From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: Bart Schaefer <schaefer@brasslantern.com>, zsh-workers@zsh.org
Cc: tvboyd23@gmail.com
Subject: Re: Documentation about Multios is misleading, and perhaps untrue
Date: Thu, 11 Oct 2018 20:35:19 +0000 [thread overview]
Message-ID: <1539290119.4188692.1539037288.272C51E2@webmail.messagingengine.com> (raw)
In-Reply-To: <CAH+w=7ZMCr9qDUM9MBXKf4C8nu=HV4TTVOQdsB-gb=oJGDVB4g@mail.gmail.com>
Bart Schaefer wrote on Thu, 11 Oct 2018 12:12 -0700:
> On Wed, Oct 10, 2018 at 9:05 PM dana <dana@dana.is> wrote:
> >
> > On 10 Oct 2018, at 21:33, Tom Boyd <tvboyd23@gmail.com> wrote:
> > >What should be done about this ?
> >
> > Not sure if there's really an issue with the rest
>
> A bit of common sense has to be applied here. These are redirection
> operators and are going to behave first like redirection operators,
> which means that the shell is going to open the file descriptors
> before executing any of the commands, and then pass those descriptors
> around. The semantics of redirections demands this. An external
> command like "cat" receives a list of names in its argument list and
> processes the names one by one, so it can completely open and close
> the file with each name before moving on to the next one, but the
> shell can't do that and would be broken in other cases if it tried.
>
> It's pointless to try to call call out every possible instance where
> the fundamental semantics of shell operations affect a particular use
> of the syntax.
I won't disagree with such a broad statement, but on the other hand, I
don't think "We shouldn't document this because this is how the OS
limitations force us to implement the shell" is a useful stance, either.
Readers of zshall(1) should not be assumed to be familiar with the C
syscalls and library interfaces' limitations.
next prev parent reply other threads:[~2018-10-11 20:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 2:33 Tom Boyd
2018-10-11 4:05 ` dana
2018-10-11 19:12 ` Bart Schaefer
2018-10-11 20:35 ` Daniel Shahaf [this message]
2018-10-11 20:59 ` Bart Schaefer
2018-10-12 8:30 ` Peter Stephenson
2018-10-16 0:45 ` Tom Boyd
2018-10-16 2:07 ` Daniel Shahaf
2018-10-16 9:33 ` Peter Stephenson
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