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Git: Getting back an amended commit

Today we are going to see how to recover a commit that was accidentally amended.

Let's say we are in the following situation:

$ git log --oneline
eb92db3c Second commit
2fddb4b3 First commit

We make some changes, stage them, and accidentally run git commit amend:

$ git commit --amend
[master c982fb5] Second commit (amended)
Date: Wed Dec 9 22:06:43 2015 +0100
1 file changed, 1 insertion(+)
create mode 100644 second.txt

The history is rewritten, so how to bring back the lost commit? If we had the git log output in our terminal that would be easy, we could just force some branch, say master, to point to the commit, in our case eb92db3c:

git branch -f master eb92db3

This would work but has two main problems:

The first problem can be addressed detaching HEAD temporarily:

git checkout --detach HEAD
git branch -f master eb92db3 
git checkout master

The second problem requires the use of the reflog, i.e. a registry that tracks all the movements of our branches. We can run:

$ git reflog master
c982fb5 master@{0}: commit (amend): Second commit (amended)
eb92db3 master@{1}: commit: Second commit
2fddb4b master@{2}: commit (initial): First commit

Here we can see that the last movement was a commit amend, so we just need to take the SHA1 of the previous commit and carry out the procedure above.