1GIT-RERERE(1) Git Manual GIT-RERERE(1)
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6 git-rerere - Reuse recorded resolution of conflicted merges
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9 git rerere [clear|forget <pathspec>|diff|remaining|status|gc]
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12 In a workflow employing relatively long lived topic branches, the
13 developer sometimes needs to resolve the same conflicts over and over
14 again until the topic branches are done (either merged to the "release"
15 branch, or sent out and accepted upstream).
16 This command assists the developer in this process by recording
18 conflicted automerge results and corresponding hand resolve results on
19 the initial manual merge, and applying previously recorded hand
20 resolutions to their corresponding automerge results.
21 Note
23 You need to set the configuration variable rerere.enabled in order
24 to enable this command.
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27 Normally, git rerere is run without arguments or user-intervention.
28 However, it has several commands that allow it to interact with its
29 working state.
30 clear
32 Reset the metadata used by rerere if a merge resolution is to be
33 aborted. Calling git am [--skip|--abort] or git rebase
34 [--skip|--abort] will automatically invoke this command.
35 forget <pathspec>
37 Reset the conflict resolutions which rerere has recorded for the
38 current conflict in <pathspec>.
39 diff
41 Display diffs for the current state of the resolution. It is useful
42 for tracking what has changed while the user is resolving
43 conflicts. Additional arguments are passed directly to the system
44 diff command installed in PATH.
45 status
47 Print paths with conflicts whose merge resolution rerere will
48 record.
49 remaining
51 Print paths with conflicts that have not been autoresolved by
52 rerere. This includes paths whose resolutions cannot be tracked by
53 rerere, such as conflicting submodules.
54 gc
56 Prune records of conflicted merges that occurred a long time ago.
57 By default, unresolved conflicts older than 15 days and resolved
58 conflicts older than 60 days are pruned. These defaults are
59 controlled via the gc.rerereUnresolved and gc.rerereResolved
60 configuration variables respectively.
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63 When your topic branch modifies an overlapping area that your master
64 branch (or upstream) touched since your topic branch forked from it,
65 you may want to test it with the latest master, even before your topic
66 branch is ready to be pushed upstream:
67 o---*---o topic
69 /
70 o---o---o---*---o---o master
71 For such a test, you need to merge master and topic somehow. One way to
73 do it is to pull master into the topic branch:
74 $ git switch topic
76 $ git merge master
77 o---*---o---+ topic
79 / /
80 o---o---o---*---o---o master
81 The commits marked with * touch the same area in the same file; you
83 need to resolve the conflicts when creating the commit marked with +.
84 Then you can test the result to make sure your work-in-progress still
85 works with what is in the latest master.
86 After this test merge, there are two ways to continue your work on the
88 topic. The easiest is to build on top of the test merge commit +, and
89 when your work in the topic branch is finally ready, pull the topic
90 branch into master, and/or ask the upstream to pull from you. By that
91 time, however, the master or the upstream might have been advanced
92 since the test merge +, in which case the final commit graph would look
93 like this:
94 $ git switch topic
96 $ git merge master
97 $ ... work on both topic and master branches
98 $ git switch master
99 $ git merge topic
100 o---*---o---+---o---o topic
102 / / \
103 o---o---o---*---o---o---o---o---+ master
104 When your topic branch is long-lived, however, your topic branch would
106 end up having many such "Merge from master" commits on it, which would
107 unnecessarily clutter the development history. Readers of the Linux
108 kernel mailing list may remember that Linus complained about such too
109 frequent test merges when a subsystem maintainer asked to pull from a
110 branch full of "useless merges".
111 As an alternative, to keep the topic branch clean of test merges, you
113 could blow away the test merge, and keep building on top of the tip
114 before the test merge:
115 $ git switch topic
117 $ git merge master
118 $ git reset --hard HEAD^ ;# rewind the test merge
119 $ ... work on both topic and master branches
120 $ git switch master
121 $ git merge topic
122 o---*---o-------o---o topic
124 / \
125 o---o---o---*---o---o---o---o---+ master
126 This would leave only one merge commit when your topic branch is
128 finally ready and merged into the master branch. This merge would
129 require you to resolve the conflict, introduced by the commits marked
130 with *. However, this conflict is often the same conflict you resolved
131 when you created the test merge you blew away. git rerere helps you
132 resolve this final conflicted merge using the information from your
133 earlier hand resolve.
134 Running the git rerere command immediately after a conflicted automerge
136 records the conflicted working tree files, with the usual conflict
137 markers <<<<<<<, =======, and >>>>>>> in them. Later, after you are
138 done resolving the conflicts, running git rerere again will record the
139 resolved state of these files. Suppose you did this when you created
140 the test merge of master into the topic branch.
141 Next time, after seeing the same conflicted automerge, running git
143 rerere will perform a three-way merge between the earlier conflicted
144 automerge, the earlier manual resolution, and the current conflicted
145 automerge. If this three-way merge resolves cleanly, the result is
146 written out to your working tree file, so you do not have to manually
147 resolve it. Note that git rerere leaves the index file alone, so you
148 still need to do the final sanity checks with git diff (or git diff -c)
149 and git add when you are satisfied.
150 As a convenience measure, git merge automatically invokes git rerere
152 upon exiting with a failed automerge and git rerere records the hand
153 resolve when it is a new conflict, or reuses the earlier hand resolve
154 when it is not. git commit also invokes git rerere when committing a
155 merge result. What this means is that you do not have to do anything
156 special yourself (besides enabling the rerere.enabled config variable).
157 In our example, when you do the test merge, the manual resolution is
159 recorded, and it will be reused when you do the actual merge later with
160 the updated master and topic branch, as long as the recorded resolution
161 is still applicable.
162 The information git rerere records is also used when running git
164 rebase. After blowing away the test merge and continuing development on
165 the topic branch:
166 o---*---o-------o---o topic
168 /
169 o---o---o---*---o---o---o---o master
170 $ git rebase master topic
172 o---*---o-------o---o topic
174 /
175 o---o---o---*---o---o---o---o master
176 you could run git rebase master topic, to bring yourself up to date
178 before your topic is ready to be sent upstream. This would result in
179 falling back to a three-way merge, and it would conflict the same way
180 as the test merge you resolved earlier. git rerere will be run by git
181 rebase to help you resolve this conflict.
182 [NOTE] git rerere relies on the conflict markers in the file to detect
184 the conflict. If the file already contains lines that look the same as
185 lines with conflict markers, git rerere may fail to record a conflict
186 resolution. To work around this, the conflict-marker-size setting in
187 gitattributes(5) can be used.
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190 Part of the git(1) suite
191Git 2.33.1 2021-10-12 GIT-RERERE(1)