I recommend reading the git-rev-parse(1) man page in full, it’ll give you good ideas for this sort of thing. What you’re looking for could be spelled $(git mer

I recommend reading the git-rev-parse(1) man page in full, it’ll give you good ideas for this sort of thing. What you’re looking for could be spelled $(git merge-base HEAD master) (that’s a subshell invocation, outputting a single commit ID). In some circumstances dotted range notation might do: master.. includes all the commits after master and HEAD diverge. That’s good for logging, for example, but not so useful for the sort of rebasing you’re describing, where you may wish to use the merge base instead.