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pdarragh/migrate_repo.sh

Created January 26, 2021 22:35
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  1. pdarragh created this gist Jan 26, 2021.
    54 changes: 54 additions & 0 deletions migrate_repo.sh
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    #!/usr/bin/env sh

    # I TAKE NO RESPONSIBILITY FOR YOUR CHOICE TO USE THIS SCRIPT.
    # It's probably a better idea to just read the commands and enter
    # them by hand one-by-one. But I've used this script and it works
    # for me, so here it is.

    # Migrates the commits from an old repository to a new one using
    # a rebase.
    #
    # NOTE: FAVORS COMMITS FROM THE OLD REPO WHEN THERE IS CONFLICT.
    # If you want to favor the new repo, use "theirs" as the
    # STRATEGY (fourth argument).
    # NOTE: RUN THIS SCRIPT FROM YOUR NEW REPOSITORY.

    OLD_REMOTE="$1"
    OLD_BRANCH="${2:-main}"
    NEW_BRANCH="${3:-main}"
    STRATEGY="${4:-theirs}"

    if [ -z "${OLD_REMOTE}" ] || [ -z "${OLD_BRANCH}" ] || [ -z "${NEW_BRANCH}" ]; then
    >&2 echo "usage: $0 OLD_REMOTE [OLD_BRANCH=$OLD_BRANCH] [NEW_BRANCH=$NEW_BRANCH] [STRATEGY=$STRATEGY]"
    >&2 echo ""
    >&2 echo "Example invocation:"
    >&2 echo " $0 git@github.com:username/repository.git master main"
    >&2 echo "This will rebase the commits from the master branch of the username/repository"
    >&2 echo "repository on top of the main branch of the current repository."
    >&2 echo ""
    >&2 echo "Call this script from your new repository."
    >&2 echo ""
    >&2 echo "Values given:"
    >&2 echo " OLD_REMOTE: ${OLD_REMOTE}"
    >&2 echo " OLD_BRANCH: ${OLD_BRANCH}"
    >&2 echo " NEW_BRANCH: ${NEW_BRANCH}"
    >&2 echo " STRATEGY: ${STRATEGY}"
    exit 1
    fi

    git remote add oldrepo "${OLD_REMOTE}"
    git remote update
    git checkout oldrepo/"${OLD_BRANCH}"
    git switch -c oldrepo-branch
    git pull --rebase -s recursive -X "${STRATEGY}" origin "${NEW_BRANCH}"
    git checkout "${NEW_BRANCH}"
    git merge --ff-only oldrepo-branch
    git remote remove oldrepo
    git branch -d oldrepo-branch

    echo ""
    echo "THE MIGRATION IS COMPLETE, BUT UNPUSHED."
    echo "To push the updated content, do:"
    echo " \$ git push origin ${NEW_BRANCH}"
    echo "To abort the migration and delete all unpushed commits, do:"
    echo " \$ git reset --hard origin"