Git author amend

How to change the author name and email in Git commit history

Git

There can be several use cases when you need to change author name and email in git commit history. Before sharing the solution that solved my issue, I would like to share the solution that prevents it.

How to use multiple git configuration

I am working for a customer that requires git commits are authored with my corporate email, while when I develop my side projects I want to use my GitHub nickname.

Usually I create in my user home folder, a folder named as the domain hosting the code. So for example I have folders:

Now if I want to use a different git config depending on the folder, I edit my ~/.gitconfig file with something like

[includeIf "gitdir:github.com/"]
  path = /Users/myuser/github.com/.gitconfig
[includeIf "gitdir:.config/"]
  path = /Users/myuser/github.com/.gitconfig
[includeIf "gitdir:source.my-customer.com/"]
  path = /Users/myuser/source.my-customer.com/.gitconfig
[github]
  user = my-github-nickname

Where my /Users/myuser/github.com/.gitconfig is something like

[user]
  name = my-github-nickname
  email = my-github-email@example.com
[pull]
  rebase = true
[init]
  defaultBranch = main

And the /Users/myuser/source.my-customer.com/.gitconfig is something similar.

How to change git history

I found this script here at stack overflow that uses git filter-branch

#!/bin/sh

git filter-branch --env-filter '
OLD_EMAIL="your-old-email@example.com"
CORRECT_NAME="Your Correct Name"
CORRECT_EMAIL="your-correct-email@example.com"
if [ "$GIT_COMMITTER_EMAIL" = "$OLD_EMAIL" ]
then
    export GIT_COMMITTER_NAME="$CORRECT_NAME"
    export GIT_COMMITTER_EMAIL="$CORRECT_EMAIL"
fi
if [ "$GIT_AUTHOR_EMAIL" = "$OLD_EMAIL" ]
then
    export GIT_AUTHOR_NAME="$CORRECT_NAME"
    export GIT_AUTHOR_EMAIL="$CORRECT_EMAIL"
fi
' --tag-name-filter cat -- --branches --tags

Just replace the variables OLD_EMAIL, CORRECT_NAME and CORRECT_EMAIL with the correct values, move to the repository folder and launch it. When it is done, probably you need to force the push

git push --force

Notice that if the commits need to be changed are also on a git tag, you need to fetch it and modify it locally, delete it remotely and then push it again.