Thanks for the reply.
Here’s what is happening:
First off, I’m using Ubuntu 18.04, which does not include the /etc/rc.local file, so the install instructions need revision for later versions of Ubuntu.
Second, the client backend “urbackupclientbackend” can start and run as a systemctl service, which runs as the root user, which causes the urbackupclientgui client shell command to prompt for the sudo password in order to enable the urbackupclientgui to setup paths. I can write a work around for this.
I have it working now, but the instructions are not accurate to this type of install, and I might add the admin documentation is not written at all well despite a likely well-intended effort. You can glean lots of things from it, but it is a seriously confusing document without good flow and outline.
Also, the URL “https://www.urbackup.org/documentation.html” looks like the markdown used to generate the HTML link for the admin manual states “PDF” but links to the HTML page where the PDF can be downloaded. Also very confusion. There are others, but I’ll stop here.
I do applaud the effort to build an open-source client/server system like this, it’s got awesome potential, but what makes or breaks such a great effort is having documentation that is far below the effort to create the system in the first place.
Bottom line is I have it working now.