1git-rerere(1) 2============= 3 4NAME 5---- 6git-rerere - Reuse recorded resolution of conflicted merges 7 8SYNOPSIS 9-------- 10'git-rerere' [clear|diff|status|gc] 11 12DESCRIPTION 13----------- 14 15In a workflow that employs relatively long lived topic branches, 16the developer sometimes needs to resolve the same conflict over 17and over again until the topic branches are done (either merged 18to the "release" branch, or sent out and accepted upstream). 19 20This command helps this process by recording conflicted 21automerge results and corresponding hand-resolve results on the 22initial manual merge, and later by noticing the same automerge 23results and applying the previously recorded hand resolution. 24 25[NOTE] 26You need to set the configuration variable rerere.enabled to 27enable this command. 28 29 30COMMANDS 31-------- 32 33Normally, git-rerere is run without arguments or user-intervention. 34However, it has several commands that allow it to interact with 35its working state. 36 37'clear':: 38 39This resets the metadata used by rerere if a merge resolution is to be 40is aborted. Calling linkgit:git-am[1] --skip or linkgit:git-rebase[1] 41[--skip|--abort] will automatically invoke this command. 42 43'diff':: 44 45This displays diffs for the current state of the resolution. It is 46useful for tracking what has changed while the user is resolving 47conflicts. Additional arguments are passed directly to the system 48diff(1) command installed in PATH. 49 50'status':: 51 52Like diff, but this only prints the filenames that will be tracked 53for resolutions. 54 55'gc':: 56 57This command is used to prune records of conflicted merge that 58occurred long time ago. By default, conflicts older than 15 59days that you have not recorded their resolution, and conflicts 60older than 60 days, are pruned. These are controlled with 61`gc.rerereunresolved` and `gc.rerereresolved` configuration 62variables. 63 64 65DISCUSSION 66---------- 67 68When your topic branch modifies overlapping area that your 69master branch (or upstream) touched since your topic branch 70forked from it, you may want to test it with the latest master, 71even 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 79For such a test, you need to merge master and topic somehow. 80One 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 91The commits marked with `*` touch the same area in the same 92file; you need to resolve the conflicts when creating the commit 93marked with `+`. Then you can test the result to make sure your 94work-in-progress still works with what is in the latest master. 95 96After this test merge, there are two ways to continue your work 97on the topic. The easiest is to build on top of the test merge 98commit `+`, and when your work in the topic branch is finally 99ready, pull the topic branch into master, and/or ask the 100upstream to pull from you. By that time, however, the master or 101the upstream might have been advanced since the test merge `+`, 102in 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 116When your topic branch is long-lived, however, your topic branch 117would end up having many such "Merge from master" commits on it, 118which would unnecessarily clutter the development history. 119Readers of the Linux kernel mailing list may remember that Linus 120complained about such too frequent test merges when a subsystem 121maintainer asked to pull from a branch full of "useless merges". 122 123As an alternative, to keep the topic branch clean of test 124merges, you could blow away the test merge, and keep building on 125top 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 140This would leave only one merge commit when your topic branch is 141finally ready and merged into the master branch. This merge 142would require you to resolve the conflict, introduced by the 143commits marked with `*`. However, often this conflict is the 144same conflict you resolved when you created the test merge you 145blew away. `git-rerere` command helps you to resolve this final 146conflicted merge using the information from your earlier hand 147resolve. 148 149Running `git-rerere` command immediately after a conflicted 150automerge records the conflicted working tree files, with the 151usual conflict markers `<<<<<<<`, `=======`, and `>>>>>>>` in 152them. Later, after you are done resolving the conflicts, 153running `git-rerere` again records the resolved state of these 154files. Suppose you did this when you created the test merge of 155master into the topic branch. 156 157Next time, running `git-rerere` after seeing a conflicted 158automerge, if the conflict is the same as the earlier one 159recorded, it is noticed and a three-way merge between the 160earlier conflicted automerge, the earlier manual resolution, and 161the current conflicted automerge is performed by the command. 162If this three-way merge resolves cleanly, the result is written 163out to your working tree file, so you would not have to manually 164resolve it. Note that `git-rerere` leaves the index file alone, 165so you still need to do the final sanity checks with `git diff` 166(or `git diff -c`) and `git add` when you are satisfied. 167 168As a convenience measure, `git-merge` automatically invokes 169`git-rerere` when it exits with a failed automerge, which 170records it if it is a new conflict, or reuses the earlier hand 171resolve when it is not. `git-commit` also invokes `git-rerere` 172when recording a merge result. What this means is that you do 173not have to do anything special yourself (Note: you still have 174to set the config variable rerere.enabled to enable this command). 175 176In our example, when you did the test merge, the manual 177resolution is recorded, and it will be reused when you do the 178actual merge later with updated master and topic branch, as long 179as the earlier resolution is still applicable. 180 181The information `git-rerere` records is also used when running 182`git-rebase`. After blowing away the test merge and continuing 183development on the topic branch: 184 185------------ 186 o---*---o-------o---o topic 187 / 188 o---o---o---*---o---o---o---o master 189 190 $ git rebase master topic 191 192 o---*---o-------o---o topic 193 / 194 o---o---o---*---o---o---o---o master 195------------ 196 197you could run `git rebase master topic`, to keep yourself 198up-to-date even before your topic is ready to be sent upstream. 199This would result in falling back to three-way merge, and it 200would conflict the same way the test merge you resolved earlier. 201`git-rerere` is run by `git rebase` to help you resolve this 202conflict. 203 204 205Author 206------ 207Written by Junio C Hamano <junkio@cox.net> 208 209GIT 210--- 211Part of the linkgit:git[1] suite