[OpenAFS] user-visible change suggestion for fs setacl

[Simon Wilkinson]

On 16 Dec 2008, at 18:42, Derrick J Brashear wrote:

> The provided patch adds the ability to add or subtract rights from  
> an acl element, e.g. a+ or a- to add or subtract the administer bit  
> from an acl, like fs sa . shadow a+
> would give shadow the a bit in addition to whatever bits he already  
> had.
>
> It's user-visible. Before we go anywhere with it, ignoring code  
> issues, what UI should this have, assuming we do want this feature  
> (I certianly see the utility)

I can also see the usefulness of this function - so that's a +1 for  
the idea!

With regards to the UI, I think the obvious parallel is with the Unix  
chmod command. Interestingly, that has the opposite in terms of  
modifier position - chmod has u +x, or u -x, rather than u x- as you  
suggest here. I wonder if that might be a more obvious syntax?

It would also be good to clarify to what extent compound expressions  
(a+l-r+, for example) will be supported.

Cheers,

Simon.