Git Change Author

Rewrite commit author and committer identity for one email address.

What it Does

git-change-author rewrites history so commits that used an old author email use a new name and email. It updates both author and committer fields, then rewrites branches and tags.

Use it when a repository was committed under the wrong address and every matching commit should show the corrected identity.

Install

With Homebrew:

brew tap the-lupaxa-project/tap
brew trust the-lupaxa-project/tap
brew install git-change-author

Or run the script from a clone: ./src/git-change-author --help.

Quick Start

./src/git-change-author -S \
  -o old@example.com -e new@example.com -N "New Name"   # plan only — no changes
./src/git-change-author -n -L \
  -o old@example.com -e new@example.com -N "New Name"   # dry-run, local only
./src/git-change-author -y \
  -o old@example.com -e new@example.com -N "New Name"   # rewrite, then force-push

This rewrites history. Prefer --summary or -n first.

Default Behaviour

With the required identity flags and no mode flags, the script will:

1. Require a Git working tree (or --git-dir together with --work-tree)
2. Refuse to run if --old-email is not already in the history
3. Print an action plan
4. Ask you to type CHANGE before rewriting
5. Run git filter-branch so matching author and committer emails are replaced on all branches and tags
6. Force-push every branch and tag to origin when that remote exists

--local-only skips the push. --yes (and --force) skips the confirmation. --summary prints the plan and exits.

Common Options

Flag	Purpose
-o, --old-email EMAIL	Email address to replace (matched case-insensitively)
-e, --new-email EMAIL	Email address to write in its place
-N, --new-name NAME	Name to write for the new author and committer
-r, --remote NAME	Remote to force-push (default: origin)
-L, --local-only	Rewrite locally and do not touch the remote
-n, --dry-run	Simulate commands without changing anything
-S, --summary	Print a detailed plan based on all options and exit
-y, --yes	Skip the interactive CHANGE confirmation
-f, --force	Same as --yes
-d, --git-dir PATH	Path to the repository .git directory
-w, --work-tree PATH	Path to the working tree (use with --git-dir)
-V, --version	Print version and exit
-h, --help	Show help and exit

./src/git-change-author --help

Examples

Preview what a rewrite would do:

./src/git-change-author --summary \
  --old-email emmett.brown@example.com \
  --new-email marty.mcfly@example.com \
  --new-name "Marty McFly"

Rewrite the current repository and leave the remote alone:

./src/git-change-author --local-only --yes \
  --old-email emmett.brown@example.com \
  --new-email marty.mcfly@example.com \
  --new-name "Marty McFly"

Rewrite a repository that is not the current directory, then force-push origin:

./src/git-change-author \
  --git-dir /path/to/repo/.git \
  --work-tree /path/to/repo \
  --old-email emmett.brown@example.com \
  --new-email marty.mcfly@example.com \
  --new-name "Marty McFly" \
  --remote origin \
  --yes

Safety Notes

• --dry-run prints the action plan and simulates commands without asking for CHANGE.
• Real runs require typing CHANGE unless you pass -y / --yes (or -f / --force).
• --summary resolves the repository and prints the plan only — no rewrite is run.
• A missing old email fails before any rewrite. Commits that already use a different email are left unchanged.
• Force-push runs after a successful rewrite, unless you pass --local-only or the repository has no remote.
• Collaborators, forks, and clones must fetch the rewritten history and rebase local work onto it.