Cloning and filtering file to new repo

commands.sh

git clone --no-hardlinks orig_repo new_repo
cd new_repo
git filter-branch --subdirectory-filter directory/containing/desired/file --prune-empty HEAD
git reset --hard
rm -rf .git/refs/original/
git remote rm origin
git update-ref -d refs/original/refs/heads/master
git reflog expire --expire=now --all
git gc --aggressive --prune=now
git repack -ad

curl -o git_cleanup.rb https://raw.github.com/gist/1428206/e1f16b1bee8928942f6a6286c87ce54775c20746/git_cleanup.rb
ruby git_cleanup.rb

#-------------------------------------------------------

git clone --no-hardlinks orig_repo other_repo
cd other_repo
git filter-branch --subdirectory-filter directory/containing/desired/file --prune-empty HEAD
git reset --hard
rm -rf .git/refs/original/
git remote rm origin
git update-ref -d refs/original/refs/heads/master
git reflog expire --expire=now --all
git gc --aggressive --prune=now
git repack -ad

curl -o git_cleanup.rb https://raw.github.com/gist/1428206/e1f16b1bee8928942f6a6286c87ce54775c20746/git_cleanup.rb
ruby git_cleanup.rb

#-------------------------------------------------------

cd new_repo
git remote add other_remote /path/to/other_repo
git fetch
git checkout -b other_branch other_remote/master
git rebase master

#------------------------------------------------------

git symbolic-ref HEAD refs/heads/newroot
git rm --cached -r .
git clean -f -d
git commit --allow-empty -m 'root commit'
git cherry-pick $(git rev-list --reverse master | head -1)
git rebase --onto newroot newroot master
git branch -d newroot

#------------------------------------------------------

git rebase -i <first commit SHA>

git_cleanup.rb

class GitCleanup
  DIRECTORY = File.dirname(__FILE__)
  KEEP_FILES = %w( analytics.rb ) << __FILE__
  FOR_REALZ = ENV['FOR_REALZ']

  def self.clean(directory=nil)
    directory ||= DIRECTORY
    relative_directory = directory.gsub(DIRECTORY, '')
    relative_directory.gsub!(/^\//, '')

    Dir.foreach(directory) do |item|
      next if item =~ /^\./ # ignore hidden files

      full_path = File.join(directory, item)
      relative_path = File.join(relative_directory, item)
      if ( KEEP_FILES & [item, full_path, relative_path] ).any?
        puts "Skipping #{relative_path}"
        next
      end

      if File.directory?(full_path)
        clean(full_path)
      else
        puts "Removing #{relative_path}"
        if FOR_REALZ
          `git filter-branch --index-filter 'git rm --ignore-unmatch #{relative_path}' --prune-empty HEAD`
          `git reset --hard`
          `rm -rf .git/refs/original/`
          `git reflog expire --expire=now --all`
          `git gc --aggressive --prune=now`
          `git repack -ad`
        end
      end
    end
  end
end

GitCleanup.clean

Resources:

• http://gbayer.com/development/moving-files-from-one-git-repository-to-another-preserving-history/
• http://stackoverflow.com/questions/359424/detach-subdirectory-into-separate-git-repository
• http://help.github.com/remove-sensitive-data/
• http://stackoverflow.com/questions/645450/git-how-to-insert-a-commit-as-the-first-shifting-all-the-others