How can you use git diff to see the changes between two different author’s commits?

Understanding how your team’s code has evolved over time is a fundamental part of effective software development, especially when collaborating on larger projects. One of the ways to do this is by using git diff to compare the changes between two different author’s commits. The git diff command shows the changes between two points in your Git repository.

Here’s a step-by-step guide:

Find the Commit Hashes

The first step is to identify the specific commits from the authors you want to compare. Each commit in Git is associated with a unique hash. You can use git log to see the commit history and find the hashes of the two commits you are interested in.

If you want to filter the log based on author name, you can use the --author option. For example, to see all commits by author “John Doe”, you’d use:

git log --author="John Doe"

This will output a log of all commits made by John Doe, which includes the commit hash, author, date, and commit message.

Use Git Diff with Commit Hashes

After you’ve identified the commit hashes, you can compare them using the git diff command followed by the two commit hashes. The syntax would be:

git diff <first-commit-hash> <second-commit-hash>

This will show you a line-by-line breakdown of the changes between these two commits.

Understanding Git Diff Output

The output of git diff might be a bit confusing if you’re not familiar with it. Here’s a brief explanation:

  • Lines that are added are marked with a + and are shown in green.
  • Lines that are removed are marked with a - and are shown in red.
  • Unchanged lines are shown in white.

Using Git Diff Between Two Authors

However, if you want to compare the cumulative changes of two different authors across the entire project history, it’s a bit more complex and there’s no direct Git command to achieve this. You might need to create separate branches for each author, cherry-pick their commits, and then compare the branches. This is more advanced usage of Git and is typically not necessary for everyday work.

Remember, git diff is a powerful command that can compare not just commits, but also branches and tags. As with any Git command, make sure you understand the implications of a command before you run it, as some Git commands can alter your repository’s history.