

# Logs
logs/
*.log
npm-debug.log*
yarn-debug.log*
yarn-error.log*

# IDE
.vscode/
.idea/

# OS
.DS_Store
Thumbs.db

# Testing
coverage/

# Cache
.cache/
.parcel-cache/

Python

# Byte-compiled
__pycache__/
*.py[cod]
*$py.class

# Virtual environment
venv/
ENV/
.venv/

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

# IDE
.idea/
.vscode/
*.swp

# Jupyter
.ipynb_checkpoints/

# Environment
.env

# Testing
.pytest_cache/
.coverage
htmlcov/

Java / Spring Boot

# Build
target/
build/

# IDE
.idea/
*.iml
.project
.classpath
.settings/

# Logs
*.log

# Maven
pom.xml.tag
pom.xml.releaseBackup
pom.xml.versionsBackup

# Gradle
.gradle/
gradle-app.setting
!gradle-wrapper.jar

Resource: gitignore.io

Automatically generate a .gitignore:

👉 https://www.toptal.com/developers/gitignore

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5 - Global .gitignore

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Global configuration

To ignore files across all your projects:

# Créer le fichier global
touch ~/.gitignore_global

# Configurer Git pour l'utiliser
git config --global core.excludesFile ~/.gitignore_global

Recommended content for ~/.gitignore_global

# macOS
.DS_Store
.AppleDouble
.LSOverride
._*

# Windows
Thumbs.db
ehthumbs.db
Desktop.ini

# IDE
.idea/
*.swp
*.swo
*~

# Logs généraux
*.log

When to use global vs local?

Type	Global	Local (project .gitignore)
OS files	✅	❌
Personal IDE preferences	✅	❌
Project dependencies	❌	✅
Project config	❌	✅
Build files	❌	✅

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6 - Common problems

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Problem 1: The file is already tracked

Symptom: You add a file to .gitignore but it is still tracked.

Cause: The file was added before the .gitignore.

Solution:

# Retirer du suivi (garder le fichier localement)
git rm --cached fichier.txt

# Pour un dossier
git rm -r --cached dossier/

# Commiter
git commit -m "chore: stop tracking fichier.txt"

Problem 2: Ignore everything except certain files

# Ignorer tout dans logs/
logs/*

# Sauf .gitkeep
!logs/.gitkeep

Problem 3: .gitignore doesn't work

Checks:

1. Is the file correctly named .gitignore (with the dot)?
2. Are there any trailing spaces at the end of lines?
3. Does the file have the right encoding (UTF-8)?

# Vérifier ce qui est ignoré
git check-ignore -v fichier.txt

# Voir tous les fichiers ignorés
git status --ignored

Problem 4: Secret committed by mistake

# 1. Ajouter au .gitignore
echo "secret.env" >> .gitignore

# 2. Retirer du suivi
git rm --cached secret.env

# 3. Commiter
git commit -m "security: remove secret from tracking"

# 4. IMPORTANT : Changer les secrets compromis !
# L'historique Git contient toujours le fichier

⚠️ To completely remove a secret from the history, use git filter-branch or BFG Repo-Cleaner.

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7 - Best practices

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✅ Do

1. Create the .gitignore at the start of the project
2. Use templates (gitignore.io)
3. Never commit secrets
4. Document unusual ignored files

❌ Avoid

1. Ignoring essential files (package.json, requirements.txt)
2. Ignoring the .gitignore itself
3. Ignoring shared config files (.editorconfig)

Recommended project structure

mon-projet/
├── .gitignore          # Ignorer fichiers du projet
├── .env.example        # Template pour .env (commité)
├── .env                # Variables réelles (ignoré)
├── package.json        # Commité
├── node_modules/       # Ignoré
├── dist/               # Ignoré
└── src/
    └── ...

Complete .gitignore example

# ===============================
# Dependencies
# ===============================
node_modules/
vendor/

# ===============================
# Build & Output
# ===============================
dist/
build/
*.min.js
*.min.css

# ===============================
# Environment & Secrets
# ===============================
.env
.env.local
.env.*.local
*.pem
secrets/

# ===============================
# IDE & Editors
# ===============================
.idea/
.vscode/
*.swp
*.swo

# ===============================
# OS Files
# ===============================
.DS_Store
Thumbs.db

# ===============================
# Logs & Cache
# ===============================
logs/
*.log
.cache/

# ===============================
# Testing
# ===============================
coverage/
.nyc_output/

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