I had experienced difficulty getting rsnapshot to work. After joining
the rsnapshot list, responses made it clear that rsnapshot generally
needs essentially root privileges to write to backup, log and lock
files. Running as root worked fine. I suspect some digging and fiddle
would make it possible to run as a plain user for user's own files. Of
course, I was hoping to avoid such fiddle with a package that is in the
Ubuntu and Debian repositories. This could simply be that the
appropriate documentation is not visible enough -- a common issue I've
been finding lately.
Thanks to all who responded.
JN