DESCRIPTION
-----------
-Lets you rewrite git revision history by creating a new branch from
-your current branch, applying custom filters on each revision.
+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 takes the new branch name as a mandatory argument and
-the filters as optional arguments. 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.
+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).
+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
'refs/original/'.
Note that since this operation is extensively I/O expensive, it might
-be a good idea to redirect the temporary directory off-disk, e.g. on
-tmpfs. Reportedly the speedup is very noticeable.
+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
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. 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
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
- variables (see gitlink:git-commit[1] for details). Do not forget
+ variables (see linkgit:git-commit[1] for details). Do not forget
to re-export the variables.
--tree-filter <command>::
--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 gitlink:git-update-index[1].
+ faster. 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 gitlink:git-commit-tree[1]: empty for
+ a format accepted by 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
- gitlink:git-commit-tree[1] command, with arguments of the form
+ linkgit: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 linkgit:git-rebase[1] instead).
--tag-name-filter <command>::
This is the filter for rewriting tag names. When passed,
does this in the '.git-rewrite/' directory but you can override
that choice by this parameter.
--f\|--force::
+-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 gitlink:git-rev-list[1]. Only commits in the resulting
+ 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.
git filter-branch --index-filter 'git update-index --remove filename' HEAD
--------------------------------------------------------------------------
-Now, you will get the rewritten history saved in the branch 'newbranch'
-(your current branch is left untouched).
+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
git filter-branch --parent-filter 'sed "s/^\$/-p <graft-id>/"' HEAD
-------------------------------------------------------------------
-(if the parent string is empty - therefore we are dealing with the
-initial commit - add graftcommit as a parent). Note that this assumes
+(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 \
- 'cat; test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>"' HEAD
+ 'test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>" || cat' HEAD
--------------------------------------------------------------------------
or even simpler:
git filter-branch --commit-filter '
if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ];
then
- shift;
- while [ -n "$1" ];
- do
- shift;
- echo "$1";
- shift;
- done;
+ skip_commit "$@";
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 `--message-filter`. For
+example, `git-svn-id` strings in a repository created by `git-svn` can
+be removed this way:
+
+-------------------------------------------------------
+git filter-branch --message-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
will print.
-Note that the changes introduced by the commits, and not reverted by
-subsequent commits, will still be in the rewritten branch. If you want
+*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 gitlink:git-rebase[1].
+interactive mode of linkgit:git-rebase[1].
+
Consider this history:
GIT
---
-Part of the gitlink:git[7] suite
+Part of the linkgit:git[7] suite