Lets say, we are working on a feature, and you know, when we develop a feature, at first, things are messy, to say the least ;). So we added a bunch of commits. Now, your git log looks something similar to this.

* a81644b780 - oops! fix typo in the service file 
* 59046ea80b - lint and feature done!
* a130b381fd - init service method for the feature
* ca3764b5d8 - create api for the feature

Now, if you are like me, who want to leave things in a tidy manner, might feel a bit discomfort to see the last commit. Ideally the change made in the last commit, should have been inside the commit a130b381fd . But, it's parent commit 59046ea80b 's diff probably a huge one, and you are probably hesitating to undo all those changes. It's fine. We can still do this. git fixup with interactive rebase and autosquash come to the rescue.

The idea of git fixup is exactly what it means, to fixup some previous commit. We just need to grab the SHA of the commit that needs fixing.

We can get that from git log and the copy the specific SHA

Then we soft reset the last change. soft reset will preserve whatever change you made.

git reset --soft HEAD~1

Now, the last change is in staged area. We can commit, but this time we will do a little bit differently. We will fixup a previous commit. In our case, a130b381fd

git commit --fixup a130b381fd

Now, run the git log to see the change we made.

* 7b96ad9afa - fixup! init service method for the feature 
* 59046ea80b - lint and feature done!
* a130b381fd - init service method for the feature
* ca3764b5d8 - create api for the feature

See, we no longer have the unwanted commit? and instead we have a fixup! commit, which shadows the commit we want to fix?

We are half way there, we just need to merge the commit and its fixup. This can be done with the help of interactive rebase and autosquash.

git rebase -i --autosquash master

Now, run git log

* 59046ea80b - lint and feature done!
* a130b381fd - init service method for the feature
* ca3764b5d8 - create api for the feature

See, we have no longer the irritating commit? Thus, git fixup can help us to fix the commit, not just the latest commit with amend. This can be incredibly helpful when we are developing a big feature and want to leave the git history in a meaningful state.