Questions tagged
git-rewrite-history
Rewriting the history of a Git repository, for example to edit old commits, remove unwanted data (e.g. private data or large files), rearrange file structure, fix commit metadata, etc.

There are many motivations for wanting to rewrite Git history:

  • Fixing up an old commit
  • Reducing repository size by removing large files previously checked into the repo - they still take up disk space even if removed from later commits
  • Removing sensitive data (passwords, credentials, etc) which you wouldn't want to share when sharing the repo, or even just moving a repo to an external hosting provider
  • Re-arranging or removing entire folders to reflect the splitting up of many sub-projects from one repo to many, or vice-versa

Git repositories store the whole of project history, and by design Git commits are immutable (their id changes completely if even a small part of their content or history is changed) - so how can you remove unwanted data stored deep in your repository’s past?

Tools for rewriting history

Changing history in a Git repository means rewriting all of the subsequent commit history from that point. There are several tools available to let you do this:

  • git commit --amend - for fixing the most recent commit you just made.
  • git rebase to rebase a branch's history, replaying it to look as though it was all based on a different (often newer) point in the repository's history. Used with the -i flag, can be used to interactively re-order history.
  • git filter-branch - an automated tool to rewrite many commits (on many branches) using one or more shell-scripts to make the alterations, which gives it great flexibility.
  • The BFG Repo-Cleaner - an alternative to git-filter-branch which achieves greater speed & usability by restricting itself to common use-cases around the task of removing unwanted data.

Sharing the rewritten history

If a repository has been shared prior to the rewrite, it's necessary to afterwards push the rewritten version to the main server with a --force or --mirror flag, and then request other users to re-clone the repository.