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+git-rerere(1)
+=============
+
+NAME
+----
+git-rerere - Reuse recorded resolve
+
+SYNOPSIS
+--------
+'git-rerere'
+
+
+DESCRIPTION
+-----------
+
+In a workflow that employs relatively long lived topic branches,
+the developer sometimes needs to resolve the same conflict over
+and over again until the topic branches are done (either merged
+to the "release" branch, or sent out and accepted upstream).
+
+This command helps this process by recording conflicted
+automerge results and corresponding hand-resolve results on the
+initial manual merge, and later by noticing the same automerge
+results and applying the previously recorded hand resolution.
+
+[NOTE]
+You need to create `$GIT_DIR/rr-cache` directory to enable this
+command.
+
+DISCUSSION
+----------
+
+When your topic branch modifies 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 pull . 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 pull . master
+ $ ... work on both topic and master branches
+ $ git checkout master
+ $ git pull . 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 pull . master
+ $ git reset --hard HEAD^ ;# rewind the test merge
+ $ ... work on both topic and master branches
+ $ git checkout master
+ $ git pull . 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, often this conflict is the
+same conflict you resolved when you created the test merge you
+blew away. `git-rerere` command helps you to resolve this final
+conflicted merge using the information from your earlier hand
+resolve.
+
+Running `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 records the resolved state of these
+files. Suppose you did this when you created the test merge of
+master into the topic branch.
+
+Next time, running `git-rerere` after seeing a conflicted
+automerge, if the conflict is the same as the earlier one
+recorded, it is noticed and a three-way merge between the
+earlier conflicted automerge, the earlier manual resolution, and
+the current conflicted automerge is performed by the command.
+If this three-way merge resolves cleanly, the result is written
+out to your working tree file, so you would 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 update-index` when you are
+satisfied.
+
+As a convenience measure, `git-merge` automatically invokes
+`git-rerere` when it exits with a failed automerge, which
+records it if it is a new conflict, or reuses the earlier hand
+resolve when it is not. `git-commit` also invokes `git-rerere`
+when recording a merge result. What this means is that you do
+not have to do anything special yourself (Note: you still have
+to create `$GIT_DIR/rr-cache` directory to enable this command).
+
+In our example, when you did the test merge, the manual
+resolution is recorded, and it will be reused when you do the
+actual merge later with updated master and topic branch, as long
+as the earlier 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 keep yourself
+up-to-date even before your topic is ready to be sent upstream.
+This would result in falling back to three-way merge, and it
+would conflict the same way the test merge you resolved earlier.
+`git-rerere` is run by `git rebase` to help you resolve this
+conflict.
+
+
+Author
+------
+Written by Junio C Hamano <junkio@cox.net>
+
+GIT
+---
+Part of the gitlink:git[7] suite