Is there some kind of 'git rebase --dry-run', which would notify me of conflicts in advance?

Question

I'm trying to script rebasing and my script will take different paths depending on if the rebase results in any conflicts.

Is there a way to determine if a rebase would result in conflicts before executing the rebase?

Answer 1

At the time of writing (Git v2.6.1 v2.10.0), the git rebase command offers no --dry-run option. There is no way of knowing, before actually attempting a rebase, whether or not you're going to run into conflicts.

However, if you run git rebase and hit a conflict, the process will stop and exit with a nonzero status. What you could do is check the exit status of the rebase operation, and, if it is nonzero, run git rebase --abort to cancel the rebase:

git rebase ... || git rebase --abort 

And what if the rebase is successful but you realise that you want to undo it, you can run

git reset --hard ORIG_HEAD 

Answer 2

If you just want to see if the rebase would be successful but then you want to "roll back," you can alway reposition the branch tip back to the original commit. Just tag or make a note of the original SHA.

Or perhaps easier, create a new temporary branch in which to "stage" the rebase:

git checkout your-branch git checkout -b tmp git rebase other-branch 

If it was successful but you want to "roll back," your-branch is untouched. Just git branch -D tmp and you're back to where you started from.

If there were conflicts and you did some work to resolve them and you now you want to keep the rebase, just reposition your-branch tip to tmp (and then git branch -D tmp).