Merge branch 'js/rerere-forget-always-take-pathspec'
[git/git.git] / Documentation / git-rerere.txt
1 git-rerere(1)
2 =============
3
4 NAME
5 ----
6 git-rerere - Reuse recorded resolution of conflicted merges
7
8 SYNOPSIS
9 --------
10 'git rerere' ['clear'|'forget' <pathspec>|'diff'|'status'|'gc']
11
12 DESCRIPTION
13 -----------
14
15 In a workflow employing relatively long lived topic branches,
16 the developer sometimes needs to resolve the same conflicts over
17 and over again until the topic branches are done (either merged
18 to the "release" branch, or sent out and accepted upstream).
19
20 This command assists the developer in this process by recording
21 conflicted automerge results and corresponding hand resolve results
22 on the initial manual merge, and applying previously recorded
23 hand resolutions to their corresponding automerge results.
24
25 [NOTE]
26 You need to set the configuration variable rerere.enabled in order to
27 enable this command.
28
29
30 COMMANDS
31 --------
32
33 Normally, 'git rerere' is run without arguments or user-intervention.
34 However, it has several commands that allow it to interact with
35 its working state.
36
37 'clear'::
38
39 This resets the metadata used by rerere if a merge resolution is to be
40 aborted. Calling 'git am [--skip|--abort]' or 'git rebase [--skip|--abort]'
41 will automatically invoke this command.
42
43 'forget' <pathspec>::
44
45 This resets the conflict resolutions which rerere has recorded for the current
46 conflict in <pathspec>.
47
48 'diff'::
49
50 This displays diffs for the current state of the resolution. It is
51 useful for tracking what has changed while the user is resolving
52 conflicts. Additional arguments are passed directly to the system
53 'diff' command installed in PATH.
54
55 'status'::
56
57 Like 'diff', but this only prints the filenames that will be tracked
58 for resolutions.
59
60 'gc'::
61
62 This prunes records of conflicted merges that
63 occurred a long time ago. By default, unresolved conflicts older
64 than 15 days and resolved conflicts older than 60
65 days are pruned. These defaults are controlled via the
66 `gc.rerereunresolved` and `gc.rerereresolved` configuration
67 variables respectively.
68
69
70 DISCUSSION
71 ----------
72
73 When your topic branch modifies an overlapping area that your
74 master branch (or upstream) touched since your topic branch
75 forked from it, you may want to test it with the latest master,
76 even before your topic branch is ready to be pushed upstream:
77
78 ------------
79 o---*---o topic
80 /
81 o---o---o---*---o---o master
82 ------------
83
84 For such a test, you need to merge master and topic somehow.
85 One way to do it is to pull master into the topic branch:
86
87 ------------
88 $ git checkout topic
89 $ git merge master
90
91 o---*---o---+ topic
92 / /
93 o---o---o---*---o---o master
94 ------------
95
96 The commits marked with `*` touch the same area in the same
97 file; you need to resolve the conflicts when creating the commit
98 marked with `{plus}`. Then you can test the result to make sure your
99 work-in-progress still works with what is in the latest master.
100
101 After this test merge, there are two ways to continue your work
102 on the topic. The easiest is to build on top of the test merge
103 commit `{plus}`, and when your work in the topic branch is finally
104 ready, pull the topic branch into master, and/or ask the
105 upstream to pull from you. By that time, however, the master or
106 the upstream might have been advanced since the test merge `{plus}`,
107 in which case the final commit graph would look like this:
108
109 ------------
110 $ git checkout topic
111 $ git merge master
112 $ ... work on both topic and master branches
113 $ git checkout master
114 $ git merge topic
115
116 o---*---o---+---o---o topic
117 / / \
118 o---o---o---*---o---o---o---o---+ master
119 ------------
120
121 When your topic branch is long-lived, however, your topic branch
122 would end up having many such "Merge from master" commits on it,
123 which would unnecessarily clutter the development history.
124 Readers of the Linux kernel mailing list may remember that Linus
125 complained about such too frequent test merges when a subsystem
126 maintainer asked to pull from a branch full of "useless merges".
127
128 As an alternative, to keep the topic branch clean of test
129 merges, you could blow away the test merge, and keep building on
130 top of the tip before the test merge:
131
132 ------------
133 $ git checkout topic
134 $ git merge master
135 $ git reset --hard HEAD^ ;# rewind the test merge
136 $ ... work on both topic and master branches
137 $ git checkout master
138 $ git merge topic
139
140 o---*---o-------o---o topic
141 / \
142 o---o---o---*---o---o---o---o---+ master
143 ------------
144
145 This would leave only one merge commit when your topic branch is
146 finally ready and merged into the master branch. This merge
147 would require you to resolve the conflict, introduced by the
148 commits marked with `*`. However, this conflict is often the
149 same conflict you resolved when you created the test merge you
150 blew away. 'git rerere' helps you resolve this final
151 conflicted merge using the information from your earlier hand
152 resolve.
153
154 Running the 'git rerere' command immediately after a conflicted
155 automerge records the conflicted working tree files, with the
156 usual conflict markers `<<<<<<<`, `=======`, and `>>>>>>>` in
157 them. Later, after you are done resolving the conflicts,
158 running 'git rerere' again will record the resolved state of these
159 files. Suppose you did this when you created the test merge of
160 master into the topic branch.
161
162 Next time, after seeing the same conflicted automerge,
163 running 'git rerere' will perform a three-way merge between the
164 earlier conflicted automerge, the earlier manual resolution, and
165 the current conflicted automerge.
166 If this three-way merge resolves cleanly, the result is written
167 out to your working tree file, so you do not have to manually
168 resolve it. Note that 'git rerere' leaves the index file alone,
169 so you still need to do the final sanity checks with `git diff`
170 (or `git diff -c`) and 'git add' when you are satisfied.
171
172 As a convenience measure, 'git merge' automatically invokes
173 'git rerere' upon exiting with a failed automerge and 'git rerere'
174 records the hand resolve when it is a new conflict, or reuses the earlier hand
175 resolve when it is not. 'git commit' also invokes 'git rerere'
176 when committing a merge result. What this means is that you do
177 not have to do anything special yourself (besides enabling
178 the rerere.enabled config variable).
179
180 In our example, when you do the test merge, the manual
181 resolution is recorded, and it will be reused when you do the
182 actual merge later with the updated master and topic branch, as long
183 as the recorded resolution is still applicable.
184
185 The information 'git rerere' records is also used when running
186 'git rebase'. After blowing away the test merge and continuing
187 development on the topic branch:
188
189 ------------
190 o---*---o-------o---o topic
191 /
192 o---o---o---*---o---o---o---o master
193
194 $ git rebase master topic
195
196 o---*---o-------o---o topic
197 /
198 o---o---o---*---o---o---o---o master
199 ------------
200
201 you could run `git rebase master topic`, to bring yourself
202 up-to-date before your topic is ready to be sent upstream.
203 This would result in falling back to a three-way merge, and it
204 would conflict the same way as the test merge you resolved earlier.
205 'git rerere' will be run by 'git rebase' to help you resolve this
206 conflict.
207
208 GIT
209 ---
210 Part of the linkgit:git[1] suite