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
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 "$@"'
+will leave out the current commit (but not its changes! If you want
+that, use gitlink:git-rebase[1] instead).
--tag-name-filter <command>::
This is the filter for rewriting tag names. When passed,
git filter-branch --index-filter 'git update-index --remove filename' HEAD
--------------------------------------------------------------------------
-Now, you will get the rewritten history saved in the branch 'newbranch'
-(your current branch is left untouched).
+Now, you will get the rewritten history saved in HEAD.
To set a commit (which typically is at the tip of another
history) to be the parent of the current initial commit, in
git filter-branch --parent-filter 'sed "s/^\$/-p <graft-id>/"' HEAD
-------------------------------------------------------------------
-(if the parent string is empty - therefore we are dealing with the
-initial commit - add graftcommit as a parent). Note that this assumes
+(if the parent string is empty - which happens when we are dealing with
+the initial commit - add graftcommit as a parent). Note that this assumes
history with a single root (that is, no merge without common ancestors
happened). If this is not the case, use:
git filter-branch --commit-filter '
if [ "$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_commits' 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.
+
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].
+
Consider this history:
------------------
projects / git.git / blobdiff