That was the second time that I need to do that, so I'll merge my finds into this tip.
My method comes from severals sources throught internet, but mainly from these articles: www.martinahrer.at and stackoverflow.com.
The "cooking" commands to isolate a folder
Clone main repository:
git clone --no-hardlinks PATH_MAIN_REPO PATH_SECONDARY_REPO
Remove link from cloned repository:
git remote rm origin
Isolating desired folder:
git filter-branch --subdirectory-filter FOLDER_TO_BECOME_ROOT
Now all files from that folder are "moved" to root (something like that).
I don't know if its a bug or not, but GitExtensions shows 2 'master' branches, but only filtered is accessible.
Command to remove a folder from history
Remove folders from repository's history:
git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch FOLDER_THAT_BECAME_ROOT" --prune-empty -- --all
Cleanup empty entries:
git rev-list --remove-empty HEAD
git gc --prune=now --aggressive
After that, your repository won't have any entry of removed folder.
- 2 Apr 2012: Start of tip.
- 2 Apr 2012: Adding switches to avoid empty enties and cleaning history.