Documentation: a few spelling fixes
[git/git.git] / Documentation / git-rerere.txt
1 git-rerere(1)
2 =============
3
4 NAME
5 ----
6 git-rerere - Reuse recorded resolve
7
8 SYNOPSIS
9 --------
10 'git-rerere' [clear|diff|status|gc]
11
12 DESCRIPTION
13 -----------
14
15 In a workflow that employs relatively long lived topic branches,
16 the developer sometimes needs to resolve the same conflict 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 helps this process by recording conflicted
21 automerge results and corresponding hand-resolve results on the
22 initial manual merge, and later by noticing the same automerge
23 results and applying the previously recorded hand resolution.
24
25 [NOTE]
26 You need to create `$GIT_DIR/rr-cache` directory to enable this
27 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 is aborted. Calling gitlink:git-am[1] --skip or gitlink:git-rebase[1]
41 [--skip|--abort] will automatically invoke this command.
42
43 'diff'::
44
45 This displays diffs for the current state of the resolution. It is
46 useful for tracking what has changed while the user is resolving
47 conflicts. Additional arguments are passed directly to the system
48 diff(1) command installed in PATH.
49
50 'status'::
51
52 Like diff, but this only prints the filenames that will be tracked
53 for resolutions.
54
55 'gc'::
56
57 This command is used to prune records of conflicted merge that
58 occurred long time ago. By default, conflicts older than 15
59 days that you have not recorded their resolution, and conflicts
60 older than 60 days, are pruned. These are controlled with
61 `gc.rerereunresolved` and `gc.rerereresolved` configuration
62 variables.
63
64
65 DISCUSSION
66 ----------
67
68 When your topic branch modifies overlapping area that your
69 master branch (or upstream) touched since your topic branch
70 forked from it, you may want to test it with the latest master,
71 even before your topic branch is ready to be pushed upstream:
72
73 ------------
74 o---*---o topic
75 /
76 o---o---o---*---o---o master
77 ------------
78
79 For such a test, you need to merge master and topic somehow.
80 One way to do it is to pull master into the topic branch:
81
82 ------------
83 $ git checkout topic
84 $ git merge master
85
86 o---*---o---+ topic
87 / /
88 o---o---o---*---o---o master
89 ------------
90
91 The commits marked with `*` touch the same area in the same
92 file; you need to resolve the conflicts when creating the commit
93 marked with `+`. Then you can test the result to make sure your
94 work-in-progress still works with what is in the latest master.
95
96 After this test merge, there are two ways to continue your work
97 on the topic. The easiest is to build on top of the test merge
98 commit `+`, and when your work in the topic branch is finally
99 ready, pull the topic branch into master, and/or ask the
100 upstream to pull from you. By that time, however, the master or
101 the upstream might have been advanced since the test merge `+`,
102 in which case the final commit graph would look like this:
103
104 ------------
105 $ git checkout topic
106 $ git merge master
107 $ ... work on both topic and master branches
108 $ git checkout master
109 $ git merge topic
110
111 o---*---o---+---o---o topic
112 / / \
113 o---o---o---*---o---o---o---o---+ master
114 ------------
115
116 When your topic branch is long-lived, however, your topic branch
117 would end up having many such "Merge from master" commits on it,
118 which would unnecessarily clutter the development history.
119 Readers of the Linux kernel mailing list may remember that Linus
120 complained about such too frequent test merges when a subsystem
121 maintainer asked to pull from a branch full of "useless merges".
122
123 As an alternative, to keep the topic branch clean of test
124 merges, you could blow away the test merge, and keep building on
125 top of the tip before the test merge:
126
127 ------------
128 $ git checkout topic
129 $ git merge master
130 $ git reset --hard HEAD^ ;# rewind the test merge
131 $ ... work on both topic and master branches
132 $ git checkout master
133 $ git merge topic
134
135 o---*---o-------o---o topic
136 / \
137 o---o---o---*---o---o---o---o---+ master
138 ------------
139
140 This would leave only one merge commit when your topic branch is
141 finally ready and merged into the master branch. This merge
142 would require you to resolve the conflict, introduced by the
143 commits marked with `*`. However, often this conflict is the
144 same conflict you resolved when you created the test merge you
145 blew away. `git-rerere` command helps you to resolve this final
146 conflicted merge using the information from your earlier hand
147 resolve.
148
149 Running `git-rerere` command immediately after a conflicted
150 automerge records the conflicted working tree files, with the
151 usual conflict markers `<<<<<<<`, `=======`, and `>>>>>>>` in
152 them. Later, after you are done resolving the conflicts,
153 running `git-rerere` again records the resolved state of these
154 files. Suppose you did this when you created the test merge of
155 master into the topic branch.
156
157 Next time, running `git-rerere` after seeing a conflicted
158 automerge, if the conflict is the same as the earlier one
159 recorded, it is noticed and a three-way merge between the
160 earlier conflicted automerge, the earlier manual resolution, and
161 the current conflicted automerge is performed by the command.
162 If this three-way merge resolves cleanly, the result is written
163 out to your working tree file, so you would not have to manually
164 resolve it. Note that `git-rerere` leaves the index file alone,
165 so you still need to do the final sanity checks with `git diff`
166 (or `git diff -c`) and `git update-index` when you are
167 satisfied.
168
169 As a convenience measure, `git-merge` automatically invokes
170 `git-rerere` when it exits with a failed automerge, which
171 records it if it is a new conflict, or reuses the earlier hand
172 resolve when it is not. `git-commit` also invokes `git-rerere`
173 when recording a merge result. What this means is that you do
174 not have to do anything special yourself (Note: you still have
175 to create `$GIT_DIR/rr-cache` directory to enable this command).
176
177 In our example, when you did the test merge, the manual
178 resolution is recorded, and it will be reused when you do the
179 actual merge later with updated master and topic branch, as long
180 as the earlier resolution is still applicable.
181
182 The information `git-rerere` records is also used when running
183 `git-rebase`. After blowing away the test merge and continuing
184 development on the topic branch:
185
186 ------------
187 o---*---o-------o---o topic
188 /
189 o---o---o---*---o---o---o---o master
190
191 $ git rebase master topic
192
193 o---*---o-------o---o topic
194 /
195 o---o---o---*---o---o---o---o master
196 ------------
197
198 you could run `git rebase master topic`, to keep yourself
199 up-to-date even before your topic is ready to be sent upstream.
200 This would result in falling back to three-way merge, and it
201 would conflict the same way the test merge you resolved earlier.
202 `git-rerere` is run by `git rebase` to help you resolve this
203 conflict.
204
205
206 Author
207 ------
208 Written by Junio C Hamano <junkio@cox.net>
209
210 GIT
211 ---
212 Part of the gitlink:git[7] suite