On Tue, May 16, 2017 at 9:18 AM, Jeff King <peff@xxxxxxxx> wrote: > On Tue, May 16, 2017 at 12:23:02PM +0200, Johannes Schindelin wrote: >> It would appear to me that you used a side effect of an implementation >> detail: that `git rebase -i` was implemented entirely as a shell script. > > I don't think that's true at all. He expected the user-provided "--exec" > command to be run by a shell, which seems like a reasonable thing for > Git to promise (and we already make a similar promise for most > user-provided commands that we run). What happens in between, be it As a "user", my expectation was simply that the command would be run not just in "a shell", but in *my* shell (or the shell that calls git, maybe). So I don't see any portability question with respect to Git. My script that uses git rebase --exec may not be portable, but that's my problem. When I use "git rebase --exec <cmd>" I'm basically writing a "foreach commit in range { <cmd> }" in my shell. Same idea with git bisect run. A transparent optimization that tries execve() then falls back to the user's shell sounds like a good idea.