Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
GIT-FILTER-BRANCH(1)		  Git Manual		  GIT-FILTER-BRANCH(1)

NAME
       git-filter-branch - Rewrite branches

SYNOPSIS
       git filter-branch [--setup <command>] [--subdirectory-filter <directory>]
	       [--env-filter <command>]	[--tree-filter <command>]
	       [--index-filter <command>] [--parent-filter <command>]
	       [--msg-filter <command>]	[--commit-filter <command>]
	       [--tag-name-filter <command>] [--prune-empty]
	       [--original <namespace>]	[-d <directory>] [-f | --force]
	       [--state-branch <branch>] [--] [<rev-list options>...]

WARNING
       git filter-branch has a plethora	of pitfalls that can produce
       non-obvious manglings of	the intended history rewrite (and can leave
       you with	little time to investigate such	problems since it has such
       abysmal performance). These safety and performance issues cannot	be
       backward	compatibly fixed and as	such, its use is not recommended.
       Please use an alternative history filtering tool	such as	git
       filter-repo[1]. If you still need to use	git filter-branch, please
       carefully read the section called "SAFETY" (and the section called
       "PERFORMANCE") to learn about the land mines of filter-branch, and then
       vigilantly avoid	as many	of the hazards listed there as reasonably
       possible.

DESCRIPTION
       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 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,
       therefore such a	usage is permitted.

       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 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.	(See the "RECOVERING
       FROM UPSTREAM REBASE" section in	git-rebase(1) for further information
       about rewriting published history.)

       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 very I/O expensive, it	might 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
       The filters are applied in the order as listed below. The <command>
       argument	is always evaluated in the shell context 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 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 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.

       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
       --setup <command>
	   This	is not a real filter executed for each commit but a one	time
	   setup just before the loop. Therefore no commit-specific variables
	   are defined yet. Functions or variables defined here	can be used or
	   modified in the following filter steps except the commit filter,
	   for technical reasons.

       --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. Implies the section called "Remap to ancestor".

       --env-filter <command>
	   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 git-commit-tree(1) for details).

       --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. Frequently used with	git rm --cached	--ignore-unmatch ...,
	   see EXAMPLES	below. For hairy cases,	see 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 the format	described in
	   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 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 commit
	   ids;	in that	case, the rewritten children 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 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 and that makes no change to the tree.

       --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.

	   Nearly proper rewriting of tag objects is supported.	If the tag has
	   a message attached, a new tag object	will be	created	with the same
	   message, author, and	timestamp. If the tag has a signature
	   attached, the signature will	be stripped. It	is by definition
	   impossible to preserve signatures. The reason this is "nearly"
	   proper, is because ideally if the tag did not change	(points	to the
	   same	object,	has the	same name, etc.) it should retain any
	   signature. That is not the case, signatures will always be removed,
	   buyer beware. There is also no support for changing the author or
	   timestamp (or the tag message for that matter). Tags	which point to
	   other tags will be rewritten	to point to the	underlying commit.

       --prune-empty
	   Some	filters	will generate empty commits that leave the tree
	   untouched. This option instructs git-filter-branch to remove	such
	   commits if they have	exactly	one or zero non-pruned parents;	merge
	   commits will	therefore remain intact. This option cannot be used
	   together with --commit-filter, though the same effect can be
	   achieved by using the provided git_commit_non_empty_tree function
	   in a	commit filter.

       --original <namespace>
	   Use this option to set the namespace	where the original commits
	   will	be stored. The default value is	refs/original.

       -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
	   temporarily check out 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.

       --state-branch <branch>
	   This	option will cause the mapping from old to new objects to be
	   loaded from named branch upon startup and saved as a	new commit to
	   that	branch upon exit, enabling incremental of large	trees. If
	   _branch_ does not exist it will be created.

       <rev-list options>...
	   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. Implies the	section	called "Remap to ancestor".

   Remap to ancestor
       By using	git-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.

EXIT STATUS
       On success, the exit status is 0. If the	filter can't find any commits
       to rewrite, the exit status is 2. On any	other error, the exit status
       may be any other	non-zero value.

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

       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 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:

	   git filter-branch --index-filter 'git rm --cached --ignore-unmatch filename'	HEAD

       Now, you	will get the rewritten history saved in	HEAD.

       To rewrite the repository to look as if foodir/ had been	its project
       root, and discard all other history:

	   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.

       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 -	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 \
		   'test $GIT_COMMIT = <commit-id> && echo "-p <graft-id>" || cat' HEAD

       or even simpler:

	   git replace --graft $commit-id $graft-id
	   git filter-branch $graft-id..HEAD

       To remove commits authored by "Darl McBribe" from the history:

	   git filter-branch --commit-filter '
		   if [	"$GIT_AUTHOR_NAME" = "Darl McBribe" ];
		   then
			   skip_commit "$@";
		   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.

       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 be
       removed this way:

	   git filter-branch --msg-filter '
		   sed -e "/^git-svn-id:/d"
	   '

       If you need to add Acked-by lines to, say, the last 10 commits (none of
       which is	a merge), use this command:

	   git filter-branch --msg-filter '
		   cat &&
		   echo	"Acked-by: Bugs	Bunny <bunny@bugzilla.org>"
	   ' HEAD~10..HEAD

       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 "$GIT_AUTHOR_EMAIL" = "root@localhost"
		   then
			   GIT_AUTHOR_EMAIL=john@example.com
		   fi
		   if test "$GIT_COMMITTER_EMAIL" = "root@localhost"
		   then
			   GIT_COMMITTER_EMAIL=john@example.com
		   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:

		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

CHECKLIST FOR SHRINKING	A REPOSITORY
       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 objects until you tell it to. First make
       sure that:

       o   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.

       o   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.

       o   Clone it with git clone file:///path/to/repo. The clone will	not
	   have	the removed objects. See git-clone(1). (Note that cloning with
	   a plain path	just hardlinks everything!)

       If you really don't want	to clone it, for whatever reasons, check the
       following points	instead	(in this order). This is a very	destructive
       approach, so make a backup or go	back to	cloning	it. You	have been
       warned.

       o   Remove the original refs backed up by git-filter-branch: say	git
	   for-each-ref	--format="%(refname)" refs/original/ | xargs -n	1 git
	   update-ref -d.

       o   Expire all reflogs with git reflog expire --expire=now --all.

       o   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).

PERFORMANCE
       The performance of git-filter-branch is glacially slow; its design
       makes it	impossible for a backward-compatible implementation to ever be
       fast:

       o   In editing files, git-filter-branch by design checks	out each and
	   every commit	as it existed in the original repo. If your repo has
	   10^5	files and 10^5 commits,	but each commit	only modifies five
	   files, then git-filter-branch will make you do 10^10	modifications,
	   despite only	having (at most) 5*10^5	unique blobs.

       o   If you try and cheat	and try	to make	git-filter-branch only work on
	   files modified in a commit, then two	things happen

	   o   you run into problems with deletions whenever the user is
	       simply trying to	rename files (because attempting to delete
	       files that don't	exist looks like a no-op; it takes some
	       chicanery to remap deletes across file renames when the renames
	       happen via arbitrary user-provided shell)

	   o   even if you succeed at the map-deletes-for-renames chicanery,
	       you still technically violate backward compatibility because
	       users are allowed to filter files in ways that depend upon
	       topology	of commits instead of filtering	solely based on	file
	       contents	or names (though this has not been observed in the
	       wild).

       o   Even	if you don't need to edit files	but only want to e.g. rename
	   or remove some and thus can avoid checking out each file (i.e. you
	   can use --index-filter), you	still are passing shell	snippets for
	   your	filters. This means that for every commit, you have to have a
	   prepared git	repo where those filters can be	run. That's a
	   significant setup.

       o   Further, several additional files are created or updated per	commit
	   by git-filter-branch. Some of these are for supporting the
	   convenience functions provided by git-filter-branch (such as
	   map()), while others	are for	keeping	track of internal state	(but
	   could have also been	accessed by user filters; one of
	   git-filter-branch's regression tests	does so). This essentially
	   amounts to using the	filesystem as an IPC mechanism between
	   git-filter-branch and the user-provided filters. Disks tend to be a
	   slow	IPC mechanism, and writing these files also effectively
	   represents a	forced synchronization point between separate
	   processes that we hit with every commit.

       o   The user-provided shell commands will likely	involve	a pipeline of
	   commands, resulting in the creation of many processes per commit.
	   Creating and	running	another	process	takes a	widely varying amount
	   of time between operating systems, but on any platform it is	very
	   slow	relative to invoking a function.

       o   git-filter-branch itself is written in shell, which is kind of
	   slow. This is the one performance issue that	could be
	   backward-compatibly fixed, but compared to the above	problems that
	   are intrinsic to the	design of git-filter-branch, the language of
	   the tool itself is a	relatively minor issue.

	   o   Side note: Unfortunately, people	tend to	fixate on the
	       written-in-shell	aspect and periodically	ask if
	       git-filter-branch could be rewritten in another language	to fix
	       the performance issues. Not only	does that ignore the bigger
	       intrinsic problems with the design, it'd	help less than you'd
	       expect: if git-filter-branch itself were	not shell, then	the
	       convenience functions (map(), skip_commit(), etc) and the
	       --setup argument	could no longer	be executed once at the
	       beginning of the	program	but would instead need to be prepended
	       to every	user filter (and thus re-executed with every commit).

       The git filter-repo[1] tool is an alternative to	git-filter-branch
       which does not suffer from these	performance problems or	the safety
       problems	(mentioned below). For those with existing tooling which
       relies upon git-filter-branch, git repo-filter also provides
       filter-lamely[2], a drop-in git-filter-branch replacement (with a few
       caveats). While filter-lamely suffers from all the same safety issues
       as git-filter-branch, it	at least ameliorates the performance issues a
       little.

SAFETY
       git-filter-branch is riddled with gotchas resulting in various ways to
       easily corrupt repos or end up with a mess worse	than what you started
       with:

       o   Someone can have a set of "working and tested filters" which	they
	   document or provide to a coworker, who then runs them on a
	   different OS	where the same commands	are not	working/tested (some
	   examples in the git-filter-branch manpage are also affected by
	   this). BSD vs. GNU userland differences can really bite. If lucky,
	   error messages are spewed. But just as likely, the commands either
	   don't do the	filtering requested, or	silently corrupt by making
	   some	unwanted change. The unwanted change may only affect a few
	   commits, so it's not	necessarily obvious either. (The fact that
	   problems won't necessarily be obvious means they are	likely to go
	   unnoticed until the rewritten history is in use for quite a while,
	   at which point it's really hard to justify another flag-day for
	   another rewrite.)

       o   Filenames with spaces are often mishandled by shell snippets	since
	   they	cause problems for shell pipelines. Not	everyone is familiar
	   with	find -print0, xargs -0,	git-ls-files -z, etc. Even people who
	   are familiar	with these may assume such flags are not relevant
	   because someone else	renamed	any such files in their	repo back
	   before the person doing the filtering joined	the project. And
	   often, even those familiar with handling arguments with spaces may
	   not do so just because they aren't in the mindset of	thinking about
	   everything that could possibly go wrong.

       o   Non-ascii filenames can be silently removed despite being in	a
	   desired directory. Keeping only wanted paths	is often done using
	   pipelines like git ls-files | grep -v ^WANTED_DIR/ |	xargs git rm.
	   ls-files will only quote filenames if needed, so folks may not
	   notice that one of the files	didn't match the regex (at least not
	   until it's much too late). Yes, someone who knows about
	   core.quotePath can avoid this (unless they have other special
	   characters like \t, \n, or "), and people who use ls-files -z with
	   something other than	grep can avoid this, but that doesn't mean
	   they	will.

       o   Similarly, when moving files	around,	one can	find that filenames
	   with	non-ascii or special characters	end up in a different
	   directory, one that includes	a double quote character. (This	is
	   technically the same	issue as above with quoting, but perhaps an
	   interesting different way that it can and has manifested as a
	   problem.)

       o   It's	far too	easy to	accidentally mix up old	and new	history. It's
	   still possible with any tool, but git-filter-branch almost invites
	   it. If lucky, the only downside is users getting frustrated that
	   they	don't know how to shrink their repo and	remove the old stuff.
	   If unlucky, they merge old and new history and end up with multiple
	   "copies" of each commit, some of which have unwanted	or sensitive
	   files and others which don't. This comes about in multiple
	   different ways:

	   o   the default to only doing a partial history rewrite (--all is
	       not the default and few examples	show it)

	   o   the fact	that there's no	automatic post-run cleanup

	   o   the fact	that --tag-name-filter (when used to rename tags)
	       doesn't remove the old tags but just adds new ones with the new
	       name

	   o   the fact	that little educational	information is provided	to
	       inform users of the ramifications of a rewrite and how to avoid
	       mixing old and new history. For example,	this man page
	       discusses how users need	to understand that they	need to	rebase
	       their changes for all their branches on top of new history (or
	       delete and reclone), but	that's only one	of multiple concerns
	       to consider. See	the "DISCUSSION" section of the	git
	       filter-repo manual page for more	details.

       o   Annotated tags can be accidentally converted	to lightweight tags,
	   due to either of two	issues:

	   o   Someone can do a	history	rewrite, realize they messed up,
	       restore from the	backups	in refs/original/, and then redo their
	       git-filter-branch command. (The backup in refs/original/	is not
	       a real backup; it dereferences tags first.)

	   o   Running git-filter-branch with either --tags or --all in	your
	       <rev-list options>. In order to retain annotated	tags as
	       annotated, you must use --tag-name-filter (and must not have
	       restored	from refs/original/ in a previously botched rewrite).

       o   Any commit messages that specify an encoding	will become corrupted
	   by the rewrite; git-filter-branch ignores the encoding, takes the
	   original bytes, and feeds it	to commit-tree without telling it the
	   proper encoding. (This happens whether or not --msg-filter is
	   used.)

       o   Commit messages (even if they are all UTF-8)	by default become
	   corrupted due to not	being updated -- any references	to other
	   commit hashes in commit messages will now refer to no-longer-extant
	   commits.

       o   There are no	facilities for helping users find what unwanted	crud
	   they	should delete, which means they	are much more likely to	have
	   incomplete or partial cleanups that sometimes result	in confusion
	   and people wasting time trying to understand. (For example, folks
	   tend	to just	look for big files to delete instead of	big
	   directories or extensions, and once they do so, then	sometime later
	   folks using the new repository who are going	through	history	will
	   notice a build artifact directory that has some files but not
	   others, or a	cache of dependencies (node_modules or similar)	which
	   couldn't have ever been functional since it's missing some files.)

       o   If --prune-empty isn't specified, then the filtering	process	can
	   create hoards of confusing empty commits

       o   If --prune-empty is specified, then intentionally placed empty
	   commits from	before the filtering operation are also	pruned instead
	   of just pruning commits that	became empty due to filtering rules.

       o   If --prune-empty is specified, sometimes empty commits are missed
	   and left around anyway (a somewhat rare bug,	but it happens...)

       o   A minor issue, but users who	have a goal to update all names	and
	   emails in a repository may be led to	--env-filter which will	only
	   update authors and committers, missing taggers.

       o   If the user provides	a --tag-name-filter that maps multiple tags to
	   the same name, no warning or	error is provided; git-filter-branch
	   simply overwrites each tag in some undocumented pre-defined order
	   resulting in	only one tag at	the end. (A git-filter-branch
	   regression test requires this surprising behavior.)

       Also, the poor performance of git-filter-branch often leads to safety
       issues:

       o   Coming up with the correct shell snippet to do the filtering	you
	   want	is sometimes difficult unless you're just doing	a trivial
	   modification	such as	deleting a couple files. Unfortunately,	people
	   often learn if the snippet is right or wrong	by trying it out, but
	   the rightness or wrongness can vary depending on special
	   circumstances (spaces in filenames, non-ascii filenames, funny
	   author names	or emails, invalid timezones, presence of grafts or
	   replace objects, etc.), meaning they	may have to wait a long	time,
	   hit an error, then restart. The performance of git-filter-branch is
	   so bad that this cycle is painful, reducing the time	available to
	   carefully re-check (to say nothing about what it does to the
	   patience of the person doing	the rewrite even if they do
	   technically have more time available). This problem is extra
	   compounded because errors from broken filters may not be shown for
	   a long time and/or get lost in a sea	of output. Even	worse, broken
	   filters often just result in	silent incorrect rewrites.

       o   To top it all off, even when	users finally find working commands,
	   they	naturally want to share	them. But they may be unaware that
	   their repo didn't have some special cases that someone else's does.
	   So, when someone else with a	different repository runs the same
	   commands, they get hit by the problems above. Or, the user just
	   runs	commands that really were vetted for special cases, but	they
	   run it on a different OS where it doesn't work, as noted above.

GIT
       Part of the git(1) suite

NOTES
	1. git filter-repo
	   https://github.com/newren/git-filter-repo/

	2. filter-lamely
	   https://github.com/newren/git-filter-repo/blob/master/contrib/filter-repo-demos/filter-lamely

Git 2.28.0			  07/26/2020		  GIT-FILTER-BRANCH(1)

NAME | SYNOPSIS | WARNING | DESCRIPTION | OPTIONS | EXIT STATUS | EXAMPLES | CHECKLIST FOR SHRINKING A REPOSITORY | PERFORMANCE | SAFETY | GIT | NOTES

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=git-filter-branch&sektion=1&manpath=FreeBSD+12.1-RELEASE+and+Ports>

home | help