jj/docs/git-compatibility.md
Martin von Zweigbergk d9b364442e cleanup: update references to .jj/store/git to .jj/repo/store/git
The `store/` directory (and many others) recently moved into
`.jj/repo/`, but I forgot to update a few places.
2022-02-17 22:44:14 -08:00

2.7 KiB

Git compatibility

Jujutsu has two backends for storing commits. One of them uses a regular Git repo, which means that you can collaborate with Git users without them even knowing that you're not using the git CLI.

See jj help git for help about the jj git family of commands, and e.g. jj help git push for help about a specific command (use jj git push --help for more verbose help).

Creating an empty repo

To create an empty repo using the Git backend, use jj init --git <name>. Since the command creates a Jujutsu repo, it will have a .jj/ directory. The underlying Git repo will be inside of that directory (currently in .jj/repo/store/git/).

Creating a repo backed by an existing Git repo

To create a Jujutsu repo backed by a Git repo you already have on disk, use jj init --git-repo=<path to Git repo> <name>. The repo will work similar to a Git worktree, meaning that the working copies and the record of the current checkout will be separate, but the commits will be accessible in both repos. Use jj git import to update the Jujutsu repo with changes made in the Git repo. Use jj git export to update the Git repo with changes made in the Jujutsu repo.

If you create initialize the Jujutsu repo in the same working copy as the Git repo by running jj init --git-repo=., then the import and export will happen automatically on every command (because not doing that makes it very confusing when the current checkout has changed in Git but not in Jujutsu or vice versa). This mode is meant to make it easier to start using readonly jj commands in an existing Git repo. You should then be able to switch to using mutating jj commands and readonly Git commands. The mode is new and not tested much, and interleaving mutating jj and git commands might not work well (feel free to report bugs).

Creating a repo by cloning a Git repo

To create a Jujutsu repo from a remote Git URL, use jj git clone <URL> [<destination>]. For example, jj git clone https://github.com/octocat/Hello-World will clone GitHub's "Hello-World" repo into a directory by the same name.

Branches

TODO: Describe how branches are mapped

Format mapping details

Paths are assumed to be UTF-8. I have no current plans to support paths with other encodings.

Commits created by jj have a ref starting with refs/jj/ to prevent GC.

Commit metadata that cannot be represented in Git commits (such as the Change ID) is stored outside of the Git repo (currently in .jj/store/extra/).

Paths with conflicts cannot be represented in Git. They appear as files with a .jjconflict suffix in the Git repo. They contain a JSON representation with information about the conflict. They are not meant to be human-readable.