Ignoring Files in Git

Git is a powerful version control system that helps you manage changes to your codebase. However, there are often files that you don’t want to track with Git, such as compiled binaries, log files, or operating system-specific files. In this tutorial, we’ll explore how to ignore certain files in Git.

Understanding .gitignore

The .gitignore file is a text file that tells Git which files or directories to ignore in a project. By adding patterns or specific file names to this file, you can prevent Git from tracking changes to those files.

To create a .gitignore file, simply create a new text file named .gitignore in the root directory of your Git repository. You can then add patterns or file names to the file, one per line.

Patterns and File Names

In the .gitignore file, you can use glob patterns to match files or directories. For example:

*.class will ignore all files with the .class extension
bin/ will ignore the entire bin directory
Hello.class will ignore a specific file named Hello.class

You can also use negation patterns by prefixing a pattern with an exclamation mark. For example:

!*.txt will ignore all files except those with the .txt extension

Ignoring Files Globally

If you want to ignore certain files globally, across all your Git repositories, you can create a global .gitignore file. To do this, run the following command:

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

This will tell Git to use the ~/.gitignore_global file as a global ignore file.

Ignoring Changed Files Temporarily

If you want to temporarily ignore changes to a tracked file, you can use the following command:

git update-index --assume-unchanged <file>

To revert this and start tracking changes again, use:

git update-index --no-assume-unchanged <file>

Removing Tracked Files from Git

If you’ve already committed a file to Git and want to remove it from the repository, you can use the following command:

git rm --cached <file>

This will remove the file from the Git index, but leave it in your working directory.

Example Use Case

Suppose you have a Java project with compiled .class files that you don’t want to track with Git. You can add the following line to your .gitignore file:

*.class

This will ignore all files with the .class extension in your repository.

In summary, ignoring files in Git is an important part of managing your codebase and keeping your repository clean. By using the .gitignore file and understanding glob patterns, you can easily ignore files that don’t need to be tracked.