Git’s rebase command reapplies your changes onto another branch. As opposed to merging, which pulls the differences from the other branch into yours, rebasing switches your branch’s base to the other branch’s position and walks through your commits one by one to apply them again.
Let’s look at an example. While working on a branch named
login, based on the
main branch, one of your team members pushed some changes to
main. You need these changes to finish the login feature in your branch.
Figure 1: The new commits in the
main branch (
F), are needed to finish work in the
Rebase vs merge
main branch back into yours would result in a merge commit, which includes the changes between both branches and exists to show where a merge occurred.
Merging a branch is useful when the moment of merging is significant. For example, when a feature is merged into the
main branch, or when a new release is pushed.
When working on a branch with multiple people, merging is preferable to rebasing as it leaves the branch history intact.
Figure 2: Merging the two branches results in a merge commit.
In this case, it’s not important to know when
main was merged in, and there is nobody else working on the
login branch. Instead of merging the
main branch in, rebasing it rewrites history to make sure all commits on the
login branch are based on the current state of the
Figure 3: Rebasing applies the commits from the
login branch on top of the
Git’s rebase command temporarily rewinds the commits on your current branch, pulls in the commits from the other branch and reapplies the rewinded commits back on top. This bases the current branch onto the other branch.
$ git rebase main First, rewinding head to replay your work on top of it... Fast-forwarded login to main.
It’s as if you didn’t start working in the
login branch before the commits you pulled in were made1.
Conflicts served in smaller chunks
Unlike a merge, which merges two branches in one go, rebasing applies the changes from one branch one by one. Because of that, conflicts will be served in smaller chunks making them easier to fix and understand:
$ git rebase main First, rewinding head to replay your work on top of it... Applying: login Using index info to reconstruct a base tree... Falling back to patching base and 3-way merge... Auto-merging config/environment.rb CONFLICT (content): Merge conflict in config/environment.rb Failed to merge in the changes. Patch failed at 0001 login When you have resolved this problem run "git rebase --continue". If you would prefer to skip this patch, instead run "git rebase --skip". To restore the original branch and stop rebasing run "git rebase --abort".
When you’re done fixing a conflict, simply
git add the file and continue rebasing:
$ git rebase --continue