What does git diff –find-copies-harder do and when would it be useful?

The git diff command in Git is used to track the differences between the commits, work trees, files, etc. It’s a powerful tool for developers to see what has changed in their code. The --find-copies-harder option is an argument that can be passed to the git diff command to instruct it to work a bit harder to find copies.

Let’s delve deeper.

What does git diff --find-copies-harder do?

The --find-copies-harder option in git diff is used for detecting the cases when a file was copied and modified in the same commit.

In simpler terms, when you use the git diff command with the --find-copies-harder option, Git doesn’t just look for files that were renamed, but it also looks for files that were copied and then modified.

However, there is a caveat to this. The --find-copies-harder option makes Git search for the copies throughout the entire project’s history, even if the files were not modified in the commit you’re diffing against. This option causes the command to consume more time and processing power compared to the regular git diff operation.

When would it be useful?

The git diff --find-copies-harder can be especially useful in a number of scenarios:

  1. Refactoring and codebase restructuring: When you’re refactoring your codebase or restructuring it, you often need to duplicate a file and make slight modifications to it. In such cases, using the --find-copies-harder option can help you track these changes effectively.
  2. Tracking copied code: Sometimes in large codebases, it’s common to copy existing code and modify it for new features or bug fixes. Using git diff --find-copies-harder can help in tracking these copied and modified files.
  3. Code review and audits: During code reviews or audits, this option can help in finding the code that has been copied and then modified in the same commit.

It’s important to note that this option should be used sparingly, as it can be computationally expensive. It’s best used in situations where you suspect that code has been copied and slightly altered and you want to confirm your suspicions.


In conclusion, the git diff --find-copies-harder command can be a powerful tool when used in the right context. It gives you more thorough and complete information about changes made in your codebase, especially in terms of copied and slightly altered files. As with all powerful tools, it’s important to understand when to use it and keep in mind its potential impact on system resources.