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GIT-REBASE(1)			  Git Manual			 GIT-REBASE(1)

NAME
       git-rebase - Reapply commits on top of another base tip

SYNOPSIS
       git rebase [-i |	--interactive] [options] [--exec <cmd>]	[--onto	<newbase>]
	       [<upstream> [<branch>]]
       git rebase [-i |	--interactive] [options] [--exec <cmd>]	[--onto	<newbase>]
	       --root [<branch>]
       git rebase --continue | --skip |	--abort	| --quit | --edit-todo

DESCRIPTION
       If <branch> is specified, git rebase will perform an automatic git
       checkout	<branch> before	doing anything else. Otherwise it remains on
       the current branch.

       If <upstream> is	not specified, the upstream configured in
       branch.<name>.remote and	branch.<name>.merge options will be used (see
       git-config(1) for details) and the --fork-point option is assumed. If
       you are currently not on	any branch or if the current branch does not
       have a configured upstream, the rebase will abort.

       All changes made	by commits in the current branch but that are not in
       <upstream> are saved to a temporary area. This is the same set of
       commits that would be shown by git log <upstream>..HEAD;	or by git log
       'fork_point'..HEAD, if --fork-point is active (see the description on
       --fork-point below); or by git log HEAD,	if the --root option is
       specified.

       The current branch is reset to <upstream>, or <newbase> if the --onto
       option was supplied. This has the exact same effect as git reset	--hard
       <upstream> (or <newbase>). ORIG_HEAD is set to point at the tip of the
       branch before the reset.

       The commits that	were previously	saved into the temporary area are then
       reapplied to the	current	branch,	one by one, in order. Note that	any
       commits in HEAD which introduce the same	textual	changes	as a commit in
       HEAD..<upstream>	are omitted (i.e., a patch already accepted upstream
       with a different	commit message or timestamp will be skipped).

       It is possible that a merge failure will	prevent	this process from
       being completely	automatic. You will have to resolve any	such merge
       failure and run git rebase --continue. Another option is	to bypass the
       commit that caused the merge failure with git rebase --skip. To check
       out the original	<branch> and remove the	.git/rebase-apply working
       files, use the command git rebase --abort instead.

       Assume the following history exists and the current branch is "topic":

		     A---B---C topic
		    /
	       D---E---F---G master

       From this point,	the result of either of	the following commands:

	   git rebase master
	   git rebase master topic

       would be:

			     A'--B'--C'	topic
			    /
	       D---E---F---G master

       NOTE: The latter	form is	just a short-hand of git checkout topic
       followed	by git rebase master. When rebase exits	topic will remain the
       checked-out branch.

       If the upstream branch already contains a change	you have made (e.g.,
       because you mailed a patch which	was applied upstream), then that
       commit will be skipped. For example, running git	rebase master on the
       following history (in which A' and A introduce the same set of changes,
       but have	different committer information):

		     A---B---C topic
		    /
	       D---E---A'---F master

       will result in:

			      B'---C' topic
			     /
	       D---E---A'---F master

       Here is how you would transplant	a topic	branch based on	one branch to
       another,	to pretend that	you forked the topic branch from the latter
       branch, using rebase --onto.

       First let's assume your topic is	based on branch	next. For example, a
       feature developed in topic depends on some functionality	which is found
       in next.

	       o---o---o---o---o  master
		    \
		     o---o---o---o---o	next
				      \
				       o---o---o  topic

       We want to make topic forked from branch	master;	for example, because
       the functionality on which topic	depends	was merged into	the more
       stable master branch. We	want our tree to look like this:

	       o---o---o---o---o  master
		   |		\
		   |		 o'--o'--o'  topic
		    \
		     o---o---o---o---o	next

       We can get this using the following command:

	   git rebase --onto master next topic

       Another example of --onto option	is to rebase part of a branch. If we
       have the	following situation:

				       H---I---J topicB
				      /
			     E---F---G	topicA
			    /
	       A---B---C---D  master

       then the	command

	   git rebase --onto master topicA topicB

       would result in:

			    H'--I'--J'	topicB
			   /
			   | E---F---G	topicA
			   |/
	       A---B---C---D  master

       This is useful when topicB does not depend on topicA.

       A range of commits could	also be	removed	with rebase. If	we have	the
       following situation:

	       E---F---G---H---I---J  topicA

       then the	command

	   git rebase --onto topicA~5 topicA~3 topicA

       would result in the removal of commits F	and G:

	       E---H'---I'---J'	 topicA

       This is useful if F and G were flawed in	some way, or should not	be
       part of topicA. Note that the argument to --onto	and the	<upstream>
       parameter can be	any valid commit-ish.

       In case of conflict, git	rebase will stop at the	first problematic
       commit and leave	conflict markers in the	tree. You can use git diff to
       locate the markers (<<<<<<) and make edits to resolve the conflict. For
       each file you edit, you need to tell Git	that the conflict has been
       resolved, typically this	would be done with

	   git add <filename>

       After resolving the conflict manually and updating the index with the
       desired resolution, you can continue the	rebasing process with

	   git rebase --continue

       Alternatively, you can undo the git rebase with

	   git rebase --abort

CONFIGURATION
       rebase.stat
	   Whether to show a diffstat of what changed upstream since the last
	   rebase. False by default.

       rebase.autoSquash
	   If set to true enable --autosquash option by	default.

       rebase.autoStash
	   If set to true enable --autostash option by default.

       rebase.missingCommitsCheck
	   If set to "warn", print warnings about removed commits in
	   interactive mode. If	set to "error",	print the warnings and stop
	   the rebase. If set to "ignore", no checking is done.	"ignore" by
	   default.

       rebase.instructionFormat
	   Custom commit list format to	use during an --interactive rebase.

OPTIONS
       --onto <newbase>
	   Starting point at which to create the new commits. If the --onto
	   option is not specified, the	starting point is <upstream>. May be
	   any valid commit, and not just an existing branch name.

	   As a	special	case, you may use "A...B" as a shortcut	for the	merge
	   base	of A and B if there is exactly one merge base. You can leave
	   out at most one of A	and B, in which	case it	defaults to HEAD.

       <upstream>
	   Upstream branch to compare against. May be any valid	commit,	not
	   just	an existing branch name. Defaults to the configured upstream
	   for the current branch.

       <branch>
	   Working branch; defaults to HEAD.

       --continue
	   Restart the rebasing	process	after having resolved a	merge
	   conflict.

       --abort
	   Abort the rebase operation and reset	HEAD to	the original branch.
	   If <branch> was provided when the rebase operation was started,
	   then	HEAD will be reset to <branch>.	Otherwise HEAD will be reset
	   to where it was when	the rebase operation was started.

       --quit
	   Abort the rebase operation but HEAD is not reset back to the
	   original branch. The	index and working tree are also	left unchanged
	   as a	result.

       --keep-empty
	   Keep	the commits that do not	change anything	from its parents in
	   the result.

       --skip
	   Restart the rebasing	process	by skipping the	current	patch.

       --edit-todo
	   Edit	the todo list during an	interactive rebase.

       -m, --merge
	   Use merging strategies to rebase. When the recursive	(default)
	   merge strategy is used, this	allows rebase to be aware of renames
	   on the upstream side.

	   Note	that a rebase merge works by replaying each commit from	the
	   working branch on top of the	<upstream> branch. Because of this,
	   when	a merge	conflict happens, the side reported as ours is the
	   so-far rebased series, starting with	<upstream>, and	theirs is the
	   working branch. In other words, the sides are swapped.

       -s <strategy>, --strategy=<strategy>
	   Use the given merge strategy. If there is no	-s option git
	   merge-recursive is used instead. This implies --merge.

	   Because git rebase replays each commit from the working branch on
	   top of the <upstream> branch	using the given	strategy, using	the
	   ours	strategy simply	discards all patches from the <branch>,	which
	   makes little	sense.

       -X <strategy-option>, --strategy-option=<strategy-option>
	   Pass	the <strategy-option> through to the merge strategy. This
	   implies --merge and,	if no strategy has been	specified, -s
	   recursive. Note the reversal	of ours	and theirs as noted above for
	   the -m option.

       -S[<keyid>], --gpg-sign[=<keyid>]
	   GPG-sign commits. The keyid argument	is optional and	defaults to
	   the committer identity; if specified, it must be stuck to the
	   option without a space.

       -q, --quiet
	   Be quiet. Implies --no-stat.

       -v, --verbose
	   Be verbose. Implies --stat.

       --stat
	   Show	a diffstat of what changed upstream since the last rebase. The
	   diffstat is also controlled by the configuration option
	   rebase.stat.

       -n, --no-stat
	   Do not show a diffstat as part of the rebase	process.

       --no-verify
	   This	option bypasses	the pre-rebase hook. See also githooks(5).

       --verify
	   Allows the pre-rebase hook to run, which is the default. This
	   option can be used to override --no-verify. See also	githooks(5).

       -C<n>
	   Ensure at least <n> lines of	surrounding context match before and
	   after each change. When fewer lines of surrounding context exist
	   they	all must match.	By default no context is ever ignored.

       -f, --force-rebase
	   Force a rebase even if the current branch is	up-to-date and the
	   command without --force would return	without	doing anything.

	   You may find	this (or --no-ff with an interactive rebase) helpful
	   after reverting a topic branch merge, as this option	recreates the
	   topic branch	with fresh commits so it can be	remerged successfully
	   without needing to "revert the reversion" (see the
	   revert-a-faulty-merge How-To[1] for details).

       --fork-point, --no-fork-point
	   Use reflog to find a	better common ancestor between <upstream> and
	   <branch> when calculating which commits have	been introduced	by
	   <branch>.

	   When	--fork-point is	active,	fork_point will	be used	instead	of
	   <upstream> to calculate the set of commits to rebase, where
	   fork_point is the result of git merge-base --fork-point <upstream>
	   <branch> command (see git-merge-base(1)). If	fork_point ends	up
	   being empty,	the <upstream> will be used as a fallback.

	   If either <upstream>	or --root is given on the command line,	then
	   the default is --no-fork-point, otherwise the default is
	   --fork-point.

       --ignore-whitespace, --whitespace=<option>
	   These flag are passed to the	git apply program (see git-apply(1))
	   that	applies	the patch. Incompatible	with the --interactive option.

       --committer-date-is-author-date,	--ignore-date
	   These flags are passed to git am to easily change the dates of the
	   rebased commits (see	git-am(1)). Incompatible with the
	   --interactive option.

       --signoff
	   This	flag is	passed to git am to sign off all the rebased commits
	   (see	git-am(1)). Incompatible with the --interactive	option.

       -i, --interactive
	   Make	a list of the commits which are	about to be rebased. Let the
	   user	edit that list before rebasing.	This mode can also be used to
	   split commits (see SPLITTING	COMMITS	below).

	   The commit list format can be changed by setting the	configuration
	   option rebase.instructionFormat. A customized instruction format
	   will	automatically have the long commit hash	prepended to the
	   format.

       -p, --preserve-merges
	   Recreate merge commits instead of flattening	the history by
	   replaying commits a merge commit introduces.	Merge conflict
	   resolutions or manual amendments to merge commits are not
	   preserved.

	   This	uses the --interactive machinery internally, but combining it
	   with	the --interactive option explicitly is generally not a good
	   idea	unless you know	what you are doing (see	BUGS below).

       -x <cmd>, --exec	<cmd>
	   Append "exec	<cmd>" after each line creating	a commit in the	final
	   history. <cmd> will be interpreted as one or	more shell commands.

	   You may execute several commands by either using one	instance of
	   --exec with several commands:

	       git rebase -i --exec "cmd1 && cmd2 && ..."

	   or by giving	more than one --exec:

	       git rebase -i --exec "cmd1" --exec "cmd2" --exec	...

	   If --autosquash is used, "exec" lines will not be appended for the
	   intermediate	commits, and will only appear at the end of each
	   squash/fixup	series.

	   This	uses the --interactive machinery internally, but it can	be run
	   without an explicit --interactive.

       --root
	   Rebase all commits reachable	from <branch>, instead of limiting
	   them	with an	<upstream>. This allows	you to rebase the root
	   commit(s) on	a branch. When used with --onto, it will skip changes
	   already contained in	<newbase> (instead of <upstream>) whereas
	   without --onto it will operate on every change. When	used together
	   with	both --onto and	--preserve-merges, all root commits will be
	   rewritten to	have <newbase> as parent instead.

       --autosquash, --no-autosquash
	   When	the commit log message begins with "squash! ..." (or "fixup!
	   ..."), and there is a commit	whose title begins with	the same ...,
	   automatically modify	the todo list of rebase	-i so that the commit
	   marked for squashing	comes right after the commit to	be modified,
	   and change the action of the	moved commit from pick to squash (or
	   fixup). Ignores subsequent "fixup! "	or "squash! " after the	first,
	   in case you referred	to an earlier fixup/squash with	git commit
	   --fixup/--squash.

	   This	option is only valid when the --interactive option is used.

	   If the --autosquash option is enabled by default using the
	   configuration variable rebase.autoSquash, this option can be	used
	   to override and disable this	setting.

       --autostash, --no-autostash
	   Automatically create	a temporary stash before the operation begins,
	   and apply it	after the operation ends. This means that you can run
	   rebase on a dirty worktree. However,	use with care: the final stash
	   application after a successful rebase might result in non-trivial
	   conflicts.

       --no-ff
	   With	--interactive, cherry-pick all rebased commits instead of
	   fast-forwarding over	the unchanged ones. This ensures that the
	   entire history of the rebased branch	is composed of new commits.

	   Without --interactive, this is a synonym for	--force-rebase.

	   You may find	this helpful after reverting a topic branch merge, as
	   this	option recreates the topic branch with fresh commits so	it can
	   be remerged successfully without needing to "revert the reversion"
	   (see	the revert-a-faulty-merge How-To[1] for	details).

MERGE STRATEGIES
       The merge mechanism (git	merge and git pull commands) allows the
       backend merge strategies	to be chosen with -s option. Some strategies
       can also	take their own options,	which can be passed by giving
       -X<option> arguments to git merge and/or	git pull.

       resolve
	   This	can only resolve two heads (i.e. the current branch and
	   another branch you pulled from) using a 3-way merge algorithm. It
	   tries to carefully detect criss-cross merge ambiguities and is
	   considered generally	safe and fast.

       recursive
	   This	can only resolve two heads using a 3-way merge algorithm. When
	   there is more than one common ancestor that can be used for 3-way
	   merge, it creates a merged tree of the common ancestors and uses
	   that	as the reference tree for the 3-way merge. This	has been
	   reported to result in fewer merge conflicts without causing
	   mismerges by	tests done on actual merge commits taken from Linux
	   2.6 kernel development history. Additionally	this can detect	and
	   handle merges involving renames. This is the	default	merge strategy
	   when	pulling	or merging one branch.

	   The recursive strategy can take the following options:

	   ours
	       This option forces conflicting hunks to be auto-resolved
	       cleanly by favoring our version.	Changes	from the other tree
	       that do not conflict with our side are reflected	to the merge
	       result. For a binary file, the entire contents are taken	from
	       our side.

	       This should not be confused with	the ours merge strategy, which
	       does not	even look at what the other tree contains at all. It
	       discards	everything the other tree did, declaring our history
	       contains	all that happened in it.

	   theirs
	       This is the opposite of ours.

	   patience
	       With this option, merge-recursive spends	a little extra time to
	       avoid mismerges that sometimes occur due	to unimportant
	       matching	lines (e.g., braces from distinct functions). Use this
	       when the	branches to be merged have diverged wildly. See	also
	       git-diff(1)--patience.

	   diff-algorithm=[patience|minimal|histogram|myers]
	       Tells merge-recursive to	use a different	diff algorithm,	which
	       can help	avoid mismerges	that occur due to unimportant matching
	       lines (such as braces from distinct functions). See also	git-
	       diff(1)--diff-algorithm.

	   ignore-space-change,	ignore-all-space, ignore-space-at-eol
	       Treats lines with the indicated type of whitespace change as
	       unchanged for the sake of a three-way merge. Whitespace changes
	       mixed with other	changes	to a line are not ignored. See also
	       git-diff(1)-b, -w, and --ignore-space-at-eol.

	       o   If their version only introduces whitespace changes to a
		   line, our version is	used;

	       o   If our version introduces whitespace	changes	but their
		   version includes a substantial change, their	version	is
		   used;

	       o   Otherwise, the merge	proceeds in the	usual way.

	   renormalize
	       This runs a virtual check-out and check-in of all three stages
	       of a file when resolving	a three-way merge. This	option is
	       meant to	be used	when merging branches with different clean
	       filters or end-of-line normalization rules. See "Merging
	       branches	with differing checkin/checkout	attributes" in
	       gitattributes(5)	for details.

	   no-renormalize
	       Disables	the renormalize	option.	This overrides the
	       merge.renormalize configuration variable.

	   no-renames
	       Turn off	rename detection. See also git-diff(1)--no-renames.

	   find-renames[=<n>]
	       Turn on rename detection, optionally setting the	similarity
	       threshold. This is the default. See also	git-
	       diff(1)--find-renames.

	   rename-threshold=<n>
	       Deprecated synonym for find-renames=<n>.

	   subtree[=<path>]
	       This option is a	more advanced form of subtree strategy,	where
	       the strategy makes a guess on how two trees must	be shifted to
	       match with each other when merging. Instead, the	specified path
	       is prefixed (or stripped	from the beginning) to make the	shape
	       of two trees to match.

       octopus
	   This	resolves cases with more than two heads, but refuses to	do a
	   complex merge that needs manual resolution. It is primarily meant
	   to be used for bundling topic branch	heads together.	This is	the
	   default merge strategy when pulling or merging more than one
	   branch.

       ours
	   This	resolves any number of heads, but the resulting	tree of	the
	   merge is always that	of the current branch head, effectively
	   ignoring all	changes	from all other branches. It is meant to	be
	   used	to supersede old development history of	side branches. Note
	   that	this is	different from the -Xours option to the	recursive
	   merge strategy.

       subtree
	   This	is a modified recursive	strategy. When merging trees A and B,
	   if B	corresponds to a subtree of A, B is first adjusted to match
	   the tree structure of A, instead of reading the trees at the	same
	   level. This adjustment is also done to the common ancestor tree.

       With the	strategies that	use 3-way merge	(including the default,
       recursive), if a	change is made on both branches, but later reverted on
       one of the branches, that change	will be	present	in the merged result;
       some people find	this behavior confusing. It occurs because only	the
       heads and the merge base	are considered when performing a merge,	not
       the individual commits. The merge algorithm therefore considers the
       reverted	change as no change at all, and	substitutes the	changed
       version instead.

NOTES
       You should understand the implications of using git rebase on a
       repository that you share. See also RECOVERING FROM UPSTREAM REBASE
       below.

       When the	git-rebase command is run, it will first execute a
       "pre-rebase" hook if one	exists.	You can	use this hook to do sanity
       checks and reject the rebase if it isn't	appropriate. Please see	the
       template	pre-rebase hook	script for an example.

       Upon completion,	<branch> will be the current branch.

INTERACTIVE MODE
       Rebasing	interactively means that you have a chance to edit the commits
       which are rebased. You can reorder the commits, and you can remove them
       (weeding	out bad	or otherwise unwanted patches).

       The interactive mode is meant for this type of workflow:

	1. have	a wonderful idea

	2. hack	on the code

	3. prepare a series for	submission

	4. submit

       where point 2. consists of several instances of

       a) regular use

	1. finish something worthy of a	commit

	2. commit

       b) independent fixup

	1. realize that	something does not work

	2. fix that

	3. commit it

       Sometimes the thing fixed in b.2. cannot	be amended to the not-quite
       perfect commit it fixes,	because	that commit is buried deeply in	a
       patch series. That is exactly what interactive rebase is	for: use it
       after plenty of "a"s and	"b"s, by rearranging and editing commits, and
       squashing multiple commits into one.

       Start it	with the last commit you want to retain	as-is:

	   git rebase -i <after-this-commit>

       An editor will be fired up with all the commits in your current branch
       (ignoring merge commits), which come after the given commit. You	can
       reorder the commits in this list	to your	heart's	content, and you can
       remove them. The	list looks more	or less	like this:

	   pick	deadbee	The oneline of this commit
	   pick	fa1afe1	The oneline of the next	commit
	   ...

       The oneline descriptions	are purely for your pleasure; git rebase will
       not look	at them	but at the commit names	("deadbee" and "fa1afe1" in
       this example), so do not	delete or edit the names.

       By replacing the	command	"pick" with the	command	"edit",	you can	tell
       git rebase to stop after	applying that commit, so that you can edit the
       files and/or the	commit message,	amend the commit, and continue
       rebasing.

       If you just want	to edit	the commit message for a commit, replace the
       command "pick" with the command "reword".

       To drop a commit, replace the command "pick" with "drop", or just
       delete the matching line.

       If you want to fold two or more commits into one, replace the command
       "pick" for the second and subsequent commits with "squash" or "fixup".
       If the commits had different authors, the folded	commit will be
       attributed to the author	of the first commit. The suggested commit
       message for the folded commit is	the concatenation of the commit
       messages	of the first commit and	of those with the "squash" command,
       but omits the commit messages of	commits	with the "fixup" command.

       git rebase will stop when "pick"	has been replaced with "edit" or when
       a command fails due to merge errors. When you are done editing and/or
       resolving conflicts you can continue with git rebase --continue.

       For example, if you want	to reorder the last 5 commits, such that what
       was HEAD~4 becomes the new HEAD.	To achieve that, you would call	git
       rebase like this:

	   $ git rebase	-i HEAD~5

       And move	the first patch	to the end of the list.

       You might want to preserve merges, if you have a	history	like this:

		      X
		       \
		    A---M---B
		   /
	   ---o---O---P---Q

       Suppose you want	to rebase the side branch starting at "A" to "Q". Make
       sure that the current HEAD is "B", and call

	   $ git rebase	-i -p --onto Q O

       Reordering and editing commits usually creates untested intermediate
       steps. You may want to check that your history editing did not break
       anything	by running a test, or at least recompiling at intermediate
       points in history by using the "exec" command (shortcut "x"). You may
       do so by	creating a todo	list like this one:

	   pick	deadbee	Implement feature XXX
	   fixup f1a5c00 Fix to	feature	XXX
	   exec	make
	   pick	c0ffeee	The oneline of the next	commit
	   edit	deadbab	The oneline of the commit after
	   exec	cd subdir; make	test
	   ...

       The interactive rebase will stop	when a command fails (i.e. exits with
       non-0 status) to	give you an opportunity	to fix the problem. You	can
       continue	with git rebase	--continue.

       The "exec" command launches the command in a shell (the one specified
       in $SHELL, or the default shell if $SHELL is not	set), so you can use
       shell features (like "cd", ">", ";" ...). The command is	run from the
       root of the working tree.

	   $ git rebase	-i --exec "make	test"

       This command lets you check that	intermediate commits are compilable.
       The todo	list becomes like that:

	   pick	5928aea	one
	   exec	make test
	   pick	04d0fda	two
	   exec	make test
	   pick	ba46169	three
	   exec	make test
	   pick	f4593f9	four
	   exec	make test

SPLITTING COMMITS
       In interactive mode, you	can mark commits with the action "edit".
       However,	this does not necessarily mean that git	rebase expects the
       result of this edit to be exactly one commit. Indeed, you can undo the
       commit, or you can add other commits. This can be used to split a
       commit into two:

       o   Start an interactive	rebase with git	rebase -i <commit>^, where
	   <commit> is the commit you want to split. In	fact, any commit range
	   will	do, as long as it contains that	commit.

       o   Mark	the commit you want to split with the action "edit".

       o   When	it comes to editing that commit, execute git reset HEAD^. The
	   effect is that the HEAD is rewound by one, and the index follows
	   suit. However, the working tree stays the same.

       o   Now add the changes to the index that you want to have in the first
	   commit. You can use git add (possibly interactively)	or git gui (or
	   both) to do that.

       o   Commit the now-current index	with whatever commit message is
	   appropriate now.

       o   Repeat the last two steps until your	working	tree is	clean.

       o   Continue the	rebase with git	rebase --continue.

       If you are not absolutely sure that the intermediate revisions are
       consistent (they	compile, pass the testsuite, etc.) you should use git
       stash to	stash away the not-yet-committed changes after each commit,
       test, and amend the commit if fixes are necessary.

RECOVERING FROM	UPSTREAM REBASE
       Rebasing	(or any	other form of rewriting) a branch that others have
       based work on is	a bad idea: anyone downstream of it is forced to
       manually	fix their history. This	section	explains how to	do the fix
       from the	downstream's point of view. The	real fix, however, would be to
       avoid rebasing the upstream in the first	place.

       To illustrate, suppose you are in a situation where someone develops a
       subsystem branch, and you are working on	a topic	that is	dependent on
       this subsystem. You might end up	with a history like the	following:

	       o---o---o---o---o---o---o---o---o  master
		    \
		     o---o---o---o---o	subsystem
				      \
				       *---*---*  topic

       If subsystem is rebased against master, the following happens:

	       o---o---o---o---o---o---o---o  master
		    \			    \
		     o---o---o---o---o	     o'--o'--o'--o'--o'	 subsystem
				      \
				       *---*---*  topic

       If you now continue development as usual, and eventually	merge topic to
       subsystem, the commits from subsystem will remain duplicated forever:

	       o---o---o---o---o---o---o---o  master
		    \			    \
		     o---o---o---o---o	     o'--o'--o'--o'--o'--M  subsystem
				      \				/
				       *---*---*-..........-*--*  topic

       Such duplicates are generally frowned upon because they clutter up
       history,	making it harder to follow. To clean things up,	you need to
       transplant the commits on topic to the new subsystem tip, i.e., rebase
       topic. This becomes a ripple effect: anyone downstream from topic is
       forced to rebase	too, and so on!

       There are two kinds of fixes, discussed in the following	subsections:

       Easy case: The changes are literally the	same.
	   This	happens	if the subsystem rebase	was a simple rebase and	had no
	   conflicts.

       Hard case: The changes are not the same.
	   This	happens	if the subsystem rebase	had conflicts, or used
	   --interactive to omit, edit,	squash,	or fixup commits; or if	the
	   upstream used one of	commit --amend,	reset, or filter-branch.

   The easy case
       Only works if the changes (patch	IDs based on the diff contents)	on
       subsystem are literally the same	before and after the rebase subsystem
       did.

       In that case, the fix is	easy because git rebase	knows to skip changes
       that are	already	present	in the new upstream. So	if you say (assuming
       you're on topic)

	       $ git rebase subsystem

       you will	end up with the	fixed history

	       o---o---o---o---o---o---o---o  master
					    \
					     o'--o'--o'--o'--o'	 subsystem
							      \
							       *---*---*  topic

   The hard case
       Things get more complicated if the subsystem changes do not exactly
       correspond to the ones before the rebase.

	   Note
	   While an "easy case recovery" sometimes appears to be successful
	   even	in the hard case, it may have unintended consequences. For
	   example, a commit that was removed via git rebase --interactive
	   will	be resurrected!

       The idea	is to manually tell git	rebase "where the old subsystem	ended
       and your	topic began", that is, what the	old merge-base between them
       was. You	will have to find a way	to name	the last commit	of the old
       subsystem, for example:

       o   With	the subsystem reflog: after git	fetch, the old tip of
	   subsystem is	at subsystem@{1}. Subsequent fetches will increase the
	   number. (See	git-reflog(1).)

       o   Relative to the tip of topic: knowing that your topic has three
	   commits, the	old tip	of subsystem must be topic~3.

       You can then transplant the old subsystem..topic	to the new tip by
       saying (for the reflog case, and	assuming you are on topic already):

	       $ git rebase --onto subsystem subsystem@{1}

       The ripple effect of a "hard case" recovery is especially bad: everyone
       downstream from topic will now have to perform a	"hard case" recovery
       too!

BUGS
       The todo	list presented by --preserve-merges --interactive does not
       represent the topology of the revision graph. Editing commits and
       rewording their commit messages should work fine, but attempts to
       reorder commits tend to produce counterintuitive	results.

       For example, an attempt to rearrange

	   1 --- 2 --- 3 --- 4 --- 5

       to

	   1 --- 2 --- 4 --- 3 --- 5

       by moving the "pick 4" line will	result in the following	history:

		   3
		  /
	   1 --- 2 --- 4 --- 5

GIT
       Part of the git(1) suite

NOTES
	1. revert-a-faulty-merge How-To
	   git-htmldocs/howto/revert-a-faulty-merge.html

Git 2.13.2			  06/24/2017			 GIT-REBASE(1)

NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | OPTIONS | MERGE STRATEGIES | NOTES | INTERACTIVE MODE | SPLITTING COMMITS | RECOVERING FROM UPSTREAM REBASE | BUGS | GIT | NOTES

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