Ok, thanks for the clarification.

On Mon, Aug 22, 2022 at 2:44 PM Bart Schaefer <schaefer@brasslantern.com>
wrote:

> On Mon, Aug 22, 2022 at 1:00 AM Liu Xin <navy.xliu@gmail.com> wrote:
> >
> > I hold the wrong impression that zsh is compatible with bash. I just
> assume it because I see both Ubuntu and MacOS have replaced bash with it.
>
> Zsh is mostly compatible with POSIX shell provided that it is invoked
> via the name "sh" (e.g., when linked to /bin/sh).  Bash is similarly
> compatible with POSIX when run this way.  When run under their own
> names, zsh and bash differ from POSIX in different ways.
>
> Apple and Ubuntu appear to have concluded that zsh's POSIX
> compatibility is sufficient to use it as "sh".  I won't speculate on
> other motivations.
>