[TUHS] A few comments on porting the Bourne shell

[Adam Thornton]

> On Jan 2, 2023, at 9:51 AM, Larry McVoy <lm at mcvoy.com> wrote:
> 
> On Mon, Jan 02, 2023 at 11:25:06AM -0500, Clem Cole wrote:
>> Like Larry, I have always been a meany and I have tried to make darned sure
>> my folks (even to this day - we will see how long that last after I retire)
>> use V7 syntax scripts - not bash, not even korn.   
> And as we shipped
> scripts that people expected to work, you can't fix their /bin/sh.
> 
> I won that argument over and over and eventually we all instinctively
> wrote portable scripts.


I feel like after POSIX.2 had had a few years to settle, it was OK to use *that* as your scripting language (I particularly like $() rather than backticks, because of nestability, although you can certainly argue that if you're regularly nesting your interpolations, it's the design that's broken, not the specific syntax of the command).

At least as long as you put a very visible comment right at the top saying "We're assuming POSIX shell."

But of course the "after it had had a few years to settle" is doing a lot of lifting there.  During the Unix Wars, yeah, clearly using v7 sh as lowest-common-denominator was the right choice.  After the establishment of Linux Hegemony sometime in the early 2000s, I think I remember that you could pretty much count on everyone at least providing a POSIX shell, even if it wasn't the default.  (But of course by then, "everyone" that wasn't Linux or OS X was already down to more-or-less Sun, IBM, HP, and DEC/Compaq.)

These days, if you have a vendor-supplied shell script that DOESN'T work correctly under a POSIX /bin/sh, that should be treated as a defect.

Adam