SYNOPSIS
--------
[verse]
-'git-filter-branch' [--env-filter <command>] [--tree-filter <command>]
+'git 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>...]
+ [--] [<rev-list options>...]
DESCRIPTION
-----------
information) will be preserved.
The command will only rewrite the _positive_ refs mentioned in the
-command line (i.e. if you pass 'a..b', only 'b' will be rewritten).
+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.
+*NOTE*: This command honors `.git/info/grafts`. If you have any grafts
+defined, running this command will make them permanent.
+
*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.
+would suffice to fix your problem. (See the "RECOVERING FROM UPSTREAM
+REBASE" section in linkgit:git-rebase[1] for further information about
+rewriting published history.)
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 extensively I/O expensive, it might
+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.
~~~~~~~
The filters are applied in the order as listed below. The <command>
-argument is always evaluated in shell using the 'eval' command (with the
-notable exception of the commit filter, for technical reasons).
+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.
+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
-------
--env-filter <command>::
- This is the filter for modifying the environment in which
- the commit will be performed. Specifically, you might want
- to rewrite the author/committer name/email/time environment
+ 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 linkgit:git-commit[1] for details). Do not forget
to re-export the variables.
--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 linkgit:git-update-index[1].
+ faster. Frequently used with `git rm \--cached
+ \--ignore-unmatch ...`, see EXAMPLES below. For hairy
+ cases, see linkgit: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 linkgit:git-commit-tree[1]: empty for
+ the format described in linkgit: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.
--commit-filter <command>::
This is the filter for performing the commit.
If this filter is specified, it will be called instead of the
- linkgit:git-commit-tree[1] command, with arguments of the form
+ 'git-commit-tree' 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
+commit ids; in that case, the rewritten children 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 linkgit:git-rebase[1] instead).
+that, use 'git-rebase' instead).
++
+You can also use the 'git_commit_non_empty_tree "$@"' instead of
+'git commit-tree "$@"' if you don't wish to keep commits with a single parent
+and that makes no change to the tree.
--tag-name-filter <command>::
This is the filter for rewriting tag names. When passed,
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.)
+Nearly proper rewriting of tag objects is supported. If the tag has
+a message attached, a new tag object will be created with the same message,
+author, and timestamp. If the tag has a signature attached, the
+signature will be stripped. It is by definition impossible to preserve
+signatures. The reason this is "nearly" proper, is because ideally if
+the tag did not change (points to the same object, has the same name, etc.)
+it should retain any signature. That is not the case, signatures will always
+be removed, buyer beware. There is also no support for changing the
+author or timestamp (or the tag message for that matter). Tags which point
+to other tags will be rewritten to point to the underlying commit.
--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.
+--prune-empty::
+ Some kind of filters will generate empty commits, that left the tree
+ untouched. This switch allow git-filter-branch to ignore such
+ commits. Though, this switch only applies for commits that have one
+ and only one parent, it will hence keep merges points. Also, this
+ option is not compatible with the use of '--commit-filter'. Though you
+ just need to use the function 'git_commit_non_empty_tree "$@"' instead
+ of the 'git commit-tree "$@"' idiom in your commit filter to make that
+ happen.
+
--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
- temporary checkout the tree to some directory, which may consume
+ 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
+-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 linkgit: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.
+<rev-list options>...::
+ Arguments for 'git-rev-list'. All positive refs included by
+ these options are rewritten. You may also specify options
+ such as '--all', but you must use '--' to separate them from
+ the 'git-filter-branch' options.
Examples
git filter-branch --tree-filter 'rm filename' HEAD
-------------------------------------------------------
-A significantly faster version:
+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.
+
+Using `\--index-filter` with 'git-rm' yields a significantly faster
+version. Like with using `rm filename`, `git rm --cached filename`
+will fail if the file is absent from the tree of a commit. If you
+want to "completely forget" a file, it does not matter when it entered
+history, so we also add `\--ignore-unmatch`:
--------------------------------------------------------------------------
-git filter-branch --index-filter 'git update-index --remove filename' HEAD
+git filter-branch --index-filter 'git rm --cached --ignore-unmatch filename' HEAD
--------------------------------------------------------------------------
Now, you will get the rewritten history saved in HEAD.
+To rewrite the repository to look as if `foodir/` had been its project
+root, and discard all other history:
+
+-------------------------------------------------------
+git filter-branch --subdirectory-filter 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 \
- 'cat; test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>"' HEAD
+ 'test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>" || cat' HEAD
--------------------------------------------------------------------------
or even simpler:
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"
+'
+-------------------------------------------------------
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
+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 linkgit:git-rebase[1].
+interactive mode of 'git-rebase'.
Consider this history:
---------------------------------------------------------------
+
+Checklist for Shrinking a Repository
+------------------------------------
+
+git-filter-branch is often used to get rid of a subset of files,
+usually with some combination of `\--index-filter` and
+`\--subdirectory-filter`. People expect the resulting repository to
+be smaller than the original, but you need a few more steps to
+actually make it smaller, because git tries hard not to lose your
+objects until you tell it to. First make sure that:
+
+* You really removed all variants of a filename, if a blob was moved
+ over its lifetime. `git log \--name-only \--follow \--all \--
+ filename` can help you find renames.
+
+* You really filtered all refs: use `\--tag-name-filter cat \--
+ \--all` when calling git-filter-branch.
+
+Then there are two ways to get a smaller repository. A safer way is
+to clone, that keeps your original intact.
+
+* Clone it with `git clone +++file:///path/to/repo+++`. The clone
+ will not have the removed objects. See linkgit:git-clone[1]. (Note
+ that cloning with a plain path just hardlinks everything!)
+
+If you really don't want to clone it, for whatever reasons, check the
+following points instead (in this order). This is a very destructive
+approach, so *make a backup* or go back to cloning it. You have been
+warned.
+
+* Remove the original refs backed up by git-filter-branch: say `git
+ for-each-ref \--format="%(refname)" refs/original/ | xargs -n 1 git
+ update-ref -d`.
+
+* Expire all reflogs with `git reflog expire \--expire=now \--all`.
+
+* Garbage collect all unreferenced objects with `git gc \--prune=now`
+ (or if your git-gc is not new enough to support arguments to
+ `\--prune`, use `git repack -ad; git prune` instead).
+
+
Author
------
Written by Petr "Pasky" Baudis <pasky@suse.cz>,
GIT
---
-Part of the linkgit:git[7] suite
+Part of the linkgit:git[1] suite