1git-rerere(1) 2============= 3 4NAME 5---- 6git-rerere - Reuse recorded resolution of conflicted merges 7 8SYNOPSIS 9-------- 10[verse] 11'git rerere' ['clear'|'forget' <pathspec>|'diff'|'remaining'|'status'|'gc'] 12 13DESCRIPTION 14----------- 15 16In a workflow employing relatively long lived topic branches, 17the developer sometimes needs to resolve the same conflicts over 18and over again until the topic branches are done (either merged 19to the "release" branch, or sent out and accepted upstream). 20 21This command assists the developer in this process by recording 22conflicted automerge results and corresponding hand resolve results 23on the initial manual merge, and applying previously recorded 24hand resolutions to their corresponding automerge results. 25 26[NOTE] 27You need to set the configuration variable rerere.enabled in order to 28enable this command. 29 30 31COMMANDS 32-------- 33 34Normally, 'git rerere' is run without arguments or user-intervention. 35However, it has several commands that allow it to interact with 36its working state. 37 38'clear':: 39 40Reset the metadata used by rerere if a merge resolution is to be 41aborted. Calling 'git am [--skip|--abort]' or 'git rebase [--skip|--abort]' 42will automatically invoke this command. 43 44'forget' <pathspec>:: 45 46Reset the conflict resolutions which rerere has recorded for the current 47conflict in <pathspec>. 48 49'diff':: 50 51Display diffs for the current state of the resolution. It is 52useful for tracking what has changed while the user is resolving 53conflicts. Additional arguments are passed directly to the system 54'diff' command installed in PATH. 55 56'status':: 57 58Print paths with conflicts whose merge resolution rerere will record. 59 60'remaining':: 61 62Print paths with conflicts that have not been autoresolved by rerere. 63This includes paths whose resolutions cannot be tracked by rerere, 64such as conflicting submodules. 65 66'gc':: 67 68Prune records of conflicted merges that 69occurred a long time ago. By default, unresolved conflicts older 70than 15 days and resolved conflicts older than 60 71days are pruned. These defaults are controlled via the 72`gc.rerereUnresolved` and `gc.rerereResolved` configuration 73variables respectively. 74 75 76DISCUSSION 77---------- 78 79When your topic branch modifies an overlapping area that your 80master branch (or upstream) touched since your topic branch 81forked from it, you may want to test it with the latest master, 82even before your topic branch is ready to be pushed upstream: 83 84------------ 85 o---*---o topic 86 / 87 o---o---o---*---o---o master 88------------ 89 90For such a test, you need to merge master and topic somehow. 91One way to do it is to pull master into the topic branch: 92 93------------ 94 $ git checkout topic 95 $ git merge master 96 97 o---*---o---+ topic 98 / / 99 o---o---o---*---o---o master 100------------ 101 102The commits marked with `*` touch the same area in the same 103file; you need to resolve the conflicts when creating the commit 104marked with `+`. Then you can test the result to make sure your 105work-in-progress still works with what is in the latest master. 106 107After this test merge, there are two ways to continue your work 108on the topic. The easiest is to build on top of the test merge 109commit `+`, and when your work in the topic branch is finally 110ready, pull the topic branch into master, and/or ask the 111upstream to pull from you. By that time, however, the master or 112the upstream might have been advanced since the test merge `+`, 113in which case the final commit graph would look like this: 114 115------------ 116 $ git checkout topic 117 $ git merge master 118 $ ... work on both topic and master branches 119 $ git checkout master 120 $ git merge topic 121 122 o---*---o---+---o---o topic 123 / / \ 124 o---o---o---*---o---o---o---o---+ master 125------------ 126 127When your topic branch is long-lived, however, your topic branch 128would end up having many such "Merge from master" commits on it, 129which would unnecessarily clutter the development history. 130Readers of the Linux kernel mailing list may remember that Linus 131complained about such too frequent test merges when a subsystem 132maintainer asked to pull from a branch full of "useless merges". 133 134As an alternative, to keep the topic branch clean of test 135merges, you could blow away the test merge, and keep building on 136top of the tip before the test merge: 137 138------------ 139 $ git checkout topic 140 $ git merge master 141 $ git reset --hard HEAD^ ;# rewind the test merge 142 $ ... work on both topic and master branches 143 $ git checkout master 144 $ git merge topic 145 146 o---*---o-------o---o topic 147 / \ 148 o---o---o---*---o---o---o---o---+ master 149------------ 150 151This would leave only one merge commit when your topic branch is 152finally ready and merged into the master branch. This merge 153would require you to resolve the conflict, introduced by the 154commits marked with `*`. However, this conflict is often the 155same conflict you resolved when you created the test merge you 156blew away. 'git rerere' helps you resolve this final 157conflicted merge using the information from your earlier hand 158resolve. 159 160Running the 'git rerere' command immediately after a conflicted 161automerge records the conflicted working tree files, with the 162usual conflict markers `<<<<<<<`, `=======`, and `>>>>>>>` in 163them. Later, after you are done resolving the conflicts, 164running 'git rerere' again will record the resolved state of these 165files. Suppose you did this when you created the test merge of 166master into the topic branch. 167 168Next time, after seeing the same conflicted automerge, 169running 'git rerere' will perform a three-way merge between the 170earlier conflicted automerge, the earlier manual resolution, and 171the current conflicted automerge. 172If this three-way merge resolves cleanly, the result is written 173out to your working tree file, so you do not have to manually 174resolve it. Note that 'git rerere' leaves the index file alone, 175so you still need to do the final sanity checks with `git diff` 176(or `git diff -c`) and 'git add' when you are satisfied. 177 178As a convenience measure, 'git merge' automatically invokes 179'git rerere' upon exiting with a failed automerge and 'git rerere' 180records the hand resolve when it is a new conflict, or reuses the earlier hand 181resolve when it is not. 'git commit' also invokes 'git rerere' 182when committing a merge result. What this means is that you do 183not have to do anything special yourself (besides enabling 184the rerere.enabled config variable). 185 186In our example, when you do the test merge, the manual 187resolution is recorded, and it will be reused when you do the 188actual merge later with the updated master and topic branch, as long 189as the recorded resolution is still applicable. 190 191The information 'git rerere' records is also used when running 192'git rebase'. After blowing away the test merge and continuing 193development on the topic branch: 194 195------------ 196 o---*---o-------o---o topic 197 / 198 o---o---o---*---o---o---o---o master 199 200 $ git rebase master topic 201 202 o---*---o-------o---o topic 203 / 204 o---o---o---*---o---o---o---o master 205------------ 206 207you could run `git rebase master topic`, to bring yourself 208up-to-date before your topic is ready to be sent upstream. 209This would result in falling back to a three-way merge, and it 210would conflict the same way as the test merge you resolved earlier. 211'git rerere' will be run by 'git rebase' to help you resolve this 212conflict. 213 214GIT 215--- 216Part of the linkgit:git[1] suite