Update all old email addresses in commits from all existing GitHub repos

git-update-all-emails.sh

# Requires `git filter-repo` https://github.com/newren/git-filter-repo

mkdir tmp && cd tmp

export USERNAME="github-username"
export TOKEN="github-token-with-repo-access"

curl -u "$USERNAME:$TOKEN" "https://api.github.com/search/repositories?q=user:$USERNAME" |
  grep -e 'ssh_url*' |
  cut -d \" -f 4 |
  xargs -L1 git clone

for d in ./*/ ; do
  pushd "$d"
  
  # ../my-mailmap
  # New Name <new@email.com> <old@email.com>
  # New Name <new@email.com> <different-old@email.com>
  # etc.
  git filter-repo --mailmap ../my-mailmap

  git remote add origin git@github.com:$USERNAME/${PWD##*/}.git
  git push --force origin master

  popd
done