git rebase

REBASE

git rebase -i

在feature分支上执行: git rebase master

这句命令的意识是：以master为基础，将feature分支上的修改增加到master分支上，并生成新的版本。

git rebase -i d2bf14b495fe57583371be8d0a48c927a2da7eb9 7fc6da429881c5bca2705f61aac0e3a1a3c0b1c7

• p, pick: 保留该 commit。
• r, reword: 保留该 commit，可以修改 commit 的注释。
• e, eidt: 保留该 commit，但停下来修改该 commit （不仅仅是注释），可以用来解决 merge 冲突。
• s, squash: 将该 commit 和 前面一个 commit 合并
• f, fixup: 将该 commit 和 前面一个 commit 合并，但不保留该提交的注释信息
• x, exec: 执行 shell 命令
• d, drop: 丢弃该 commit。

git rebase

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

也就是说
当前在topic时

git rebase master
git rebase master topic

等价

执行上述命令的过程为：

1. 切换到to-branch分支；
2. 将to-branch中比upstream-branch多的commit先撤销掉，并将这些commit放在一块临时存储区（.git/rebase）；
3. 将upstream-branch中比to-branch多的commit应用到to-branch上，此刻to-branch和upstream-branch的代码状态一致；
4. 将存放的临时存储区的commit重新应用到to-branch上；
   结束。
   执行完上述第3步后，to-branch的代码状态已经改变，接着执行第4步时则可能会产生合并冲突。

冲突解决

git rebase  

解决合并冲突几个常见的办法是：

1. 手动编辑冲突文件，手动删除或者保留冲突的代码；

2. 对于“both added”、“both deleted”、“both modified”等类型的冲突，若想完整地保留某一方的修改可以执行git checkout --ours(或者–theirs) <文件名>来选择想要保留的版本。

   需要注意的是由于git rebase 是先撤销再应用commit，所以这里的ours指的是upstream-branch，theirs指的是我们将要应用的临时commit。

   their 就是当前处理的commit

3. 对于“added by us/them”、“deleted by us/them”等类型的冲突需要使用git rm 和git add 来删除/添加file。在此过程中需要特别注意谁是us，谁是them。

冲突解决完之后，使用git add 来标记冲突已解决，最后执行git rebase --continue继续。如果中间遇到某个补丁不需要应用，可以用git rebase --skip

git rebase document

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 ] [--onto ]
               [ []]
       git rebase [-i | --interactive] [options] [--exec ] [--onto ]
               --root []
       git rebase --continue | --skip | --abort | --quit | --edit-todo | --show-current-patch

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

       If  is not specified, the upstream configured in
       branch..remote and branch..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
        are saved to a temporary area. This is the same set of
       commits that would be shown by git log ..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 , or  if the --onto
       option was supplied. This has the exact same effect as git reset --hard
        (or ). 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.. 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  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 
       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 

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

           git rebase --continue

       Alternatively, you can undo the git rebase with

           git rebase --abort

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

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

       rebase.autoStash
           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.

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

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

       
           Upstream branch to compare against. May be any valid commit, not
           just an existing branch name. Defaults to the configured upstream
           for the current 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  was provided when the rebase operation was started,
           then HEAD will be reset to . 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.

       --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.

       --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  branch. Because of this,
           when a merge conflict happens, the side reported as ours is the
           so-far rebased series, starting with , and theirs is the
           working branch. In other words, the sides are swapped.

       -s , --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  branch using the given strategy, using the
           ours strategy simply discards all patches from the , which
           makes little sense.

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

       -S[], --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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

           or by giving more than one --exec:

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

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

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

       --root
           Rebase all commits reachable from , instead of limiting
           them with an . This allows you to rebase the root
           commit(s) on a branch. When used with --onto, it will skip changes
           already contained in  (instead of ) 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  as parent instead.

       --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).

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

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

       --autostash, --no-autostash
           Automatically create a temporary stash 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.

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

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

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

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

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

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

           The recursive strategy can take the following options:

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

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

           theirs
               This is the opposite of ours; 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. See also git-diff(1) --no-renames.

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

           rename-threshold=
               Deprecated synonym for find-renames=.

           subtree[=]
               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,  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 

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

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

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

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

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

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

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

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

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

           $ git rebase -i HEAD~5

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

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

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

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

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

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

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

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

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

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

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

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

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

       ·   Start an interactive rebase with git rebase -i ^, where
            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 filter-branch.

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

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

               $ git rebase subsystem

       you will end up with the fixed history

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

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

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

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

       ·   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!

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

       For example, an attempt to rearrange

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

       to

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

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

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

GIT
       Part of the git(1) suite

NOTES
        1. revert-a-faulty-merge How-To
           file:///usr/share/doc/git/html/howto/revert-a-faulty-merge.html

Git 2.17.1                        11/26/2018                     GIT-REBASE(1)