Ignoring Local Changes to Files in Git

Ignoring Local Changes to Files in Git: The Power of --assume-unchanged

Introduction

As developers, we often work on projects where certain files, like composer.lock, are frequently updated locally but should not be committed to the repository. However, adding these files to .gitignore might not be the best approach, especially if they need to be tracked in the repository but ignored temporarily.

This is where Git’s --assume-unchanged flag comes in handy! In this blog post, we’ll explore what it does, when to use it, and how to revert the changes when needed.

What Does git update-index --assume-unchanged Do?

The command:

 git update-index --assume-unchanged composer.lock

Explanation:

• git update-index is a low-level Git command that modifies the index (staging area).
• --assume-unchanged tells Git to mark the file as "unchanged" in the working directory.

Effect of Running This Command:

• Git stops tracking modifications to the specified file (composer.lock in this case).
• If you edit composer.lock, Git won’t detect the changes and won’t include them in future commits.
• The file remains in the repository, but any local modifications stay untracked.

When Should You Use --assume-unchanged?

This feature is useful in the following scenarios:

• You have local environment-specific changes in a file (like composer.lock or .env) that you don’t want to commit but also don’t want to ignore permanently.
• You are working on a project where certain configuration files keep changing, but you don’t want those changes to show up in git status every time.
• You need a temporary workaround instead of modifying .gitignore or creating a separate local branch.

How to Check If a File Is Marked as --assume-unchanged?

To check whether a file has been marked with --assume-unchanged, use:

 git ls-files -v | grep '^h'

Files marked with an h are assumed to be unchanged.

Reverting the --assume-unchanged Status

If you later decide that you want Git to track changes to the file again, use:

 git update-index --no-assume-unchanged composer.lock

This command removes the "assume unchanged" flag, allowing Git to detect modifications as usual.

Important Considerations

• This does not remove the file from version control; it only affects local modifications.
• Other developers won’t be affected by this command—it’s purely a local setting.
• If you pull new changes from a remote repository that modify the file, you may experience conflicts.

Alternative Approach: .git/info/exclude

If you want to ignore a file only for yourself, without modifying .gitignore, you can add it to .git/info/exclude:

 echo 'composer.lock' >> .git/info/exclude

This works similarly to .gitignore but applies only to your local repository.

Conclusion

Using git update-index --assume-unchanged is a great way to temporarily ignore changes to tracked files in Git. It’s particularly useful for developers working on projects where some files change frequently but shouldn’t be committed every time.

Next time you’re tired of seeing local changes cluttering your git status, try this command and make your workflow cleaner!

Have You Used This Command Before?

If you have any tips or experiences using --assume-unchanged, share them in the comments! 🚀