Socket files, artype=exustar, errctl=

Hi,

what file types other than PF_UNIX sockets are known
to raise error condition SPECIALFILE with artype=exustar ?
(With Linux, ext2, ext3, reiserfs, xfs, ... ? ...)


I get haunted by messages like 

  star: '/dev/log' unsupported file type 'socket'. Not dumped.

which also lead to star exit value 254 (resp. -2) and cause
my script to raise alarm and point the user upward to
the backup protocol.
That protocol looks quite ugly by 28 of above messages.
It is intended to look appeasing because backup is about
a calm sleep.


I understand that powerful artype=exustar does not support
socket files, neither does artype=gnutar which seems to be
the default (despite the "do not" in man 1 star).
artype=star does not complain about sockets but the man page
gives me the impression that exustar is superior otherwise.

I understand that PF_UNIX sockets are supposed to be removed
on end-of-service. So after a shutdown or crash they are
dead trash anyway. A new startup of the related service will
create the socket again. (Linux: man 7 unix, "NOTES")

Unless there are any sophisticated tricks with permissions
which rely on the existence of the predecessor socket file,
i can imagine no situation where it makes sense to restore
socket files. So there is no need to backup them.


I consider to use errctl= with a file containing the line
SPECIALFILE *
In a test it worked fine for artype=exustar -acl .

Nevertheless the error condition SPECIALFILE does not
refer explicitely only to PF_UNIX socket files. 

Therefore my question : are there filetypes with exustar
which are more worth restoring but are not supported ?
(... and how about artype=gnutar ?)
I do not want to suppress messages about those other types.

Could one possibly downgrade the "type 'socket'" condition
from deferred error to a mere notification ? (Or just be
silent without errctl= file ?)

Argument driven errctl would be nice anyway, like
  errctl-line='SPECIALFILE *'
The need for a file is a bit a rupture in star's usual 
user interface. 


Have a nice day :)

Thomas