bug#61035: [PATCH] cp: improve help regarding ACLs

[Kamil Dudka]

On Sunday, January 29, 2023 11:04:22 PM CET Paul Eggert wrote:
> On 2023-01-29 03:06, Kamil Dudka wrote:
> > On Wednesday, January 25, 2023 11:01:45 PM CET Paul Eggert wrote:
> >> On 2023-01-25 13:56, Ondrej Valousek wrote:
> >>> But it's not the same meaning. What I am trying to explain here is that
> >>>
> >>> Cp -p (or cp --preserve=mode) also retains ACLs. This fact is not 
> >>> obvious, but yet it's happening
> >> Then I'm afraid I don't understand. In what sense do ACLs differ from
> >> xattr here?
> > As I understand it, `cp -p` now preserves ACLs but not xattr (unlike `cp 
> > -a`).
> 
> OK, the light is slowly dawning on me. Though I'm still confused.
> 
> Why are ACLs treated differently from extended attributes? Shouldn't the 
> two be treated the same (assuming they're both supported)?
> 
> In other words, what's the underlying model and motivation here? It's 
> more important to document that, than to document little pieces of it.

I cannot speak for Ondrej.  My understanding is that ACLs can be seen as
extension over permission bits whereas the extended attributes can store
pretty much anything.  I am not saying which approach is (more) correct
though.

Kamil