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

       git-rerere - Reuse recorded resolution of conflicted merges

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

       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.

       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 record.

           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.

       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

                   $ 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 variable).

       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

       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.

       Part of the git(1) suite

Git                      08/29/2012                     GIT-RERERE(1)