Optimize Your Git Commit History with git --fixup

In this blog post, I’ll introduce git –fixup, a valuable feature that aids in maintaining a clean commit history for your project. Whether you’re junior developer or someone with more experience, you’ve probably encountered situations where you’ve made multiple commits on a feature branch, only to discover a bug in a commit that you’d like to change. If the bug is in the most recent commit, you can use –amend to modify it. (Read more about amend here). However, if the commit you want to change is not the most recent one, you’ll need to make code changes, commit them, and then perform an interactive rebase to maintain a clean git history. This is where the git commit –fixup comes in handy. But before we explore the fixup command, let’s first understand how to achieve the same result without it, so you can appreciate its convenience.

Let’s consider the following commit history:

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* 0b2c830 (HEAD -> feature-A) Show error toastr message if user update is not successful
* 812d77a Change text in the Header.js
* c31bb1c Add notification toastr message when update of the user is successful
* 6e8f079 Change hint message on the Home Page
* 260a8a5 Add modal for changing user location address

Suppose we have a bug in the commit with SHA-1 260a8a5 (the last one), and we want to fix it. After resolving the bug, we make a new commit, resulting in the following history:

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* 2b10dde (HEAD -> feature-A) Fix save action in the modal for changing user location
* 0b2c830 Show error toastr message if user update is not successful
* 812d77a Change text in the Header.js
* c31bb1c Add notification toastr message when update of the user is successful
* 6e8f079 Change hint message on the Home Page
* 260a8a5 Add modal for changing user location address

To rewrite our git history and squash the commit that introduced the bug into the commit that fixed it, we need to perform an interactive rebase:

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$ git rebase --interactive HEAD~6

pick 260a8a5 Add modal for changing user location address
pick 6e8f079 Change hint message on the Home Page
pick c31bb1c Add notification toastr message when update of the user is successful
pick 812d77a Change text in the Header.js
pick 0b2c830 Show error toastr message if user update is not successful
pick 2b10dde Fix save action in the modal for changing user location

# Rebase 296c8b6..2b10dde onto 296c8b6 (6 commands)

Once the interactive rebase starts, we need to move the commit that fixes the bug bellow the commit that introduced the bug and change pick to fixup or simply use the letter f:

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pick 260a8a5 Add modal for changing user location address
fixup 2b10dde Fix save action in the modal for changing user location
pick 6e8f079 Change hint message on the Home Page
pick c31bb1c Add notification toastr message when update of the user is successful
pick 812d77a Change text in the Header.js
pick 0b2c830 Show error toastr message if user update is not successful

After completing these steps, simply close the editor, and git will handle the rest, providing a successful update message for the references.

Successfully rebased and updated refs/heads/feature-A.

You can admit that this whole process could take time and repeating all this is not nice, that’s why git has introduced git commit –fixup feature. Let’s see how using it is much easier than the above process.

The first thing to do once we fix a bug is to stage the changes and then commit them using the following command:

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$ git commit --fixup 260a8a5

After that our history will look like this:

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* f5b8829 (HEAD -> feature-A) fixup! Add modal for changing user location address
* e716f2d Show error toastr message if user update is not successful
* 98bc709 Change text in the Header.js
* e8da9ef Add notification toastr message when update of the user is successful
* e1f7672 Change hint message in the Home Page
* 260a8a5 Add modal for changing user location address

You can notice how git has added fixup! keyword just before the same commit message of the 260a8a5 commit, and this is how git will be able to move commits on his own once we execute rebase -i –autosquash commit-sha-1 command. commit-sha-1 represents one commit before the commit that we want to fix. So to squash commits we have to use interactive rebase with –autosquash option, and this will rewrite our history with squashing the original commit that introduced a bug into the commit that fixes the bug.

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$ git rebase --interactive --autosquash 260a8a5~1

When we execute this command we will get an interactive editor opened for us:

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pick 260a8a5 Add modal for changing user location address
fixup f5b8829 fixup! Add modal for changing user location address
pick e1f7672 Change hint message in the Home Page
pick e8da9ef Add notification toastr message when update of the user is successful
pick 98bc709 Change text in the Header.js

You can see how git has already rearranged commits for us and all we have to do next is to exit the interactive editor, git will do the rest for us, squashing commit that introduced a bug into the commit that fixed it, leaving us with a nice and clean git history.

This is really good practice if you’re working in the team that performs PR reviews, and you can imagine how your git commit history can look like when you add a bunch of new commits that contain small changes in order to fulfill all suggestions that your team members added after reviewing your PR.

I hope this blog post has helped you understand the git commit –fixed feature and I encourage you to utilize it in order to maintain a clean commit history. If you’re interested in learning more about git check out my ebook git-basics that I published on gumroad.