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Re: AW: Bizarre interaction bug involving bash w/ lastpipe + Almquist 'w
Re: AW: Bizarre interaction bug involving bash w/ lastpipe + Almquist 'wait'
Fri, 7 Feb 2020 14:33:46 +0000
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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.
modernish -- harness the shell