foodir -- --all
-------------------------------------------------------

Thus you can, e.g., turn a library subdirectory into a repository of
its own.  Note the `--` that separates 'filter-branch' options from
revision options, and the `--all` to rewrite all branches and tags.

To set a commit (which typically is at the tip of another
history) to be the parent of the current initial commit, in
order to paste the other history behind the current history:

-------------------------------------------------------------------
git filter-branch --parent-filter 'sed "s/^\$/-p <graft-id>/"' HEAD
-------------------------------------------------------------------

(if the parent string is empty - which happens when we are dealing with
the initial commit - add graftcommit as a parent).  Note that this assumes
history with a single root (that is, no merge without common ancestors
happened).  If this is not the case, use:

--------------------------------------------------------------------------
git filter-branch --parent-filter \
	'test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>" || cat' HEAD
--------------------------------------------------------------------------

or even simpler:

-----------------------------------------------
git replace --graft $commit-id $graft-id
git filter-branch $graft-id..HEAD
-----------------------------------------------

To remove commits authored by "Darl McBribe" from the history:

------------------------------------------------------------------------------
git filter-branch --commit-filter '
	if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ];
	then
		skip_commit "$@";
	else
		git commit-tree "$@";
	fi' HEAD
------------------------------------------------------------------------------

The function 'skip_commit' is defined as follows:

--------------------------
skip_commit()
{
	shift;
	while [ -n "$1" ];
	do
		shift;
		map "$1";
		shift;
	done;
}
--------------------------

The shift magic first throws away the tree id and then the -p
parameters.  Note that this handles merges properly! In case Darl
committed a merge between P1 and P2, it will be propagated properly
and all children of the merge will become merge commits with P1,P2
as their parents instead of the merge commit.

*NOTE* the changes introduced by the commits, and which are not reverted
by subsequent commits, will still be in the rewritten branch. If you want
to throw out _changes_ together with the commits, you should use the
interactive mode of 'git rebase'.

You can rewrite the commit log messages using `--msg-filter`.  For
example, 'git svn-id' strings in a repository created by 'git svn' can
be removed this way:

-------------------------------------------------------
git filter-branch --msg-filter '
	sed -e "/^git-svn-id:/d"
'
-------------------------------------------------------

If you need to add 'Acked-by' lines to, say, the last 10 commits (none
of which is a merge), use this command:

--------------------------------------------------------
git filter-branch --msg-filter '
	cat &&
	echo "Acked-by: Bugs Bunny <bunny@bugzilla.org>"
' HEAD~10..HEAD
--------------------------------------------------------

The `--env-filter` option can be used to modify committer and/or author
identity.  For example, if you found out that your commits have the wrong
identity due to a misconfigured user.email, you can make a correction,
before publishing the project, like this:

--------------------------------------------------------
git filter-branch --env-filter '
	if test "$GIT_AUTHOR_EMAIL" = "root@localhost"
	then
		GIT_AUTHOR_EMAIL=john@example.com
	fi
	if test "$GIT_COMMITTER_EMAIL" = "root@localhost"
	then
		GIT_COMMITTER_EMAIL=john@example.com
	fi
' -- --all
--------------------------------------------------------

To restrict rewriting to only part of the history, specify a revision
range in addition to the new branch name.  The new branch name will
point to the top-most revision that a 'git rev-list' of this range
will print.

Consider