Using /dev/sr0 certainly worked, thanks for pointing that out. I use modprobe sg
in rc.local and the error I mentioned occurs with the scsi address as a root user; there is no problem with permissions at the destination.
I see a discussion of this issue in German:
and my schoolboy German seems to indicate that the last post in this exchange is from Jörg Schilling himself with the promise of a fix in a new release cdrtools-3.01a18. But I cannot understand the whole thread which at least starts discussing the same error that I have found, are there any German speakers reading this thread? Changelog for the new release reports:
Fixed fine grained privilege handling for Linux. Thanks for Daniel Pielmeier from Gentoo for reporting and testing.
On the weekend I will compile the newest release and see if this definitively solves the issue...