Stephane CHAZELAS wrote:
>
> Some shells like zsh and some versions of ksh have an

I think that _all_ ksh's (88 and 93) would behave the way you
describe below. Or did you count that PD thing also as "ksh"?
(Which I would find more confusing than ful, specifically
because of that fundamental difference.)

> optimisation in that the right-most command in a pipeline, if
> builtin, is run by the current shell process. Most other shells
> (ash, pdksh, bash) run every command in child processes of the
> current shell.

What about the Bourne shell's behaviour? (I've none available
to check.)

Janis