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Re: AW: Bizarre interaction bug involving bash w/ lastpipe + Almquist 'w

From: Martijn Dekker
Subject: Re: AW: Bizarre interaction bug involving bash w/ lastpipe + Almquist 'wait'
Date: Fri, 7 Feb 2020 14:33:46 +0000
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.4.2

Op 07-02-20 om 12:19 schreef Walter Harms:
IMHO is the bug on bash side. ash can assume to get an "healthy"
environment from the caller. You can simply not fix everything that
can possible go wrong.

That is a rather fallacious argument. Of course you cannot fix *everything* that could possibly go wrong. You can certainly fix *this* thing, though. I know, because every non-Almquist shell does it.

These days, no program can realistically assume a "healthy" environment. Computers have become unimaginably complex machines, built on thousands of interdependent abstraction layers, each as fallible as the humans that designed and implemented them. So "unhealthy" environments happen all the time, due to all sorts of unforeseen causes.

It's well past time to accept that the 1980s are behind us. In 2020, systems have to be programmed robustly and defensively.

Obviously it should not segfault but so far i understand it is bsd as
that does, not busybox ash.

True. But instead, it simply gets stuck forever, with no message or other indicator of what went wrong. How is that better?

(Going slightly off-topic below...)

Segfaulting is actually a good thing: it's one form of failing reliably. And failing reliably is vastly better than what often happens instead, especially in shell scripts: subtle breakage, which can take a lot of detective work to trace, and in some cases can cause serious damage due to the program functioning inconsistently and incorrectly (instead of not at all).

Failing reliably is something the shell is ATROCIOUSLY bad at, and it's one of the first things modernish aims to fix.

- Martijn

modernish -- harness the shell

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