Script to take the email address of a commit author and change every commit by that author to the new author

rename_commit_author.sh

#!/bin/bash
set -euox pipefail
ORIG_AUTHOR=$1
NEW_AUTHOR=$2
for ORIG_HASH in $(git log --format=%h --author=$ORIG_AUTHOR); do
    ORIG_BRANCH=$(git rev-parse --abbrev-ref HEAD)
    CDATE=$(git show -s --format=%ci $ORIG_HASH)
    git checkout $ORIG_HASH
    GIT_AUTHOR_DATE=$CDATE GIT_COMMITTER_DATE=$CDATE git commit --amend --no-edit --author "$NEW_AUTHOR"
    NEW_HASH=$(git rev-parse --short HEAD)
    git replace $ORIG_HASH $NEW_HASH
    git filter-branch -f -- --all
    git replace -d $ORIG_HASH
    git checkout $ORIG_BRANCH
done