How to Use .gitignore to Exclude Files from Git Tracking

What is .gitignore?

A .gitignore file is a text file that tells Git which files or folders to ignore in a project. Ignored files are not tracked by Git, meaning they won’t be staged or committed. This is useful for files that are generated by your computer or build process, such as log files, compiled code, or dependency folders like node_modules.

Problem Scenario

When you run git status, you see a long list of untracked files that you don’t want to commit. These could be system files, editor configuration files, or build artifacts.

git status
On branch main
Untracked files:
  (use "git add <file>..." to include in what will be committed)
        .DS_Store
        logs/debug.log
        build/
        node_modules/

Committing these files would unnecessarily bloat the repository and could cause issues for other collaborators.

Solution

1. Create a .gitignore File

Create a file named .gitignore in the root directory of your Git repository.

You can create it using a text editor or a command line tool:

touch .gitignore

2. Add Patterns to .gitignore

Open the .gitignore file and add patterns for the files and directories you want to ignore. Each pattern should be on a new line.

# Ignore macOS system files
.DS_Store

# Ignore log files
logs/
*.log

# Ignore build output directory
build/

# Ignore dependency directories
node_modules/

• #: Lines starting with a hash are comments.
• logs/: Ignores the entire logs directory.
• *.log: Ignores any file with the .log extension (e.g., debug.log, error.log).
• build/: Ignores the build directory.
• node_modules/: Ignores the node_modules directory.

3. Commit the .gitignore File

The .gitignore file itself should be committed to the repository. This ensures that the same ignore rules are applied for all collaborators.

git add .gitignore
git commit -m "Add .gitignore file"

Now, when you run git status, the ignored files will no longer appear in the untracked files list.

Ignoring Already Tracked Files

What if you accidentally committed a file that should have been ignored? Simply adding the file to .gitignore won’t make Git stop tracking it.

You first need to tell Git to stop tracking the file using git rm --cached.

For example, to untrack the config.local file:

1. Add config.local to your .gitignore file.
2. Run the command:

   git rm --cached config.local
   

3. Commit the changes:

   git commit -m "Stop tracking config.local"
   

The --cached option removes the file from Git’s tracking, but it remains in your local directory.

Global .gitignore

You can also create a global .gitignore file for all your repositories on your system. This is useful for ignoring files specific to your operating system or editor.

1. Create a file, for example, ~/.gitignore_global.
2. Configure Git to use this file:

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

3. Add any global patterns to this file.

Conclusion

Using a .gitignore file is essential for keeping your repository clean and focused on the important source code. It prevents unnecessary files from being committed and shared. Many templates for different programming languages and frameworks are available online to get you started.