Jujutsu Rebase

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jj rebase --onto main vs jj rebase -r @ --onto main¶

Both commands rebase onto main (via --onto/-o), but they differ in which revisions are selected to be rebased.

jj rebase has to be told which revisions to move. When no selector (-b/-s/-r) is given, it defaults to -b @, i.e. it operates on the whole branch containing the working copy @.

1. jj rebase --onto main

   jj rebase --onto main

   With no revision selector, this defaults to -b @, so it rebases the entire branch containing @ onto main. The “branch” is the set of revisions reachable from @ that are not already ancestors of main, plus all their descendants (the revset (main..@)::). Use this when you want to move your current line of work, as a whole, on top of the latest main.

2. jj rebase -r @ --onto main

   jj rebase -r @ --onto main

   With -r @, this rebases only the single revision @ onto main, without its descendants. Any “hole” left behind is filled automatically: @'s original descendants are rebased onto @'s former parent(s), so they stay where they were rather than following @. Use this when you want to lift just one commit out of its current place and replant it on main.

Summary

In short: without a selector, jj rebase moves the whole branch (-b @), whereas -r @ surgically moves just the working-copy revision and leaves its descendants in place.