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Diffstat (limited to 'Documentation/git-filter-branch.txt')
| -rw-r--r-- | Documentation/git-filter-branch.txt | 172 |
1 files changed, 114 insertions, 58 deletions
diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt index 2b40bab..73fd9e8 100644 --- a/Documentation/git-filter-branch.txt +++ b/Documentation/git-filter-branch.txt @@ -18,7 +18,7 @@ SYNOPSIS DESCRIPTION ----------- -Lets you rewrite git revision history by rewriting the branches mentioned +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. @@ -29,11 +29,13 @@ The command will only rewrite the _positive_ refs mentioned in the 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, +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. +*NOTE*: This command honors `.git/info/grafts` file and refs in +the `refs/replace/` namespace. +If you have any grafts or replacement refs 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 @@ -62,8 +64,11 @@ argument is always evaluated in the shell context using the 'eval' command 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. The values -of these variables after the filters have run, are used for the new commit. +and GIT_COMMITTER_DATE are taken from the current commit and exported to +the environment, in order to affect the author and committer identities of +the replacement commit created by linkgit:git-commit-tree[1] after the +filters have run. + If any evaluation of <command> returns a non-zero exit status, the whole operation will be aborted. @@ -81,7 +86,7 @@ OPTIONS 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 + variables (see linkgit:git-commit-tree[1] for details). Do not forget to re-export the variables. --tree-filter <command>:: @@ -95,8 +100,8 @@ OPTIONS --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. Frequently used with `git rm \--cached - \--ignore-unmatch ...`, see EXAMPLES below. For hairy + faster. Frequently used with `git rm --cached + --ignore-unmatch ...`, see EXAMPLES below. For hairy cases, see linkgit:git-update-index[1]. --parent-filter <command>:: @@ -116,8 +121,8 @@ OPTIONS --commit-filter <command>:: This is the filter for performing the commit. If this filter is specified, it will be called instead of the - 'git-commit-tree' command, with arguments of the form - "<TREE_ID> [-p <PARENT_COMMIT_ID>]..." and the log message on + '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 @@ -127,10 +132,10 @@ 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 'git-rebase' 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 +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>:: @@ -159,7 +164,7 @@ 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. + project root. Implies <<Remap_to_ancestor>>. --prune-empty:: Some kind of filters will generate empty commits, that left the tree @@ -168,7 +173,7 @@ to other tags will be rewritten to point to the underlying commit. 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 + of the `git commit-tree "$@"` idiom in your commit filter to make that happen. --original <namespace>:: @@ -185,15 +190,26 @@ to other tags will be rewritten to point to the underlying commit. -f:: --force:: - 'git-filter-branch' refuses to start with an existing temporary + '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>...:: - Arguments for 'git-rev-list'. All positive refs included by + 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. + the 'git filter-branch' options. Implies <<Remap_to_ancestor>>. + + +[[Remap_to_ancestor]] +Remap to ancestor +~~~~~~~~~~~~~~~~~ + +By using linkgit:rev-list[1] arguments, e.g., path limiters, you can limit the +set of revisions which get rewritten. However, positive refs on the command +line are distinguished: we don't let them be excluded by such limiters. For +this purpose, they are instead rewritten to point at the nearest ancestor that +was not excluded. Examples @@ -210,11 +226,11 @@ 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 +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`: +history, so we also add `--ignore-unmatch`: -------------------------------------------------------------------------- git filter-branch --index-filter 'git rm --cached --ignore-unmatch filename' HEAD @@ -230,8 +246,8 @@ 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. +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 @@ -291,8 +307,13 @@ 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. +*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 'git rebase'. + You can rewrite the commit log messages using `--msg-filter`. For -example, 'git-svn-id' strings in a repository created by 'git-svn' can +example, 'git svn-id' strings in a repository created by 'git svn' can be removed this way: ------------------------------------------------------- @@ -301,11 +322,6 @@ git filter-branch --msg-filter ' ' ------------------------------------------------------- -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. - If you need to add 'Acked-by' lines to, say, the last 10 commits (none of which is a merge), use this command: @@ -316,11 +332,30 @@ git filter-branch --msg-filter ' ' HEAD~10..HEAD -------------------------------------------------------- -*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 'git-rebase'. +The `--env-filter` option can be used to modify committer and/or author +identity. For example, if you found out that your commits have the wrong +identity due to a misconfigured user.email, you can make a correction, +before publishing the project, like this: +-------------------------------------------------------- +git filter-branch --env-filter ' + if test "$GIT_AUTHOR_EMAIL" = "root@localhost" + then + GIT_AUTHOR_EMAIL=john@example.com + export GIT_AUTHOR_EMAIL + fi + if test "$GIT_COMMITTER_EMAIL" = "root@localhost" + then + GIT_COMMITTER_EMAIL=john@example.com + export GIT_COMMITTER_EMAIL + fi +' -- --all +-------------------------------------------------------- + +To restrict rewriting to only part of the history, specify a revision +range in addition to the new branch name. The new branch name will +point to the top-most revision that a 'git rev-list' of this range +will print. Consider this history: @@ -347,10 +382,10 @@ To move the whole tree into a subdirectory, or remove it from there: --------------------------------------------------------------- git filter-branch --index-filter \ - 'git ls-files -s | sed "s-\t-&newsubdir/-" | + 'git ls-files -s | sed "s-\t\"*-&newsubdir/-" | GIT_INDEX_FILE=$GIT_INDEX_FILE.new \ git update-index --index-info && - mv $GIT_INDEX_FILE.new $GIT_INDEX_FILE' HEAD + mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' HEAD --------------------------------------------------------------- @@ -358,24 +393,24 @@ git filter-branch --index-filter \ 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 +git-filter-branch can be 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 +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. + 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. +* 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 +* 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!) @@ -385,24 +420,45 @@ 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 + for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d`. -* Expire all reflogs with `git reflog expire \--expire=now \--all`. +* Expire all reflogs with `git reflog expire --expire=now --all`. -* Garbage collect all unreferenced objects with `git gc \--prune=now` +* 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>, -and the git list <git@vger.kernel.org> - -Documentation --------------- -Documentation by Petr Baudis and the git list. + `--prune`, use `git repack -ad; git prune` instead). + +Notes +----- + +git-filter-branch allows you to make complex shell-scripted rewrites +of your Git history, but you probably don't need this flexibility if +you're simply _removing unwanted data_ like large files or passwords. +For those operations you may want to consider +http://rtyley.github.io/bfg-repo-cleaner/[The BFG Repo-Cleaner], +a JVM-based alternative to git-filter-branch, typically at least +10-50x faster for those use-cases, and with quite different +characteristics: + +* Any particular version of a file is cleaned exactly _once_. The BFG, + unlike git-filter-branch, does not give you the opportunity to + handle a file differently based on where or when it was committed + within your history. This constraint gives the core performance + benefit of The BFG, and is well-suited to the task of cleansing bad + data - you don't care _where_ the bad data is, you just want it + _gone_. + +* By default The BFG takes full advantage of multi-core machines, + cleansing commit file-trees in parallel. git-filter-branch cleans + commits sequentially (i.e. in a single-threaded manner), though it + _is_ possible to write filters that include their own parallelism, + in the scripts executed against each commit. + +* The http://rtyley.github.io/bfg-repo-cleaner/#examples[command options] + are much more restrictive than git-filter branch, and dedicated just + to the tasks of removing unwanted data- e.g: + `--strip-blobs-bigger-than 1M`. GIT --- |