[TUHS] A few comments on porting the Bourne shell

[John Cowan]

On Mon, Jan 2, 2023 at 12:43 PM Larry McVoy <lm at mcvoy.com> wrote:


> I was supporting a commercial product in the early 2000's and there
> were all sorts of systems then that had old shells.  Yes, you could make
> everything a 2 level thing where the first level finds the correct shell,
> but that's just fuss.  Just make things portable, it's not that hard
> and it works everywhere.
>

Making shell scripts portable means not using pipelines, because given "foo
| bar", kshNN and zsh execute foo in a subshell and bar in the top-level
shell, whereas in other shells, both foo and bar execute in subshells.
(For this reason, Posix allows either behavior.)  Not having pipelines is a
pretty drastic limitation.
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