NAME

       git-rerere - Reuse recorded resolution of conflicted merges

SYNOPSIS

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

       diff
           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.

       status
           Print paths with conflicts whose merge resolution rerere will record.

       remaining
           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.

       gc
           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

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

       [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

       Part of the git(1) suite