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diff --git a/doc/sync.mdwn b/doc/sync.mdwn new file mode 100644 index 000000000..37b2b1b45 --- /dev/null +++ b/doc/sync.mdwn @@ -0,0 +1,38 @@ +The `git annex sync` command provides an easy way to keep several +repositories in sync. + +Often git is used in a centralized fashion with a central bare repository +which changes are pulled and pushed to using normal git commands. +That works fine, if you don't mind having a central repository. + +But it can be harder to use git in a fully decentralized fashion, with no +central repository and still keep repositories in sync with one another. +You have to remember to pull from each remote, and merge the appropriate +branch after pulling. It's difficult to *push* to a remote, since git does +not allow pushes into the currently checked out branch. + +`git annex sync` makes it easier using a scheme devised by Joachim +Breitner. The idea is to have a branch `synced/master` (actually, +`synced/$currentbranch`), that is never directly checked out, and serves +as a drop-point for other repositories to use to push changes. + +When you run `git annex sync`, it merges the `synced/master` branch +into `master`, receiving anything that's been pushed to it. (If there is a +conflict in this merge, [[automatic_conflict_resolution]] is used to +resolve it). Then it fetches from each remote, and merges in any changes that +have been made to the remotes too. Finally, it updates `synced/master` +to reflect the new state of `master`, and pushes it out to each of the remotes. + +This way, changes propagate around between repositories as `git annex sync` +is run on each of them. Every repository does not need to be able to talk +to every other repository; as long as the graph of repositories is +connected, and `git annex sync` is run from time to time on each, a given +change, made anywhere, will eventually reach every other repository. + +The workflow for using `git annex sync` is simple: + +* Make some changes to files in the repository, using `git-annex`, + or anything else. +* Run `git annex sync` to save the changes. +* Next time you're working on a different clone of that repository, + run `git annex sync` to update it. |