In both cases, the timeline directory must reside in a filesystem
cabale of hard links.
+The source specification is a directory to be backed up optionally
+followed by colon separated, one or more subtree glob paths to
+exclude. As an example, "/home:*/.cache:guest/Pictures" would declare
+source directory tree "/home" but excluding all user's ".cache" sub
+trees and also excluding the "guest" user's "Pictures" sub tree.
+
== timeliner-backup
*timeliner-backup* is a companion script that normally is set up as a