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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.
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.useBuiltin
Unused configuration variable. Used in Git versions 2.20 and 2.21 as an escape hatch to enable the
legacy shellscript implementation of rebase. Now the built-in rewrite of it in C is always used.
Setting this will emit a warning, to alert any remaining users that setting this now does nothing.
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
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.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 long 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.
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> <branch>.
Running git rebase --keep-base <upstream> <branch> is equivalent to running git rebase --onto
<upstream>... <upstream>.
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.
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.
--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.
See also INCOMPATIBLE OPTIONS below.
--allow-empty-message
By default, rebasing commits with an empty message will fail. This option overrides that behavior,
allowing commits with empty messages to be rebased.
See also INCOMPATIBLE OPTIONS below.
--skip
Restart the rebasing process by skipping the current patch.
--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.
-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.
See also INCOMPATIBLE OPTIONS below.
-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 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 recursive. Note the reversal of ours and theirs as noted above for the -m
option.
See also INCOMPATIBLE OPTIONS below.
--rerere-autoupdate, --no-rerere-autoupdate
Allow the rerere mechanism to update the index with the result of auto-conflict resolution if
possible.
-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.
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 either <upstream> or --root is given on the command line, then the default is --no-fork-point,
otherwise the default is --fork-point.
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.
--ignore-whitespace, --whitespace=<option>
These flag are passed to the git apply program (see git-apply(1)) that applies the patch.
See also INCOMPATIBLE OPTIONS below.
--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)).
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 long commit hash prepended to the format.
See also INCOMPATIBLE OPTIONS below.
-r, --rebase-merges[=(rebase-cousins|no-rebase-cousins)]
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.
By default, or when no-rebase-cousins was specified, 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. If the rebase-cousins mode is
turned on, such commits are instead rebased onto <upstream> (or <onto>, if specified).
The --rebase-merges mode is similar in spirit to the deprecated --preserve-merges but works with
interactive rebases, where commits can be reordered, inserted and dropped at will.
It is currently only possible to recreate the merge commits using the recursive 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.
-p, --preserve-merges
[DEPRECATED: use --rebase-merges instead] 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).
See also 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. 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.
See also INCOMPATIBLE OPTIONS below.
--autosquash, --no-autosquash
When the commit log message begins with "squash! ..." (or "fixup! ..."), and there is already a
commit in the todo list that matches 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). A commit matches the ... if the commit
subject matches, or if the ... refers to the commit’s hash. As a fall-back, partial matches of the
commit subject work, too. The recommended way to create fixup/squash commits is by using the
--fixup/--squash options of git-commit(1).
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.
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).
INCOMPATIBLE OPTIONS
The following options:
• --committer-date-is-author-date
• --ignore-date
• --whitespace
• --ignore-whitespace
• -C
are incompatible with the following options:
• --merge
• --strategy
• --strategy-option
• --allow-empty-message
• --[no-]autosquash
• --rebase-merges
• --preserve-merges
• --interactive
• --exec
• --keep-empty
• --edit-todo
• --root when used in combination with --onto
In addition, the following pairs of options are incompatible:
• --preserve-merges and --interactive
• --preserve-merges and --signoff
• --preserve-merges and --rebase-merges
• --keep-base and --onto
• --keep-base and --root
BEHAVIORAL DIFFERENCES
There are some subtle differences how the backends behave.
Empty commits
The am backend drops any "empty" commits, regardless of whether the commit started empty (had no changes
relative to its parent to start with) or ended empty (all changes were already applied upstream in other
commits).
The interactive backend drops commits by default that started empty and halts if it hits a commit that
ended up empty. The --keep-empty option exists for the interactive backend to allow it to keep commits
that started empty.
Directory rename detection
Directory rename heuristics are enabled in the merge and interactive backends. Due to the lack of
accurate tree information, directory rename detection is disabled in the am backend.
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, but currently
cannot make use of detected copies. 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 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.
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, 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.
• If their version only introduces whitespace changes to a line, our version is used;
• If our version introduces whitespace changes but their version includes a substantial change,
their version is used;
• 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. This overrides the merge.renames configuration variable. See also git-
diff(1) --no-renames.
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.
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.
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 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 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 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:
• 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.
• Mark the commit you want to split with the action "edit".
• 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.
• 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.
• Commit the now-current index with whatever commit message is appropriate now.
• Repeat the last two steps until your working tree is clean.
• 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. 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:
• 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).)
• 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.
At this time, the merge command will always use the recursive merge strategy for regular merges, and
octopus for octopus merges, with no way to choose a different one. To work around this, an exec command
can be used to call git merge explicitly, using the fact that the labels are worktree-local refs (the ref
refs/rewritten/onto would correspond to the label onto, for example).
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
BUGS
The todo list presented by the deprecated --preserve-merges --interactive does not represent the topology
of the revision graph (use --rebase-merges instead). Editing commits and rewording their commit messages
should work fine, but attempts to reorder commits tend to produce counterintuitive results. Use
--rebase-merges in such scenarios instead.
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
file:///usr/share/doc/git/html/howto/revert-a-faulty-merge.html
2. filter-repo
https://github.com/newren/git-filter-repo