completely remove a file from all revisions

You find a file that should never have been committed into the repo. Adding the file to a .gitignore list doesn't get rid of it for you, and you want the file to disappear from everything. (probably a good idea to back up repo before doing this)

method 1

git filter-branch --index-filter 'git rm --cached <file>' HEAD

method 2

git filter-branch -f --index-filter 'git update-index --remove filename' HEAD

• http://www.gitready.com/beginner/2009/03/06/ignoring-doesnt-remove-a-file.html
• http://github.com/guides/completely-remove-a-file-from-all-revisions