[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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