How do I remove an author from a git repository?

Question

If I create a Git repository and publish it publicly (e.g. on GitHub etc.), and I get a request from a contributor to the repository to remove or obscure their name for whatever reason, is there a way of doing so easily?

Basically, I have had such a request and may want to replace their name and e-mail address with something like "Anonymous Contributor" or maybe a SHA-1 hash of their e-mail address or something like that.

Answer 1

You can make the change in your local repository, git commit --amend the appropriate commit (where you added the name), and then git push --force to update github with your version of the repository.

The original commit with the contributor's name will still be available in the reflog (until it expires, but it would take a lot of effort to find it. If this is a concern, you can obliterate that specific commit from the reflog too -- see git help reflog for the syntax and how to find it in the list.

Answer 2

If you want to change more than one commit, check out the man page for

git filter-branch --env-filter

You can use git-filter-branch to change the content/meta of previous commits.

Note that since you're not dealing with a local branch (it's already been pushed to github), you have no way to remove the author from anyone who has already cloned your branch.

It's also generally bad practice to modify a branch which has already been published, since it can lead to confusion for people who are tracking the branch.

Answer 3

Jeff is quite right, the right track is git filter-branch. It expects a script that plays with the environment variables. For your use case, you probably want something like this:

git filter-branch --env-filter '
    if [ "$GIT_AUTHOR_NAME" = "Niko Schwarz" ]; then \
        export GIT_AUTHOR_NAME="Jon Doe" GIT_AUTHOR_EMAIL="[email protected]"; \
    fi
    '

You can test that it works like this:

$ cd /tmp
$ mkdir filter-branch && cd filter-branch
$ git init
Initialized empty Git repository in /private/tmp/filter-branch/.git/
$ 
$ touch hi && git add . && git commit -m bla
[master (root-commit) 081f7f5] bla
 0 files changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 hi
$ echo howdi >> hi && git commit -a -m bla
[master a466a18] bla
 1 files changed, 1 insertions(+), 0 deletions(-)
$ git log
commit a466a18e4dc48908f7ba52f8a373dab49a6cfee4
Author: Niko Schwarz <[email protected]>
Date:   Thu Aug 12 09:43:44 2010 +0200

    bla

commit 081f7f50921edc703b55c04654218fe95d09dc3c
Author: Niko Schwarz <[email protected]>
Date:   Thu Aug 12 09:43:34 2010 +0200

    bla
$ 
$ git filter-branch --env-filter '
> if [ "$GIT_AUTHOR_NAME" = "Niko Schwarz" ]; then \    
> export GIT_AUTHOR_NAME="Jon Doe" GIT_AUTHOR_EMAIL="[email protected]"; \
> fi
> '
Rewrite a466a18e4dc48908f7ba52f8a373dab49a6cfee4 (2/2)
Ref 'refs/heads/master' was rewritten
$ git log
commit 5f0dfc0dc9a325a3f3aaf4575369f15b0fb21fe9
Author: Jon Doe <[email protected]>
Date:   Thu Aug 12 09:43:44 2010 +0200

    bla

commit 3cf865fa0a43d2343b4fb6c679c12fc23f7c6015
Author: Jon Doe <[email protected]>
Date:   Thu Aug 12 09:43:34 2010 +0200

    bla

Please beware. There's no way to delete the author's name without invalidating all later commit hashes. That will make later merging a pain for people that have been using your repository.