CODEWITHSUNDEEP
git
James Taylor
James Taylor

Reputation: 6258

Git filter branch from HEAD

I recently forked, committed, and made a pull request to a public repository where I am not a collaborator. My pull request hasn't been merged yet.

Looking through my commits, I realized I committed using the wrong author name and I want to fix it. I tried doing a rebase, which works great:

git rebase -i HEAD~7

Then I edited all the commits in question and, based on this answer, successfully changed the author of the commits.

git commit --amend --author "James <[email protected]>" --no-edit && \
git rebase --continue

Everything is good so far, but I noticed this changes the commit times to the current time. I want to preserve the previous timestamps. I tried following this answer, but filter-branch appears to have changed the hashes for the entire repository.

I probably shouldn't force push this. And even if I did, it probably would make it so that my pull request couldn't be merged. So, I tried looking for a way to run filter-branch on the last few commits on the branch, but I couldn't find anything. I tried:

git filter-branch --env-filter 'GIT_COMMITTER_DATE=$GIT_AUTHOR_DATE; export GIT_COMMITTER_DATE' HEAD~7

But that doesn't work. It exits with the error message:

Which ref do you want to rewrite?

What should I try to do? Is this possible?

Should I look into the --committer-date-is-author-date flag for the rebase? What does that do?

Upvotes: 3

Views: 896

Answers (2)

Matthieu Moy
Matthieu Moy

Reputation: 16577

Just pass the range of revisions you want to git filter-branch, like this:

git filter-branch --env-filter 'GIT_COMMITTER_DATE=$GIT_AUTHOR_DATE; export GIT_COMMITTER_DATE' HEAD~7..HEAD

Upvotes: 2

jpaugh
jpaugh

Reputation: 7035

I wouldn't worry about it. Observe that although the commit date changes, the author date is preserved.

If you think about it, this makes sense, given git's semantics: whenever the commit SHA changes, it's a new commit, and the commit-date should change, too.

However, the following should work:

$ git rebase --committer-date-is-author-date --onto origin/master master my-feature-branch

The above command will take all of the commits on my-feature-branch which are not in master, and rebase them atop origin/master. Because of the provided --committer-date-is-author-date, the author date will be duplicated to the commit date, but only if you do not use -i or --interactive.

This should still work even though you've rewritten your local history, although I haven't tried this.

Concerning the rebase command:

Here is the general form:

$ git rebase --onto NEW_BASE OLD_BASE SOME_BRANCH

If SOME_BRANCH is a branch from OLD_BASE, this will take all of the commits between OLD_BASE and SOME_BRANCH, and apply them to NEW_BASE instead of OLD_BASE.

Here is a more specific command, based on the few refs you provided:

$ git rebase --committer-date-is-author-date --onto origin/master HEAD~7 my-feature-branch

Upvotes: 1

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