[TUHS] Macs and future unix derivatives
Chet Ramey
chet.ramey at case.edu
Wed Feb 10 05:06:25 AEST 2021
On 2/9/21 12:31 PM, John Cowan wrote:
> From BTSJ 57:6:
>
> The file system maintains no locks visible to the user, nor is there
> any restriction on the number of users who may have a file open for
> reading or writing. Although it is possible for the contents of a file
> to become scrambled when two users write on it simultaneously, in
> practice difficulties do not arise.We take the view that locks are
> neither necessary nor sufficient, in our environment, to prevent
> interference between users of the same file. They are unnecessary
> because we are not faced with large, single-file databases maintained
> by independent processes. They are insufficient because locks in the
> ordinary sense, whereby one user is prevented from writing on a file
> that another user is reading, cannot prevent confusion when, for
> example, both users are editing a file with an editor that makes a copy
> of the file being edited.
"In our environment" is doing some pretty heavy lifting there.
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU chet at case.edu http://tiswww.cwru.edu/~chet/
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