Copying EAs and ACLs

Axel Thimm Axel.Thimm at
Mon Mar 10 04:45:18 EST 2003

On Sun, Mar 02, 2003 at 04:50:23AM -0800, jw schultz wrote:
> Access Control Lists (ACLs) and Extended Attributes (EA) are
> an area i have seen for some time as something rsync will
> need to address.  I've put a tighter focus on this issue for
> the past week or so and have reached a few conclusions.
> 1. ACL and EA OS support is growing but not really there yet.
> 2. Utility support is almost completely missing.
> 3. Use lags support dramatically.
> 4. ACLs and EAs are a part of the future.
> 	Users and admins are coming to linux and Unix with
> 	the expectation of ACLs.  While intelligent use of
> 	group IDs can more simply deal with _almost_ all
> 	permissions issues, and by being simpler tend to be
> 	more secure, many will prefer the quick fix ACLs
> 	provide.
> [...]
> So while demand is currently low i believe that rsync will
> need to support ACLs and EAs in the near future or it will
> become little more than a limited download tool like ftp.

A very good analysis.

While indeed currently the pure Unix area has not such great need for ACLs,
there is a prominent area of application, which are Samba servers. If you
migrate a Windows domain controller/file server to Samba you will be
confronted with ACLs. You will either have to support them or present
alternatives, and usually the users will be accustomed to using GUIs under
Windows to adjust their ACLs.

The SGI group on XFS once commented that most XFS installations are due to the
ACL support, which is needed for this reason, and I have since seen a lot of
Samba/ACL systems popping up with rising trend.

Of course there are workarounds, like extracting the ACLs into a text dump,
rsyncing that and reapplying them on the other side, but a native rsync
support possibly converting between different ACL incarnations would be more
than nice to have.

Maybe samba's code on ACL abstraction can be "stolen"? After all samba & rsync
do have a prominent subset of authors ... ;)
Axel.Thimm at
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