Undo a Git merge that hasn't been pushed yet
Within my master branch, I did a git merge some-other-branch locally, but never pushed the changes to origin master. I didn't mean to merge, so I'd like to undo it. When doing a git status after my merge, I was getting this message:
# On branch master
# Your branch is ahead of 'origin/master' by 4 commits.
Based upon some instructions I found, I tried running
git revert HEAD -m 1
but now I'm getting this message with git status:
# On branch master
# Your branch is ahead of 'origin/master' by 5 commits.
I don't want my branch to be ahead by any number of commits. How do I get back to that point?
Solution 1:
With git reflog check which commit is one prior the merge (git reflog will be a better option than git log). Then you can reset it using:
git reset --hard commit_sha
There's also another way:
git reset --hard HEAD~1
It will get you back 1 commit.
Be aware that any modified and uncommitted/unstashed files will be reset to their unmodified state. To keep them either stash changes away or see --merge option below.
As @Velmont suggested below in his answer, in this direct case using:
git reset --hard ORIG_HEAD
might yield better results, as it should preserve your changes. ORIG_HEAD will point to a commit directly before merge has occurred, so you don't have to hunt for it yourself.
A further tip is to use the --merge switch instead of --hard since it doesn't reset files unnecessarily:
git reset --merge ORIG_HEAD
--merge
Resets the index and updates the files in the working tree that are different between <commit> and HEAD, but keeps those which are different between the index and working tree (i.e. which have changes which have not been added).
Solution 2:
Assuming your local master was not ahead of origin/master, you should be able to do
git reset --hard origin/master
Then your local master branch should look identical to origin/master.
Solution 3:
See chapter 4 in the Git book and the original post by Linus Torvalds.
To undo a merge that was already pushed:
git revert -m 1 commit_hash
Be sure to revert the revert if you're committing the branch again, like Linus said.
Solution 4:
It is strange that the simplest command was missing. Most answers work, but undoing the merge you just did, this is the easy and safe way:
git reset --merge ORIG_HEAD
The ref ORIG_HEAD will point to the original commit from before the merge.
(The --merge option has nothing to do with the merge. It's just like git reset --hard ORIG_HEAD, but safer since it doesn't touch uncommitted changes.)