On Fri, 11 Feb 2022 at 07:57, Christian Gollwitzer <aurio...@gmx.de> wrote:
>
> Am 10.02.22 um 20:43 schrieb Chris Angelico:
> > On Fri, 11 Feb 2022 at 06:41, Dennis Lee Bieber <wlfr...@ix.netcom.com>
> > wrote:
> >> While not tested with Excel, I /have/ encountered cases where an
> >> application has locked the file for writing, but multiple readers are
> >> permitted. Those would fail then if one attempts to write. {The other view
> >> point is a library that does a complete open/read\write-all/close to memory
> >> -- such an application might open/read/close, then Excel opens/locks, with
> >> the application only learning of the change when it attempts the
> >> open/write/close cycle}
> >>
> >
> > Yeah, I doubt Excel is that sophisticated. It's built on an assumption
> > of single-user operation.
> >
>
> It guards against multiple user opening the same file over network
> drives. All MS applications create lock files with weird names like
> ~.original-name.xlsx etc. If you open a file on the network share, and a
> colleague tries to open it from a second machine, then he will get the
> message "File locked by user xy from machine z". See here for word:
> https://support.microsoft.com/en-us/topic/-the-document-is-locked-for-editing-by-another-user-error-message-when-you-try-to-open-a-document-in-word-10b92aeb-2e23-25e0-9110-370af6edb638
>
Yeah, but that's still just hard locking, no "one writer multiple
readers" system or anything.
> I believe (haven't tested) that this is cooperative locking only and it
> doesn't help if you alter the file from another program. On the same
> machine though, I think that Excel opens the file with a flag to lock it
> from other processes. At least that was my observation and also what the
> OP has described.
>
That sounds right; and, again, it's just a simple exclusive lock.
Excel doesn't have the sophistication to need or want anything more
than simple "I have this file, nobody else touch it" exclusive
locking.
ChrisA
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