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Re: Any way to allow clobbering empty files when noclobber is set?
- X-seq: zsh-workers 46010
- From: Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>
- To: zsh-workers@xxxxxxx
- Subject: Re: Any way to allow clobbering empty files when noclobber is set?
- Date: Sat, 06 Jun 2020 17:24:14 +0100
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On Sat, 2020-06-06 at 08:24 -0700, Bart Schaefer wrote:
> Just to clarify: O_CREAT|O_EXCL is actually the NO_clobber-ing open.
> The clobbering open is just to open it for writing if allowed to. and
> start scribbling over whatever is there.
You're right; in the hypothesised case, the file already exists and
this pair of options is documented to fail in that case.
I think the O_TRUNC is therefore the crucial one in our normal clobbering
/* If clobbering, just open. */
if (isset(CLOBBER) || IS_CLOBBER_REDIR(f->type))
O_WRONLY | O_CREAT | O_TRUNC | O_NOCTTY, 0666);
We'll truncate at that point, then start writing. That's the best
we can do. If anyone else is also writing to at *at that point*
--- out of luck, only file locking will help.
> Consequently we should be looking at this as an entirely interactive
> user DWIM feature, and choosing how to implement (or not to) based on
Yes, I certainly agree with that.
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