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399 строки
15 KiB
Plaintext
git-filter-branch(1)
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====================
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NAME
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----
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git-filter-branch - Rewrite branches
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SYNOPSIS
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--------
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[verse]
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'git filter-branch' [--env-filter <command>] [--tree-filter <command>]
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[--index-filter <command>] [--parent-filter <command>]
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[--msg-filter <command>] [--commit-filter <command>]
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[--tag-name-filter <command>] [--subdirectory-filter <directory>]
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[--original <namespace>] [-d <directory>] [-f | --force]
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[--] [<rev-list options>...]
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DESCRIPTION
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-----------
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Lets you rewrite git revision history by rewriting the branches mentioned
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in the <rev-list options>, applying custom filters on each revision.
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Those filters can modify each tree (e.g. removing a file or running
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a perl rewrite on all files) or information about each commit.
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Otherwise, all information (including original commit times or merge
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information) will be preserved.
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The command will only rewrite the _positive_ refs mentioned in the
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command line (e.g. if you pass 'a..b', only 'b' will be rewritten).
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If you specify no filters, the commits will be recommitted without any
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changes, which would normally have no effect. Nevertheless, this may be
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useful in the future for compensating for some git bugs or such,
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therefore such a usage is permitted.
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*NOTE*: This command honors `.git/info/grafts`. If you have any grafts
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defined, running this command will make them permanent.
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*WARNING*! The rewritten history will have different object names for all
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the objects and will not converge with the original branch. You will not
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be able to easily push and distribute the rewritten branch on top of the
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original branch. Please do not use this command if you do not know the
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full implications, and avoid using it anyway, if a simple single commit
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would suffice to fix your problem. (See the "RECOVERING FROM UPSTREAM
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REBASE" section in linkgit:git-rebase[1] for further information about
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rewriting published history.)
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Always verify that the rewritten version is correct: The original refs,
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if different from the rewritten ones, will be stored in the namespace
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'refs/original/'.
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Note that since this operation is very I/O expensive, it might
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be a good idea to redirect the temporary directory off-disk with the
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'-d' option, e.g. on tmpfs. Reportedly the speedup is very noticeable.
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Filters
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~~~~~~~
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The filters are applied in the order as listed below. The <command>
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argument is always evaluated in the shell context using the 'eval' command
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(with the notable exception of the commit filter, for technical reasons).
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Prior to that, the $GIT_COMMIT environment variable will be set to contain
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the id of the commit being rewritten. Also, GIT_AUTHOR_NAME,
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GIT_AUTHOR_EMAIL, GIT_AUTHOR_DATE, GIT_COMMITTER_NAME, GIT_COMMITTER_EMAIL,
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and GIT_COMMITTER_DATE are set according to the current commit. The values
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of these variables after the filters have run, are used for the new commit.
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If any evaluation of <command> returns a non-zero exit status, the whole
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operation will be aborted.
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A 'map' function is available that takes an "original sha1 id" argument
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and outputs a "rewritten sha1 id" if the commit has been already
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rewritten, and "original sha1 id" otherwise; the 'map' function can
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return several ids on separate lines if your commit filter emitted
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multiple commits.
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OPTIONS
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-------
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--env-filter <command>::
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This filter may be used if you only need to modify the environment
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in which the commit will be performed. Specifically, you might
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want to rewrite the author/committer name/email/time environment
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variables (see linkgit:git-commit[1] for details). Do not forget
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to re-export the variables.
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--tree-filter <command>::
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This is the filter for rewriting the tree and its contents.
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The argument is evaluated in shell with the working
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directory set to the root of the checked out tree. The new tree
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is then used as-is (new files are auto-added, disappeared files
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are auto-removed - neither .gitignore files nor any other ignore
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rules *HAVE ANY EFFECT*!).
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--index-filter <command>::
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This is the filter for rewriting the index. It is similar to the
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tree filter but does not check out the tree, which makes it much
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faster. Frequently used with `git rm \--cached
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\--ignore-unmatch ...`, see EXAMPLES below. For hairy
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cases, see linkgit:git-update-index[1].
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--parent-filter <command>::
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This is the filter for rewriting the commit's parent list.
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It will receive the parent string on stdin and shall output
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the new parent string on stdout. The parent string is in
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the format described in linkgit:git-commit-tree[1]: empty for
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the initial commit, "-p parent" for a normal commit and
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"-p parent1 -p parent2 -p parent3 ..." for a merge commit.
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--msg-filter <command>::
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This is the filter for rewriting the commit messages.
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The argument is evaluated in the shell with the original
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commit message on standard input; its standard output is
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used as the new commit message.
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--commit-filter <command>::
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This is the filter for performing the commit.
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If this filter is specified, it will be called instead of the
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'git-commit-tree' command, with arguments of the form
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"<TREE_ID> [-p <PARENT_COMMIT_ID>]..." and the log message on
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stdin. The commit id is expected on stdout.
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+
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As a special extension, the commit filter may emit multiple
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commit ids; in that case, the rewritten children of the original commit will
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have all of them as parents.
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+
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You can use the 'map' convenience function in this filter, and other
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convenience functions, too. For example, calling 'skip_commit "$@"'
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will leave out the current commit (but not its changes! If you want
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that, use 'git-rebase' instead).
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+
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You can also use the 'git_commit_non_empty_tree "$@"' instead of
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'git commit-tree "$@"' if you don't wish to keep commits with a single parent
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and that makes no change to the tree.
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--tag-name-filter <command>::
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This is the filter for rewriting tag names. When passed,
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it will be called for every tag ref that points to a rewritten
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object (or to a tag object which points to a rewritten object).
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The original tag name is passed via standard input, and the new
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tag name is expected on standard output.
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+
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The original tags are not deleted, but can be overwritten;
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use "--tag-name-filter cat" to simply update the tags. In this
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case, be very careful and make sure you have the old tags
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backed up in case the conversion has run afoul.
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+
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Nearly proper rewriting of tag objects is supported. If the tag has
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a message attached, a new tag object will be created with the same message,
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author, and timestamp. If the tag has a signature attached, the
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signature will be stripped. It is by definition impossible to preserve
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signatures. The reason this is "nearly" proper, is because ideally if
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the tag did not change (points to the same object, has the same name, etc.)
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it should retain any signature. That is not the case, signatures will always
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be removed, buyer beware. There is also no support for changing the
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author or timestamp (or the tag message for that matter). Tags which point
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to other tags will be rewritten to point to the underlying commit.
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--subdirectory-filter <directory>::
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Only look at the history which touches the given subdirectory.
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The result will contain that directory (and only that) as its
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project root.
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--prune-empty::
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Some kind of filters will generate empty commits, that left the tree
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untouched. This switch allow git-filter-branch to ignore such
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commits. Though, this switch only applies for commits that have one
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and only one parent, it will hence keep merges points. Also, this
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option is not compatible with the use of '--commit-filter'. Though you
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just need to use the function 'git_commit_non_empty_tree "$@"' instead
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of the 'git commit-tree "$@"' idiom in your commit filter to make that
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happen.
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--original <namespace>::
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Use this option to set the namespace where the original commits
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will be stored. The default value is 'refs/original'.
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-d <directory>::
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Use this option to set the path to the temporary directory used for
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rewriting. When applying a tree filter, the command needs to
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temporarily check out the tree to some directory, which may consume
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considerable space in case of large projects. By default it
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does this in the '.git-rewrite/' directory but you can override
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that choice by this parameter.
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-f::
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--force::
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'git-filter-branch' refuses to start with an existing temporary
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directory or when there are already refs starting with
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'refs/original/', unless forced.
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<rev-list options>...::
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Arguments for 'git-rev-list'. All positive refs included by
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these options are rewritten. You may also specify options
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such as '--all', but you must use '--' to separate them from
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the 'git-filter-branch' options.
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Examples
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--------
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Suppose you want to remove a file (containing confidential information
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or copyright violation) from all commits:
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-------------------------------------------------------
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git filter-branch --tree-filter 'rm filename' HEAD
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-------------------------------------------------------
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However, if the file is absent from the tree of some commit,
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a simple `rm filename` will fail for that tree and commit.
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Thus you may instead want to use `rm -f filename` as the script.
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Using `\--index-filter` with 'git-rm' yields a significantly faster
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version. Like with using `rm filename`, `git rm --cached filename`
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will fail if the file is absent from the tree of a commit. If you
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want to "completely forget" a file, it does not matter when it entered
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history, so we also add `\--ignore-unmatch`:
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--------------------------------------------------------------------------
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git filter-branch --index-filter 'git rm --cached --ignore-unmatch filename' HEAD
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--------------------------------------------------------------------------
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Now, you will get the rewritten history saved in HEAD.
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To rewrite the repository to look as if `foodir/` had been its project
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root, and discard all other history:
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-------------------------------------------------------
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git filter-branch --subdirectory-filter foodir -- --all
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-------------------------------------------------------
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Thus you can, e.g., turn a library subdirectory into a repository of
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its own. Note the `\--` that separates 'filter-branch' options from
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revision options, and the `\--all` to rewrite all branches and tags.
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To set a commit (which typically is at the tip of another
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history) to be the parent of the current initial commit, in
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order to paste the other history behind the current history:
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-------------------------------------------------------------------
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git filter-branch --parent-filter 'sed "s/^\$/-p <graft-id>/"' HEAD
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-------------------------------------------------------------------
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(if the parent string is empty - which happens when we are dealing with
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the initial commit - add graftcommit as a parent). Note that this assumes
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history with a single root (that is, no merge without common ancestors
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happened). If this is not the case, use:
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--------------------------------------------------------------------------
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git filter-branch --parent-filter \
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'test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>" || cat' HEAD
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--------------------------------------------------------------------------
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or even simpler:
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-----------------------------------------------
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echo "$commit-id $graft-id" >> .git/info/grafts
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git filter-branch $graft-id..HEAD
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-----------------------------------------------
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To remove commits authored by "Darl McBribe" from the history:
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------------------------------------------------------------------------------
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git filter-branch --commit-filter '
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if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ];
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then
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skip_commit "$@";
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else
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git commit-tree "$@";
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fi' HEAD
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------------------------------------------------------------------------------
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The function 'skip_commit' is defined as follows:
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--------------------------
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skip_commit()
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{
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shift;
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while [ -n "$1" ];
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do
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shift;
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map "$1";
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shift;
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done;
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}
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--------------------------
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The shift magic first throws away the tree id and then the -p
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parameters. Note that this handles merges properly! In case Darl
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committed a merge between P1 and P2, it will be propagated properly
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and all children of the merge will become merge commits with P1,P2
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as their parents instead of the merge commit.
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You can rewrite the commit log messages using `--msg-filter`. For
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example, 'git-svn-id' strings in a repository created by 'git-svn' can
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be removed this way:
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-------------------------------------------------------
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git filter-branch --msg-filter '
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sed -e "/^git-svn-id:/d"
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'
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-------------------------------------------------------
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To restrict rewriting to only part of the history, specify a revision
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range in addition to the new branch name. The new branch name will
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point to the top-most revision that a 'git-rev-list' of this range
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will print.
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*NOTE* the changes introduced by the commits, and which are not reverted
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by subsequent commits, will still be in the rewritten branch. If you want
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to throw out _changes_ together with the commits, you should use the
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interactive mode of 'git-rebase'.
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Consider this history:
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------------------
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D--E--F--G--H
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/ /
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A--B-----C
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------------------
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To rewrite only commits D,E,F,G,H, but leave A, B and C alone, use:
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--------------------------------
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git filter-branch ... C..H
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--------------------------------
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To rewrite commits E,F,G,H, use one of these:
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----------------------------------------
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git filter-branch ... C..H --not D
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git filter-branch ... D..H --not C
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----------------------------------------
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To move the whole tree into a subdirectory, or remove it from there:
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---------------------------------------------------------------
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git filter-branch --index-filter \
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'git ls-files -s | sed "s-\t-&newsubdir/-" |
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GIT_INDEX_FILE=$GIT_INDEX_FILE.new \
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git update-index --index-info &&
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mv $GIT_INDEX_FILE.new $GIT_INDEX_FILE' HEAD
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---------------------------------------------------------------
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Checklist for Shrinking a Repository
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------------------------------------
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git-filter-branch is often used to get rid of a subset of files,
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usually with some combination of `\--index-filter` and
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`\--subdirectory-filter`. People expect the resulting repository to
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be smaller than the original, but you need a few more steps to
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actually make it smaller, because git tries hard not to lose your
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objects until you tell it to. First make sure that:
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* You really removed all variants of a filename, if a blob was moved
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over its lifetime. `git log \--name-only \--follow \--all \--
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filename` can help you find renames.
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* You really filtered all refs: use `\--tag-name-filter cat \--
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\--all` when calling git-filter-branch.
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Then there are two ways to get a smaller repository. A safer way is
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to clone, that keeps your original intact.
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* Clone it with `git clone +++file:///path/to/repo+++`. The clone
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will not have the removed objects. See linkgit:git-clone[1]. (Note
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that cloning with a plain path just hardlinks everything!)
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If you really don't want to clone it, for whatever reasons, check the
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following points instead (in this order). This is a very destructive
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approach, so *make a backup* or go back to cloning it. You have been
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warned.
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* Remove the original refs backed up by git-filter-branch: say `git
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for-each-ref \--format="%(refname)" refs/original/ | xargs -n 1 git
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update-ref -d`.
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* Expire all reflogs with `git reflog expire \--expire=now \--all`.
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* Garbage collect all unreferenced objects with `git gc \--prune=now`
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(or if your git-gc is not new enough to support arguments to
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`\--prune`, use `git repack -ad; git prune` instead).
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Author
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------
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Written by Petr "Pasky" Baudis <pasky@suse.cz>,
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and the git list <git@vger.kernel.org>
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Documentation
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--------------
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Documentation by Petr Baudis and the git list.
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GIT
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---
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Part of the linkgit:git[1] suite
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