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Re: Using Zsh on a embedded system to configure GPIOs
- X-seq: zsh-users 19467
- From: Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>
- To: zsh-users@xxxxxxx
- Subject: Re: Using Zsh on a embedded system to configure GPIOs
- Date: Sat, 29 Nov 2014 11:35:21 -0800
- In-reply-to: <20141129091049.GF4729@solfire>
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- References: <20141129091049.GF4729@solfire>
On Nov 29, 10:10am, meino.cramer@xxxxxx wrote:
} To overwrite files I need to use ">!" instead of ">".
} Is there any way to automate this feature NOT to hit on my fingers,
} if I want to write to files below /sys, /proc,, /dev...or
} (better) to recognize, if such a file is a virtual one?
I confess to being confused by the phrase "to hit on my fingers" ...
but I think I can answer anyway.
The HIST_ALLOW_CLOBBER option replaces ">" with ">|" in the history,
so that if you forget to use the clobbering form all you need to do
is recall the previous command with "!!" or the line editor. Does
NO_CLOBBER already behaves differently for non-regular files, so that
you can do things like "print foo > /dev/pts/3" without having to use
">|" (though that won't work for /dev/tty for a different reason).
So if there is some way to identify a "virtual file" e.g. with stat(),
that could potentially also be handled. However, I think virtual files
masquerade pretty thoroughly as real ones except for the fact that they
appear to have size 0 yet contents can still be read.
I suppose that, since the point of NO_CLOBBER is to prevent destroying
existing file contents, redirection could be allowed to succeed for
existing zero-sized files, which would then work for virtual files.
However, that's not the way it works now, and zsh-workers would need to
have some discussion of whether that change is acceptable.
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