git-name-change

#!/bin/sh

# Clones a repo then changes the name and email address in entire history.

usage() {
    echo "usage: ${0##*/} REPO_URL OLD_EMAIL NEW_NAME NEW_EMAIL" >&2
    echo "clones the given repo, changing the name and email address in entire history" >&2
    exit 1
}

if echo "$*" | grep -Eq -- '--help\b|-h\b'; then
    usage
fi

REPO_URL="$1"
shift
OLD_EMAIL="$1"
shift
NEW_NAME="$1"
shift
NEW_EMAIL="$1"
shift

if [ -z "$REPO_URL" ] || [ -z "$OLD_EMAIL" ] || [ -z "$NEW_NAME" ] || [ -z "$NEW_EMAIL" ]; then
    usage
fi

REPO_DIR=rewrite.tmp

# Clone the repository
git clone "$REPO_URL" "$REPO_DIR"

# Change to the cloned repository
cd "$REPO_DIR" || exit 1

# Checkout all the remote branches as local tracking branches
git branch --list -r origin/* | cut -c10- | xargs -n1 git checkout

# Rewrite the history, use a system that will preserve the eol
# (or lack of in commit messages) - preferably Linux not OSX
git filter-branch -f --env-filter "

if [ \"\$GIT_COMMITTER_EMAIL\" = \"$OLD_EMAIL\" ]; then
    export GIT_COMMITTER_NAME=\"$NEW_NAME\"
    export GIT_COMMITTER_EMAIL=\"$NEW_EMAIL\"
fi

if [ \"\$GIT_AUTHOR_EMAIL\" = \"$OLD_EMAIL\" ]; then
    export GIT_AUTHOR_NAME=\"$NEW_NAME\"
    export GIT_AUTHOR_EMAIL=\"$NEW_EMAIL\"
fi

" --tag-name-filter cat -- --all --branches --tags