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> | --keep-base] [<upstream> [<branch>]]
git rebase [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>]
--root [<branch>]
git rebase (--continue|--skip|--abort|--quit|--edit-todo|--show-current-patch)
DESCRIPTION
If <branch> is specified, git rebase will perform an automatic git
switch <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.
Note
ORIG_HEAD is not guaranteed to still point to the previous branch
tip at the end of the rebase if other commands that write that
pseudo-ref (e.g. git reset) are used during the rebase. The
previous branch tip, however, is accessible using the reflog of the
current branch (i.e. @{1}, see gitrevisions(7)).
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 and warnings will be issued (if the merge
backend is used). 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
MODE OPTIONS
The options in this section cannot be used with any other option,
including not with each other:
--continue
Restart the rebasing process after having resolved a merge
conflict.
--skip
Restart the rebasing process by skipping the current patch.
--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. If a temporary stash entry was created using
--autostash, it will be saved to the stash list.
--edit-todo
Edit the todo list during an interactive rebase.
--show-current-patch
Show the current patch in an interactive rebase or when rebase is
stopped because of conflicts. This is the equivalent of git show
REBASE_HEAD.
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.
--keep-base
Set the starting point at which to create the new commits to the
merge base of <upstream> and <branch>. Running git rebase
--keep-base <upstream> <branch> is equivalent to running git rebase
--reapply-cherry-picks --no-fork-point --onto <upstream>...<branch>
<upstream> <branch>.
This option is useful in the case where one is developing a feature
on top of an upstream branch. While the feature is being worked on,
the upstream branch may advance and it may not be the best idea to
keep rebasing on top of the upstream but to keep the base commit
as-is. As the base commit is unchanged this option implies
--reapply-cherry-picks to avoid losing commits.
Although both this option and --fork-point find the merge base
between <upstream> and <branch>, this option uses the merge base as
the starting point on which new commits will be created, whereas
--fork-point uses the merge base to determine the set of commits
which will be rebased.
See also INCOMPATIBLE OPTIONS below.
<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.
--apply
Use applying strategies to rebase (calling git-am internally). This
option may become a no-op in the future once the merge backend
handles everything the apply one does.
See also INCOMPATIBLE OPTIONS below.
--empty=(drop|keep|stop)
How to handle commits that are not empty to start and are not clean
cherry-picks of any upstream commit, but which become empty after
rebasing (because they contain a subset of already upstream
changes):
drop
The commit will be dropped. This is the default behavior.
keep
The commit will be kept. This option is implied when --exec is
specified unless -i/--interactive is also specified.
stop, ask
The rebase will halt when the commit is applied, allowing you
to choose whether to drop it, edit files more, or just commit
the empty changes. This option is implied when -i/--interactive
is specified. ask is a deprecated synonym of stop.
Note that commits which start empty are kept (unless
--no-keep-empty is specified), and commits which are clean
cherry-picks (as determined by git log --cherry-mark ...) are
detected and dropped as a preliminary step (unless
--reapply-cherry-picks or --keep-base is passed).
See also INCOMPATIBLE OPTIONS below.
--no-keep-empty, --keep-empty
Do not keep commits that start empty before the rebase (i.e. that
do not change anything from its parent) in the result. The default
is to keep commits which start empty, since creating such commits
requires passing the --allow-empty override flag to git commit,
signifying that a user is very intentionally creating such a commit
and thus wants to keep it.
Usage of this flag will probably be rare, since you can get rid of
commits that start empty by just firing up an interactive rebase
and removing the lines corresponding to the commits you don't want.
This flag exists as a convenient shortcut, such as for cases where
external tools generate many empty commits and you want them all
removed.
For commits which do not start empty but become empty after
rebasing, see the --empty flag.
See also INCOMPATIBLE OPTIONS below.
--reapply-cherry-picks, --no-reapply-cherry-picks
Reapply all clean cherry-picks of any upstream commit instead of
preemptively dropping them. (If these commits then become empty
after rebasing, because they contain a subset of already upstream
changes, the behavior towards them is controlled by the --empty
flag.)
In the absence of --keep-base (or if --no-reapply-cherry-picks is
given), these commits will be automatically dropped. Because this
necessitates reading all upstream commits, this can be expensive in
repositories with a large number of upstream commits that need to
be read. When using the merge backend, warnings will be issued for
each dropped commit (unless --quiet is given). Advice will also be
issued unless advice.skippedCherryPicks is set to false (see git-
config(1)).
--reapply-cherry-picks allows rebase to forgo reading all upstream
commits, potentially improving performance.
See also INCOMPATIBLE OPTIONS below.
--allow-empty-message
No-op. Rebasing commits with an empty message used to fail and this
option would override that behavior, allowing commits with empty
messages to be rebased. Now commits with an empty message do not
cause rebasing to halt.
See also INCOMPATIBLE OPTIONS below.
-m, --merge
Using merging strategies to rebase (default).
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.
See also INCOMPATIBLE OPTIONS below.
-s <strategy>, --strategy=<strategy>
Use the given merge strategy, instead of the default ort. 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 empties all patches from the <branch>, which
makes little sense.
See also INCOMPATIBLE OPTIONS below.
-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 ort.
Note the reversal of ours and theirs as noted above for the -m
option.
See also INCOMPATIBLE OPTIONS below.
--rerere-autoupdate, --no-rerere-autoupdate
After the rerere mechanism reuses a recorded resolution on the
current conflict to update the files in the working tree, allow it
to also update the index with the result of resolution.
--no-rerere-autoupdate is a good way to double-check what rerere
did and catch potential mismerges, before committing the result to
the index with a separate git add.
-S[<keyid>], --gpg-sign[=<keyid>], --no-gpg-sign
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. --no-gpg-sign is useful to countermand
both commit.gpgSign configuration variable, and earlier --gpg-sign.
-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. Implies
--apply.
See also INCOMPATIBLE OPTIONS below.
--no-ff, --force-rebase, -f
Individually replay 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.
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).
--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 <upstream> or --keep-base is given on the command line, then the
default is --no-fork-point, otherwise the default is --fork-point.
See also rebase.forkpoint in git-config(1).
If your branch was based on <upstream> but <upstream> was rewound
and your branch contains commits which were dropped, this option
can be used with --keep-base in order to drop those commits from
your branch.
See also INCOMPATIBLE OPTIONS below.
--ignore-whitespace
Ignore whitespace differences when trying to reconcile differences.
Currently, each backend implements an approximation of this
behavior:
apply backend
When applying a patch, ignore changes in whitespace in context
lines. Unfortunately, this means that if the "old" lines being
replaced by the patch differ only in whitespace from the
existing file, you will get a merge conflict instead of a
successful patch application.
merge backend
Treat lines with only whitespace changes as unchanged when
merging. Unfortunately, this means that any patch hunks that
were intended to modify whitespace and nothing else will be
dropped, even if the other side had no changes that conflicted.
--whitespace=<option>
This flag is passed to the git apply program (see git-apply(1))
that applies the patch. Implies --apply.
See also INCOMPATIBLE OPTIONS below.
--committer-date-is-author-date
Instead of using the current time as the committer date, use the
author date of the commit being rebased as the committer date. This
option implies --force-rebase.
--ignore-date, --reset-author-date
Instead of using the author date of the original commit, use the
current time as the author date of the rebased commit. This option
implies --force-rebase.
See also INCOMPATIBLE OPTIONS below.
--signoff
Add a Signed-off-by trailer to all the rebased commits. Note that
if --interactive is given then only commits marked to be picked,
edited or reworded will have the trailer added.
See also INCOMPATIBLE OPTIONS below.
-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 commit hash prepended to the format.
See also INCOMPATIBLE OPTIONS below.
-r, --rebase-merges[=(rebase-cousins|no-rebase-cousins)],
--no-rebase-merges
By default, a rebase will simply drop merge commits from the todo
list, and put the rebased commits into a single, linear branch.
With --rebase-merges, the rebase will instead try to preserve the
branching structure within the commits that are to be rebased, by
recreating the merge commits. Any resolved merge conflicts or
manual amendments in these merge commits will have to be
resolved/re-applied manually. --no-rebase-merges can be used to
countermand both the rebase.rebaseMerges config option and a
previous --rebase-merges.
When rebasing merges, there are two modes: rebase-cousins and
no-rebase-cousins. If the mode is not specified, it defaults to
no-rebase-cousins. In no-rebase-cousins mode, commits which do not
have <upstream> as direct ancestor will keep their original branch
point, i.e. commits that would be excluded by git-log(1)'s
--ancestry-path option will keep their original ancestry by
default. In rebase-cousins mode, such commits are instead rebased
onto <upstream> (or <onto>, if specified).
It is currently only possible to recreate the merge commits using
the ort merge strategy; different merge strategies can be used only
via explicit exec git merge -s <strategy> [...] commands.
See also REBASING MERGES and INCOMPATIBLE OPTIONS 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.
Any command that fails will interrupt the rebase, with exit code 1.
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.
See also INCOMPATIBLE OPTIONS below.
--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.
See also INCOMPATIBLE OPTIONS below.
--autosquash, --no-autosquash
Automatically squash commits with specially formatted messages into
previous commits being rebased. If a commit message starts with
"squash! ", "fixup! " or "amend! ", the remainder of the subject
line is taken as a commit specifier, which matches a previous
commit if it matches the subject line or the hash of that commit.
If no commit matches fully, matches of the specifier with the start
of commit subjects are considered.
In the rebase todo list, the actions of squash, fixup and amend
commits are changed from pick to squash, fixup or fixup -C,
respectively, and they are moved right after the commit they
modify. The --interactive option can be used to review and edit the
todo list before proceeding.
The recommended way to create commits with squash markers is by
using the --squash, --fixup, --fixup=amend: or --fixup=reword:
options of git-commit(1), which take the target commit as an
argument and automatically fill in the subject line of the new
commit from that.
Setting configuration variable rebase.autoSquash to true enables
auto-squashing by default for interactive rebase. The
--no-autosquash option can be used to override that setting.
See also INCOMPATIBLE OPTIONS below.
--autostash, --no-autostash
Automatically create a temporary stash entry 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.
--reschedule-failed-exec, --no-reschedule-failed-exec
Automatically reschedule exec commands that failed. This only makes
sense in interactive mode (or when an --exec option was provided).
This option applies once a rebase is started. It is preserved for
the whole rebase based on, in order, the command line option
provided to the initial git rebase, the rebase.rescheduleFailedExec
configuration (see git-config(1) or "CONFIGURATION" below), or it
defaults to false.
Recording this option for the whole rebase is a convenience
feature. Otherwise an explicit --no-reschedule-failed-exec at the
start would be overridden by the presence of a
rebase.rescheduleFailedExec=true configuration when git rebase
--continue is invoked. Currently, you cannot pass
--[no-]reschedule-failed-exec to git rebase --continue.
--update-refs, --no-update-refs
Automatically force-update any branches that point to commits that
are being rebased. Any branches that are checked out in a worktree
are not updated in this way.
If the configuration variable rebase.updateRefs is set, then this
option can be used to override and disable this setting.
See also INCOMPATIBLE OPTIONS below.
INCOMPATIBLE OPTIONS
The following options:
o --apply
o --whitespace
o -C
are incompatible with the following options:
o --merge
o --strategy
o --strategy-option
o --autosquash
o --rebase-merges
o --interactive
o --exec
o --no-keep-empty
o --empty=
o --[no-]reapply-cherry-picks when used without --keep-base
o --update-refs
o --root when used without --onto
In addition, the following pairs of options are incompatible:
o --keep-base and --onto
o --keep-base and --root
o --fork-point and --root
BEHAVIORAL DIFFERENCES
git rebase has two primary backends: apply and merge. (The apply
backend used to be known as the am backend, but the name led to
confusion as it looks like a verb instead of a noun. Also, the merge
backend used to be known as the interactive backend, but it is now used
for non-interactive cases as well. Both were renamed based on
lower-level functionality that underpinned each.) There are some subtle
differences in how these two backends behave:
Empty commits
The apply backend unfortunately drops intentionally empty commits, i.e.
commits that started empty, though these are rare in practice. It also
drops commits that become empty and has no option for controlling this
behavior.
The merge backend keeps intentionally empty commits by default (though
with -i they are marked as empty in the todo list editor, or they can
be dropped automatically with --no-keep-empty).
Similar to the apply backend, by default the merge backend drops
commits that become empty unless -i/--interactive is specified (in
which case it stops and asks the user what to do). The merge backend
also has an --empty=(drop|keep|stop) option for changing the behavior
of handling commits that become empty.
Directory rename detection
Due to the lack of accurate tree information (arising from constructing
fake ancestors with the limited information available in patches),
directory rename detection is disabled in the apply backend. Disabled
directory rename detection means that if one side of history renames a
directory and the other adds new files to the old directory, then the
new files will be left behind in the old directory without any warning
at the time of rebasing that you may want to move these files into the
new directory.
Directory rename detection works with the merge backend to provide you
warnings in such cases.
Context
The apply backend works by creating a sequence of patches (by calling
format-patch internally), and then applying the patches in sequence
(calling am internally). Patches are composed of multiple hunks, each
with line numbers, a context region, and the actual changes. The line
numbers have to be taken with some fuzz, since the other side will
likely have inserted or deleted lines earlier in the file. The context
region is meant to help find how to adjust the line numbers in order to
apply the changes to the right lines. However, if multiple areas of the
code have the same surrounding lines of context, the wrong one can be
picked. There are real-world cases where this has caused commits to be
reapplied incorrectly with no conflicts reported. Setting diff.context
to a larger value may prevent such types of problems, but increases the
chance of spurious conflicts (since it will require more lines of
matching context to apply).
The merge backend works with a full copy of each relevant file,
insulating it from these types of problems.
Labelling of conflicts markers
When there are content conflicts, the merge machinery tries to annotate
each side's conflict markers with the commits where the content came
from. Since the apply backend drops the original information about the
rebased commits and their parents (and instead generates new fake
commits based off limited information in the generated patches), those
commits cannot be identified; instead it has to fall back to a commit
summary. Also, when merge.conflictStyle is set to diff3 or zdiff3, the
apply backend will use "constructed merge base" to label the content
from the merge base, and thus provide no information about the merge
base commit whatsoever.
The merge backend works with the full commits on both sides of history
and thus has no such limitations.
Hooks
The apply backend has not traditionally called the post-commit hook,
while the merge backend has. Both have called the post-checkout hook,
though the merge backend has squelched its output. Further, both
backends only call the post-checkout hook with the starting point
commit of the rebase, not the intermediate commits nor the final
commit. In each case, the calling of these hooks was by accident of
implementation rather than by design (both backends were originally
implemented as shell scripts and happened to invoke other commands like
git checkout or git commit that would call the hooks). Both backends
should have the same behavior, though it is not entirely clear which,
if any, is correct. We will likely make rebase stop calling either of
these hooks in the future.
Interruptability
The apply backend has safety problems with an ill-timed interrupt; if
the user presses Ctrl-C at the wrong time to try to abort the rebase,
the rebase can enter a state where it cannot be aborted with a
subsequent git rebase --abort. The merge backend does not appear to
suffer from the same shortcoming. (See
https://lore.kernel.org/git/20200207132152.GC2868@szeder.dev/ for
details.)
Commit Rewording
When a conflict occurs while rebasing, rebase stops and asks the user
to resolve. Since the user may need to make notable changes while
resolving conflicts, after conflicts are resolved and the user has run
git rebase --continue, the rebase should open an editor and ask the
user to update the commit message. The merge backend does this, while
the apply backend blindly applies the original commit message.
Miscellaneous differences
There are a few more behavioral differences that most folks would
probably consider inconsequential but which are mentioned for
completeness:
o Reflog: The two backends will use different wording when describing
the changes made in the reflog, though both will make use of the
word "rebase".
o Progress, informational, and error messages: The two backends
provide slightly different progress and informational messages.
Also, the apply backend writes error messages (such as "Your files
would be overwritten...") to stdout, while the merge backend writes
them to stderr.
o State directories: The two backends keep their state in different
directories under .git/
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.
ort
This is the default merge strategy when pulling or merging one
branch. This strategy 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 strategy
can detect and handle merges involving renames. It does not make
use of detected copies. The name for this algorithm is an acronym
("Ostensibly Recursive's Twin") and came from the fact that it was
written as a replacement for the previous default algorithm,
recursive.
The ort 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 in 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; note that, unlike ours, there is
no theirs merge strategy to confuse this merge option with.
ignore-space-change, ignore-all-space, ignore-space-at-eol,
ignore-cr-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, --ignore-space-at-eol, and
--ignore-cr-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.
find-renames[=<n>]
Turn on rename detection, optionally setting the similarity
threshold. This is the default. This overrides the
merge.renames configuration variable. 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.
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. It does not make use of detected
copies. This was the default strategy for resolving two heads from
Git v0.99.9k until v2.33.0.
The recursive strategy takes the same options as ort. However,
there are three additional options that ort ignores (not documented
above) that are potentially useful with the recursive strategy:
patience
Deprecated synonym for diff-algorithm=patience.
diff-algorithm=[patience|minimal|histogram|myers]
Use a different diff algorithm while merging, 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. Note that ort specifically uses
diff-algorithm=histogram, while recursive defaults to the
diff.algorithm config setting.
no-renames
Turn off rename detection. This overrides the merge.renames
configuration variable. See also git-diff(1) --no-renames.
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. It does
not handle renames.
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 ort 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, ort),
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 rebase 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.
To interrupt the rebase (just like an "edit" command would do, but
without cherry-picking any commit first), use the "break" command.
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 first
commit's message with those identified by "squash" commands, omitting
the messages of commits identified by "fixup" commands, unless "fixup
-c" is used. In that case the suggested commit message is only the
message of the "fixup -c" commit, and an editor is opened allowing you
to edit the message. The contents (patch) of the "fixup -c" commit are
still incorporated into the folded commit. If there is more than one
"fixup -c" commit, the message from the final one is used. You can also
use "fixup -C" to get the same behavior as "fixup -c" except without
opening an editor.
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 recreate merge commits, e.g. 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 -r --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 default one,
usually /bin/sh), 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 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 a full history
rewriting command like filter-repo[2].
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 (unless
--reapply-cherry-picks is given). 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!
REBASING MERGES
The interactive rebase command was originally designed to handle
individual patch series. As such, it makes sense to exclude merge
commits from the todo list, as the developer may have merged the
then-current master while working on the branch, only to rebase all the
commits onto master eventually (skipping the merge commits).
However, there are legitimate reasons why a developer may want to
recreate merge commits: to keep the branch structure (or "commit
topology") when working on multiple, inter-related branches.
In the following example, the developer works on a topic branch that
refactors the way buttons are defined, and on another topic branch that
uses that refactoring to implement a "Report a bug" button. The output
of git log --graph --format=%s -5 may look like this:
* Merge branch 'report-a-bug'
|\
| * Add the feedback button
* | Merge branch 'refactor-button'
|\ \
| |/
| * Use the Button class for all buttons
| * Extract a generic Button class from the DownloadButton one
The developer might want to rebase those commits to a newer master
while keeping the branch topology, for example when the first topic
branch is expected to be integrated into master much earlier than the
second one, say, to resolve merge conflicts with changes to the
DownloadButton class that made it into master.
This rebase can be performed using the --rebase-merges option. It will
generate a todo list looking like this:
label onto
# Branch: refactor-button
reset onto
pick 123456 Extract a generic Button class from the DownloadButton one
pick 654321 Use the Button class for all buttons
label refactor-button
# Branch: report-a-bug
reset refactor-button # Use the Button class for all buttons
pick abcdef Add the feedback button
label report-a-bug
reset onto
merge -C a1b2c3 refactor-button # Merge 'refactor-button'
merge -C 6f5e4d report-a-bug # Merge 'report-a-bug'
In contrast to a regular interactive rebase, there are label, reset and
merge commands in addition to pick ones.
The label command associates a label with the current HEAD when that
command is executed. These labels are created as worktree-local refs
(refs/rewritten/<label>) that will be deleted when the rebase finishes.
That way, rebase operations in multiple worktrees linked to the same
repository do not interfere with one another. If the label command
fails, it is rescheduled immediately, with a helpful message how to
proceed.
The reset command resets the HEAD, index and worktree to the specified
revision. It is similar to an exec git reset --hard <label>, but
refuses to overwrite untracked files. If the reset command fails, it is
rescheduled immediately, with a helpful message how to edit the todo
list (this typically happens when a reset command was inserted into the
todo list manually and contains a typo).
The merge command will merge the specified revision(s) into whatever is
HEAD at that time. With -C <original-commit>, the commit message of the
specified merge commit will be used. When the -C is changed to a
lower-case -c, the message will be opened in an editor after a
successful merge so that the user can edit the message.
If a merge command fails for any reason other than merge conflicts
(i.e. when the merge operation did not even start), it is rescheduled
immediately.
By default, the merge command will use the ort merge strategy for
regular merges, and octopus for octopus merges. One can specify a
default strategy for all merges using the --strategy argument when
invoking rebase, or can override specific merges in the interactive
list of commands by using an exec command to call git merge explicitly
with a --strategy argument. Note that when calling git merge explicitly
like this, you can make use of the fact that the labels are
worktree-local refs (the ref refs/rewritten/onto would correspond to
the label onto, for example) in order to refer to the branches you want
to merge.
Note: the first command (label onto) labels the revision onto which the
commits are rebased; The name onto is just a convention, as a nod to
the --onto option.
It is also possible to introduce completely new merge commits from
scratch by adding a command of the form merge <merge-head>. This form
will generate a tentative commit message and always open an editor to
let the user edit it. This can be useful e.g. when a topic branch turns
out to address more than a single concern and wants to be split into
two or even more topic branches. Consider this todo list:
pick 192837 Switch from GNU Makefiles to CMake
pick 5a6c7e Document the switch to CMake
pick 918273 Fix detection of OpenSSL in CMake
pick afbecd http: add support for TLS v1.3
pick fdbaec Fix detection of cURL in CMake on Windows
The one commit in this list that is not related to CMake may very well
have been motivated by working on fixing all those bugs introduced by
switching to CMake, but it addresses a different concern. To split this
branch into two topic branches, the todo list could be edited like
this:
label onto
pick afbecd http: add support for TLS v1.3
label tlsv1.3
reset onto
pick 192837 Switch from GNU Makefiles to CMake
pick 918273 Fix detection of OpenSSL in CMake
pick fdbaec Fix detection of cURL in CMake on Windows
pick 5a6c7e Document the switch to CMake
label cmake
reset onto
merge tlsv1.3
merge cmake
CONFIGURATION
Everything below this line in this section is selectively included from
the git-config(1) documentation. The content is the same as what's
found there:
rebase.backend
Default backend to use for rebasing. Possible choices are apply or
merge. In the future, if the merge backend gains all remaining
capabilities of the apply backend, this setting may become unused.
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 the git-rebase(1) by
default for interactive mode. This can be overridden with the
--no-autosquash option.
rebase.autoStash
When set to true, automatically create a temporary stash entry
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. This option can be
overridden by the --no-autostash and --autostash options of git-
rebase(1). Defaults to false.
rebase.updateRefs
If set to true enable --update-refs option by default.
rebase.missingCommitsCheck
If set to "warn", git rebase -i will print a warning if some
commits are removed (e.g. a line was deleted), however the rebase
will still proceed. If set to "error", it will print the previous
warning and stop the rebase, git rebase --edit-todo can then be
used to correct the error. If set to "ignore", no checking is done.
To drop a commit without warning or error, use the drop command in
the todo list. Defaults to "ignore".
rebase.instructionFormat
A format string, as specified in git-log(1), to be used for the
todo list during an interactive rebase. The format will
automatically have the commit hash prepended to the format.
rebase.abbreviateCommands
If set to true, git rebase will use abbreviated command names in
the todo list resulting in something like this:
p deadbee The oneline of the commit
p fa1afe1 The oneline of the next commit
...
instead of:
pick deadbee The oneline of the commit
pick fa1afe1 The oneline of the next commit
...
Defaults to false.
rebase.rescheduleFailedExec
Automatically reschedule exec commands that failed. This only makes
sense in interactive mode (or when an --exec option was provided).
This is the same as specifying the --reschedule-failed-exec option.
rebase.forkPoint
If set to false set --no-fork-point option by default.
rebase.rebaseMerges
Whether and how to set the --rebase-merges option by default. Can
be rebase-cousins, no-rebase-cousins, or a boolean. Setting to true
or to no-rebase-cousins is equivalent to
--rebase-merges=no-rebase-cousins, setting to rebase-cousins is
equivalent to --rebase-merges=rebase-cousins, and setting to false
is equivalent to --no-rebase-merges. Passing --rebase-merges on the
command line, with or without an argument, overrides any
rebase.rebaseMerges configuration.
rebase.maxLabelLength
When generating label names from commit subjects, truncate the
names to this length. By default, the names are truncated to a
little less than NAME_MAX (to allow e.g. .lock files to be written
for the corresponding loose refs).
sequence.editor
Text editor used by git rebase -i for editing the rebase
instruction file. The value is meant to be interpreted by the shell
when it is used. It can be overridden by the GIT_SEQUENCE_EDITOR
environment variable. When not configured, the default commit
message editor is used instead.
GIT
Part of the git(1) suite
NOTES
1. revert-a-faulty-merge How-To
git-htmldocs/howto/revert-a-faulty-merge.html
2. filter-repo
https://github.com/newren/git-filter-repo
Git 2.45.0 2024-04-29 git-rebase(1)
git 2.45.0 - Generated Wed May 8 18:35:38 CDT 2024