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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

       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 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 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.

       Part of the git(1) suite

Git 1.8.3                                        05/24/2013                                    GIT-RERERE(1)

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