Question on git-filter-branch

[Bill Lear <rael@zopyra.com>]

I'm testing out git-filter-branch, as I would like to use it to remove
proprietary information from our repository.

I created a test repo with "sensitive information" in a file 'A', some
other "plain" information, more sensitive stuff in file 'D', a subdirectory
of sensitive information (some of this added on a branch 'branch_1',
some added on master):

% ls -F sensitive
A  B  C  D  sensitive_stuff/

I then cloned this repo and tried the filter:

% git clone sensitive sensitive.clone
% cd sensitive.clone
% git filter-branch --index-filter 'git update-index --remove A' HEAD
Rewrite 5dd7d5f2d7d3a5f43c242188ac96294628267673 (7/7)
Ref 'refs/heads/master' was rewritten

These refs were rewritten:
% ls
A  B  C  D  sensitive_stuff

Ok, so it doesn't list the refs, so I do git status:

% git status
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       new file:   A
#

So, it seems to have done something to A, but I don't know what to do
next.

The man page says: "Now, you will get the rewritten history saved in
the branch newbranch (your current branch is left untouched)."  Well,
I don't see any new branch created:

% git branch -a
* master
  origin/HEAD
  origin/branch_1
  origin/master

Then next part of the man page counsels that "To set a commit ...",
but I'm not sure if that is what I want to do (I think it is).
However, I'm not sure what the 'graft-id' refers to, or if I'm
supposed to type in the command as specified, especially since this is
followed by this caution: "if the parent string is empty - which
happens when we are dealing with the initial commit - add graftcommit
as a parent".  Here, I'm unsure what graftcommit is, most especially
since the use of 'graft' first appears as 'graft-id'...

Could someone help, please?


Bill