diff options
Diffstat (limited to 'Documentation/git-filter-branch.txt')
| -rw-r--r-- | Documentation/git-filter-branch.txt | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt new file mode 100644 index 0000000..8c43be6 --- /dev/null +++ b/Documentation/git-filter-branch.txt @@ -0,0 +1,278 @@ +git-filter-branch(1) +==================== + +NAME +---- +git-filter-branch - Rewrite branches + +SYNOPSIS +-------- +[verse] +'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>] + [-d <directory>] [-f | --force] [<rev-list options>...] + +DESCRIPTION +----------- +Lets you rewrite git revision history by creating a new branch from +your current branch, 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. + +*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 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. + + +Filters +~~~~~~~ + +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). +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. + +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 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 + 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 gitlink: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 + 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 + gitlink: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. + +--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. + +-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 + 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 gitlink: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 +------------------------------------------------------- + +A significantly faster version: + +-------------------------------------------------------------------------- +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). + +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 - therefore 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 $GIT_COMMIT = <commit-id> && echo "-p <graft-id>"' HEAD +-------------------------------------------------------------------------- + +or even simpler: + +----------------------------------------------- +echo "$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 + shift; + while [ -n "$1" ]; + do + shift; + echo "$1"; + shift; + done; + else + git commit-tree "$@"; + fi' HEAD +------------------------------------------------------------------------------ + +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 +to throw out _changes_ together with the commits, you should use the +interactive mode of gitlink: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 gitlink:git[7] suite |