GIT-RERERE(1)                    Git Manual                    GIT-RERERE(1)

NAME         top

       git-rerere - Reuse recorded resolution of conflicted merges

SYNOPSIS         top

       git rerere [clear|forget <pathspec>|diff|remaining|status|gc]

DESCRIPTION         top

       In a workflow employing relatively long lived topic branches, the
       developer sometimes needs to resolve the same conflicts over and over
       again until the topic branches are done (either merged to the
       "release" branch, or sent out and accepted upstream).

       This command assists the developer in this process by recording
       conflicted automerge results and corresponding hand resolve results
       on the initial manual merge, and applying previously recorded hand
       resolutions to their corresponding automerge results.

           You need to set the configuration variable rerere.enabled in
           order to enable this command.

COMMANDS         top

       Normally, git rerere is run without arguments or user-intervention.
       However, it has several commands that allow it to interact with its
       working state.

           Reset the metadata used by rerere if a merge resolution is to be
           aborted. Calling git am [--skip|--abort] or git rebase
           [--skip|--abort] will automatically invoke this command.

       forget <pathspec>
           Reset the conflict resolutions which rerere has recorded for the
           current conflict in <pathspec>.

           Display diffs for the current state of the resolution. It is
           useful for tracking what has changed while the user is resolving
           conflicts. Additional arguments are passed directly to the system
           diff command installed in PATH.

           Print paths with conflicts whose merge resolution rerere will

           Print paths with conflicts that have not been autoresolved by
           rerere. This includes paths whose resolutions cannot be tracked
           by rerere, such as conflicting submodules.

           Prune records of conflicted merges that occurred a long time ago.
           By default, unresolved conflicts older than 15 days and resolved
           conflicts older than 60 days are pruned. These defaults are
           controlled via the gc.rerereUnresolved and gc.rerereResolved
           configuration variables respectively.

DISCUSSION         top

       When your topic branch modifies an overlapping area that your master
       branch (or upstream) touched since your topic branch forked from it,
       you may want to test it with the latest master, even before your
       topic branch is ready to be pushed upstream:

                         o---*---o topic
               o---o---o---*---o---o master

       For such a test, you need to merge master and topic somehow. One way
       to do it is to pull master into the topic branch:

                   $ git checkout topic
                   $ git merge master

                         o---*---o---+ topic
                        /           /
               o---o---o---*---o---o master

       The commits marked with * touch the same area in the same file; you
       need to resolve the conflicts when creating the commit marked with +.
       Then you can test the result to make sure your work-in-progress still
       works with what is in the latest master.

       After this test merge, there are two ways to continue your work on
       the topic. The easiest is to build on top of the test merge commit +,
       and when your work in the topic branch is finally ready, pull the
       topic branch into master, and/or ask the upstream to pull from you.
       By that time, however, the master or the upstream might have been
       advanced since the test merge +, in which case the final commit graph
       would look like this:

                   $ git checkout topic
                   $ git merge master
                   $ ... work on both topic and master branches
                   $ git checkout master
                   $ git merge topic

                         o---*---o---+---o---o topic
                        /           /         \
               o---o---o---*---o---o---o---o---+ master

       When your topic branch is long-lived, however, your topic branch
       would end up having many such "Merge from master" commits on it,
       which would unnecessarily clutter the development history. Readers of
       the Linux kernel mailing list may remember that Linus complained
       about such too frequent test merges when a subsystem maintainer asked
       to pull from a branch full of "useless merges".

       As an alternative, to keep the topic branch clean of test merges, you
       could blow away the test merge, and keep building on top of the tip
       before the test merge:

                   $ git checkout topic
                   $ git merge master
                   $ git reset --hard HEAD^ ;# rewind the test merge
                   $ ... work on both topic and master branches
                   $ git checkout master
                   $ git merge topic

                         o---*---o-------o---o topic
                        /                     \
               o---o---o---*---o---o---o---o---+ master

       This would leave only one merge commit when your topic branch is
       finally ready and merged into the master branch. This merge would
       require you to resolve the conflict, introduced by the commits marked
       with *. However, this conflict is often the same conflict you
       resolved when you created the test merge you blew away. git rerere
       helps you resolve this final conflicted merge using the information
       from your earlier hand resolve.

       Running the git rerere command immediately after a conflicted
       automerge records the conflicted working tree files, with the usual
       conflict markers <<<<<<<, =======, and >>>>>>> in them. Later, after
       you are done resolving the conflicts, running git rerere again will
       record the resolved state of these files. Suppose you did this when
       you created the test merge of master into the topic branch.

       Next time, after seeing the same conflicted automerge, running git
       rerere will perform a three-way merge between the earlier conflicted
       automerge, the earlier manual resolution, and the current conflicted
       automerge. If this three-way merge resolves cleanly, the result is
       written out to your working tree file, so you do not have to manually
       resolve it. Note that git rerere leaves the index file alone, so you
       still need to do the final sanity checks with git diff (or git diff
       -c) and git add when you are satisfied.

       As a convenience measure, git merge automatically invokes git rerere
       upon exiting with a failed automerge and git rerere records the hand
       resolve when it is a new conflict, or reuses the earlier hand resolve
       when it is not. git commit also invokes git rerere when committing a
       merge result. What this means is that you do not have to do anything
       special yourself (besides enabling the rerere.enabled config

       In our example, when you do the test merge, the manual resolution is
       recorded, and it will be reused when you do the actual merge later
       with the updated master and topic branch, as long as the recorded
       resolution is still applicable.

       The information git rerere records is also used when running git
       rebase. After blowing away the test merge and continuing development
       on the topic branch:

                         o---*---o-------o---o topic
               o---o---o---*---o---o---o---o   master

                   $ git rebase master topic

                                             o---*---o-------o---o topic
               o---o---o---*---o---o---o---o   master

       you could run git rebase master topic, to bring yourself up to date
       before your topic is ready to be sent upstream. This would result in
       falling back to a three-way merge, and it would conflict the same way
       as the test merge you resolved earlier. git rerere will be run by git
       rebase to help you resolve this conflict.

       [NOTE] git rerere relies on the conflict markers in the file to
       detect the conflict. If the file already contains lines that look the
       same as lines with conflict markers, git rerere may fail to record a
       conflict resolution. To work around this, the conflict-marker-size
       setting in gitattributes(5) can be used.

GIT         top

       Part of the git(1) suite

COLOPHON         top

       This page is part of the git (Git distributed version control system)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual page,
       see ⟨⟩.  This page was obtained from the
       project's upstream Git repository ⟨⟩ on
       2018-10-29.  (At that time, the date of the most recent commit that
       was found in the repository was 2018-10-26.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Git           10/28/2018                    GIT-RERERE(1)

Pages that refer to this page: git(1)git-config(1)git-gc(1)