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How do you fix a bad merge, and replay your good commits onto a fixed merge?


Question

I accidentally committed an unwanted file (filename.orig while resolving a merge) to my repository several commits ago, without me noticing it until now. I want to completely delete the file from the repository history.

Is it possible to rewrite the change history such that filename.orig was never added to the repository in the first place?

2018/06/21
1
409
6/21/2018 6:57:50 PM

Accepted Answer

Please don't use this recipe if your situation is not the one described in the question. This recipe is for fixing a bad merge, and replaying your good commits onto a fixed merge.

Although filter-branch will do what you want, it is quite a complex command and I would probably choose to do this with git rebase. It's probably a personal preference. filter-branch can do it in a single, slightly more complex command, whereas the rebase solution is performing the equivalent logical operations one step at a time.

Try the following recipe:

# create and check out a temporary branch at the location of the bad merge
git checkout -b tmpfix <sha1-of-merge>

# remove the incorrectly added file
git rm somefile.orig

# commit the amended merge
git commit --amend

# go back to the master branch
git checkout master

# replant the master branch onto the corrected merge
git rebase tmpfix

# delete the temporary branch
git branch -d tmpfix

(Note that you don't actually need a temporary branch, you can do this with a 'detached HEAD', but you need to take a note of the commit id generated by the git commit --amend step to supply to the git rebase command rather than using the temporary branch name.)

2014/04/04
297
4/4/2014 12:20:19 AM


If you haven't committed anything since, just git rm the file and git commit --amend.

If you have

git filter-branch \
--index-filter 'git rm --cached --ignore-unmatch path/to/file/filename.orig' merge-point..HEAD

will go through each change from merge-point to HEAD, delete filename.orig and rewrite the change. Using --ignore-unmatch means the command won't fail if for some reason filename.orig is missing from a change. That's the recommended way from the Examples section in the git-filter-branch man page.

Note for Windows users: The file path must use forward slashes

2020/06/20

This is the best way:
http://github.com/guides/completely-remove-a-file-from-all-revisions

Just be sure to backup the copies of the files first.

EDIT

The edit by Neon got unfortunately rejected during review.
See Neons post below, it might contain useful information!


E.g. to remove all *.gz files accidentally committed into git repository:

$ du -sh .git ==> e.g. 100M
$ git filter-branch --index-filter 'git rm --cached --ignore-unmatch *.gz' HEAD
$ git push origin master --force
$ rm -rf .git/refs/original/
$ git reflog expire --expire=now --all
$ git gc --prune=now
$ git gc --aggressive --prune=now

That still didn't work for me? (I am currently at git version 1.7.6.1)

$ du -sh .git ==> e.g. 100M

Not sure why, since I only had ONE master branch. Anyways, I finally got my git repo truely cleaned up by pushing into a new empty and bare git repository, e.g.

$ git init --bare /path/to/newcleanrepo.git
$ git push /path/to/newcleanrepo.git master
$ du -sh /path/to/newcleanrepo.git ==> e.g. 5M 

(yes!)

Then I clone that to a new directory and moved over it's .git folder into this one. e.g.

$ mv .git ../large_dot_git
$ git clone /path/to/newcleanrepo.git ../tmpdir
$ mv ../tmpdir/.git .
$ du -sh .git ==> e.g. 5M 

(yeah! finally cleaned up!)

After verifying that all is well, then you can delete the ../large_dot_git and ../tmpdir directories (maybe in a couple weeks or month from now, just in case...)

2017/05/23

Rewriting Git history demands changing all the affected commit ids, and so everyone who's working on the project will need to delete their old copies of the repo, and do a fresh clone after you've cleaned the history. The more people it inconveniences, the more you need a good reason to do it - your superfluous file isn't really causing a problem, but if only you are working on the project, you might as well clean up the Git history if you want to!

To make it as easy as possible, I'd recommend using the BFG Repo-Cleaner, a simpler, faster alternative to git-filter-branch specifically designed for removing files from Git history. One way in which it makes your life easier here is that it actually handles all refs by default (all tags, branches, etc) but it's also 10 - 50x faster.

You should carefully follow the steps here: http://rtyley.github.com/bfg-repo-cleaner/#usage - but the core bit is just this: download the BFG jar (requires Java 6 or above) and run this command:

$ java -jar bfg.jar --delete-files filename.orig my-repo.git

Your entire repository history will be scanned, and any file named filename.orig (that's not in your latest commit) will be removed. This is considerably easier than using git-filter-branch to do the same thing!

Full disclosure: I'm the author of the BFG Repo-Cleaner.

2014/07/11

You should probably clone your repository first.

Remove your file from all branches history:
git filter-branch --tree-filter 'rm -f filename.orig' -- --all

Remove your file just from the current branch:
git filter-branch --tree-filter 'rm -f filename.orig' -- --HEAD    

Lastly you should run to remove empty commits:
git filter-branch -f --prune-empty -- --all
2016/06/10

The simplest way I found was suggested by leontalbot (as a comment), which is a post published by Anoopjohn. I think its worth its own space as an answer:

(I converted it to a bash script)

#!/bin/bash
if [[ $1 == "" ]]; then
    echo "Usage: $0 FILE_OR_DIR [remote]";
    echo "FILE_OR_DIR: the file or directory you want to remove from history"
    echo "if 'remote' argument is set, it will also push to remote repository."
    exit;
fi
FOLDERNAME_OR_FILENAME=$1;

#The important part starts here: ------------------------

git filter-branch -f --index-filter "git rm -rf --cached --ignore-unmatch $FOLDERNAME_OR_FILENAME" -- --all
rm -rf .git/refs/original/
git reflog expire --expire=now --all
git gc --prune=now
git gc --aggressive --prune=now

if [[ $2 == "remote" ]]; then
    git push --all --force
fi
echo "Done."

All credits goes to Annopjohn, and to leontalbot for pointing it out.

NOTE

Be aware that the script doesn't include validations, so be sure you don't make mistakes and that you have a backup in case something goes wrong. It worked for me, but it may not work in your situation. USE IT WITH CAUTION (follow the link if you want to know what is going on).

2016/05/17

Source: https://stackoverflow.com/questions/307828
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