Ignoring Files

Use .gitignore to prevent Git from tracking files you don’t want committed, like dependencies, build output, or secrets.

Creating a .gitignore

Create a .gitignore file in your repository root:

# Dependencies
node_modules/

# Build output
dist/
build/

# Environment variables
.env
.env.local

# Logs
*.log

# OS files
.DS_Store
Thumbs.db

Git reads this file and skips anything that matches these patterns.

Pattern Syntax

• node_modules/ — ignores the directory
• *.log — ignores all .log files
• !important.log — negation: track this file even though *.log is ignored
• .env* — glob: matches .env, .env.local, .env.production

Directory vs File Patterns

Patterns ending with / match directories only. Without the trailing slash, Git matches both files and directories with that name.

logs/          # only matches directories named logs
logs           # matches both files and directories named logs

Global Gitignore

Set a global ignore for files across all repos:

git config --global core.excludesfile ~/.gitignore_global

Useful for OS-specific files (.DS_Store, Thumbs.db) without polluting each project.

Removing Tracked Files

If you added a file to .gitignore after it was already tracked, you need to untrack it manually:

git rm --cached filename.txt

The file stays in your working directory but Git stops tracking it.

Best Practices

• Add .gitignore before your first commit
• Commit your .gitignore so the team shares it
• Use a template for your tech stack (e.g., GitHub’s gitignore templates)
• Check what’s being tracked with git status regularly
• Review .gitignore periodically as projects evolve

Common Mistakes

• Forgetting that .gitignore only prevents tracking new files — already tracked files must be untracked with git rm --cached
• Using absolute paths instead of relative patterns
• Putting sensitive files in .gitignore instead of keeping them out of the repo entirely
• Ignoring .gitignore itself (which is valid, but rare)
• Not adding .env early and accidentally committing secrets