unixorn/git-extra-commands

#!/usr/bin/env bash
# Author: Michael Demmer https://github.com/demmer
# License: MIT
# Original source: https://github.com/jut-io/git-scripts/blob/master/bin/git-change-author

prog=$(basename "$0")

force=
if [ "$1" == "-f" ] ; then
    force="-f"
    shift;
fi

old_email=$1; shift;
new_author=$1; shift;
new_email=$1; shift;

if test -z "$old_email" -o -z "$new_author" -o -z "$new_email" ; then
   echo "usage: $prog <old_email> <new_author> <new_email>"
   echo ""
   echo "example: $prog [-f] user@old.server.com \"User Name\" user2@new.server.com"
   exit 1
fi

echo "Rewriting commits for $old_email to $new_author <$new_email>"

export old_email
export new_author
export new_email

# shellcheck disable=SC2016,SC2048,SC2086
git filter-branch $force --env-filter '
an="$GIT_AUTHOR_NAME"
am="$GIT_AUTHOR_EMAIL"
cn="$GIT_COMMITTER_NAME"
cm="$GIT_COMMITTER_EMAIL"

if [ "$GIT_COMMITTER_EMAIL" = "$old_email" ]
then
    cn=$new_author
    cm=$new_email
fi
if [ "$GIT_AUTHOR_EMAIL" = "$old_email" ]
then
    an=$new_author
    am=$new_email
fi

export GIT_AUTHOR_NAME="$an"
export GIT_AUTHOR_EMAIL="$am"
export GIT_COMMITTER_NAME="$cn"
export GIT_COMMITTER_EMAIL="$cm"
' $*