GIT-FILTER-BRANCH(1) Git Manual GIT-FILTER-BRANCH(1)NAMEgit-filter-branch - Rewrite branches
SYNOPSISgit-filter-branch [--env-filter <command>] [--tree-filter <command>]
[--index-filter <command>] [--parent-filter <command>]
[--msg-filter <command>] [--commit-filter <command>]
[--tag-name-filter <command>] [--subdirectory-filter <directory>]
[--original <namespace>] [-d <directory>] [-f | --force]
[<rev-list options>...]
DESCRIPTION
Lets you rewrite git revision history by rewriting the branches
mentioned in the <rev-list options>, applying custom filters on each
revision. Those filters can modify each tree (e.g. removing a file or
running a perl rewrite on all files) or information about each commit.
Otherwise, all information (including original commit times or merge
information) will be preserved.
The command will only rewrite the positive refs mentioned in the
command line (e.g. if you pass a..b, only b will be rewritten). If you
specify no filters, the commits will be recommitted without any
changes, which would normally have no effect. Nevertheless, this may be
useful in the future for compensating for some git bugs or such,
therefore such a usage is permitted.
WARNING! The rewritten history will have different object names for all
the objects and will not converge with the original branch. You will
not be able to easily push and distribute the rewritten branch on top
of the original branch. Please do not use this command if you do not
know the full implications, and avoid using it anyway, if a simple
single commit would suffice to fix your problem.
Always verify that the rewritten version is correct: The original refs,
if different from the rewritten ones, will be stored in the namespace
refs/original/.
Note that since this operation is very I/O expensive, it might be a
good idea to redirect the temporary directory off-disk with the -d
option, e.g. on tmpfs. Reportedly the speedup is very noticeable.
Filters
The filters are applied in the order as listed below. The <command>
argument is always evaluated in the shell context using the eval
command (with the notable exception of the commit filter, for technical
reasons). Prior to that, the $GIT_COMMIT environment variable will be
set to contain the id of the commit being rewritten. Also,
GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, GIT_AUTHOR_DATE, GIT_COMMITTER_NAME,
GIT_COMMITTER_EMAIL, and GIT_COMMITTER_DATE are set according to the
current commit. The values of these variables after the filters have
run, are used for the new commit. If any evaluation of <command>
returns a non-zero exit status, the whole operation will be aborted.
A map function is available that takes an "original sha1 id" argument
and outputs a "rewritten sha1 id" if the commit has been already
rewritten, and "original sha1 id" otherwise; the map function can
return several ids on separate lines if your commit filter emitted
multiple commits.
OPTIONS--env-filter <command>
This filter may be used if you only need to modify the
environment in which the commit will be performed. Specifically,
you might want to rewrite the author/committer name/email/time
environment variables (see git-commit(1) for details). Do not
forget to re-export the variables.
--tree-filter <command>
This is the filter for rewriting the tree and its contents. The
argument is evaluated in shell with the working directory set to
the root of the checked out tree. The new tree is then used
as-is (new files are auto-added, disappeared files are
auto-removed - neither .gitignore files nor any other ignore
rules HAVE ANY EFFECT!).
--index-filter <command>
This is the filter for rewriting the index. It is similar to the
tree filter but does not check out the tree, which makes it much
faster. For hairy cases, see git-update-index(1).
--parent-filter <command>
This is the filter for rewriting the commit's parent list. It
will receive the parent string on stdin and shall output the new
parent string on stdout. The parent string is in a format
accepted by git-commit-tree(1): empty for the initial commit,
"-p parent" for a normal commit and "-p parent1 -p parent2 -p
parent3 ..." for a merge commit.
--msg-filter <command>
This is the filter for rewriting the commit messages. The
argument is evaluated in the shell with the original commit
message on standard input; its standard output is used as the
new commit message.
--commit-filter <command>
This is the filter for performing the commit. If this filter is
specified, it will be called instead of the git-commit-tree(1)
command, with arguments of the form "<TREE_ID> [-p
<PARENT_COMMIT_ID>]..." and the log message on stdin. The commit
id is expected on stdout.
As a special extension, the commit filter may emit multiple
commit ids; in that case, ancestors of the original commit will
have all of them as parents.
You can use the map convenience function in this filter, and
other convenience functions, too. For example, calling
skip_commit "$@" will leave out the current commit (but not its
changes! If you want that, use git-rebase(1) instead).
--tag-name-filter <command>
This is the filter for rewriting tag names. When passed, it will
be called for every tag ref that points to a rewritten object
(or to a tag object which points to a rewritten object). The
original tag name is passed via standard input, and the new tag
name is expected on standard output.
The original tags are not deleted, but can be overwritten; use
"--tag-name-filter cat" to simply update the tags. In this case,
be very careful and make sure you have the old tags backed up in
case the conversion has run afoul.
Note that there is currently no support for proper rewriting of
tag objects; in layman terms, if the tag has a message or
signature attached, the rewritten tag won't have it. Sorry. (It
is by definition impossible to preserve signatures at any rate.)
--subdirectory-filter <directory>
Only look at the history which touches the given subdirectory.
The result will contain that directory (and only that) as its
project root.
--original <namespace>
Use this option to set the namespace where the original commits
will be stored. The default value is refs/original.
-d <directory>
Use this option to set the path to the temporary directory used
for rewriting. When applying a tree filter, the command needs to
temporarily check out the tree to some directory, which may
consume considerable space in case of large projects. By default
it does this in the .git-rewrite/ directory but you can override
that choice by this parameter.
-f|--force
git filter-branch refuses to start with an existing temporary
directory or when there are already refs starting with
refs/original/, unless forced.
<rev-list-options>
When options are given after the new branch name, they will be
passed to git-rev-list(1). Only commits in the resulting output
will be filtered, although the filtered commits can still
reference parents which are outside of that set.
EXAMPLES
Suppose you want to remove a file (containing confidential information
or copyright violation) from all commits:
git filter-branch --tree-filter 'rm filename' HEAD
However, if the file is absent from the tree of some commit, a simple
rm filename will fail for that tree and commit. Thus you may instead
want to use rm -f filename as the script.
A significantly faster version:
git filter-branch --index-filter 'git update-index --remove filename' HEAD
Now, you will get the rewritten history saved in HEAD.
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 $GIT_COMMIT = <commit-id> && echo "-p <graft-id>" || cat' HEAD
or even simpler:
echo "$commit-id $graft-id" >> .git/info/grafts
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 "$1";
shift;
done;
}
The shift magic first throws away the tree id and then the -p
parameters. Note that this handles merges properly! In case Darl
committed a merge between P1 and P2, it will be propagated properly and
all children of the merge will become merge commits with P1,P2 as their
parents instead of the merge commit.
You can rewrite the commit log messages using --msg-filter. For
example, git-svn-id strings in a repository created by git-svn can be
removed this way:
git filter-branch --msg-filter '
sed -e "/^git-svn-id:/d"
ยด
To restrict rewriting to only part of the history, specify a revision
range in addition to the new branch name. The new branch name will
point to the top-most revision that a git rev-list of this range will
print.
NOTE the changes introduced by the commits, and which are not reverted
by subsequent commits, will still be in the rewritten branch. If you
want to throw out changes together with the commits, you should use the
interactive mode of git-rebase(1).
Consider this history:
D--E--F--G--H
/ /
A--B-----C
To rewrite only commits D,E,F,G,H, but leave A, B and C alone, use:
git filter-branch ... C..H
To rewrite commits E,F,G,H, use one of these:
git filter-branch ... C..H --not D
git filter-branch ... D..H --not C
To move the whole tree into a subdirectory, or remove it from there:
git filter-branch --index-filter \
'git ls-files -s | sed "s-\t-&newsubdir/-" |
GIT_INDEX_FILE=$GIT_INDEX_FILE.new \
git update-index --index-info &&
mv $GIT_INDEX_FILE.new $GIT_INDEX_FILE' HEAD
AUTHOR
Written by Petr "Pasky" Baudis <pasky@suse.cz>, and the git list
<git@vger.kernel.org>
DOCUMENTATION
Documentation by Petr Baudis and the git list.
GIT
Part of the git(7) suite
Git 1.5.5.2 10/21/2008 GIT-FILTER-BRANCH(1)
