GIT-RERERE(1)                                                    GIT-RERERE(1)



NAME
       git-rerere - Reuse recorded resolution of conflicted merges

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


DESCRIPTION
       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.


              Note

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



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


       clear  This resets 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>
              This resets the conflict resolutions which rerere has recorded
              for the current conflict in <pathspec>.


       diff   This displays 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.


       status Like diff, but this only prints the filenames that will be
              tracked for resolutions.


       gc     This prunes 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
       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.


GIT
       Part of the git(1) suite




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