- backup:
openhab-cli backup [filename] - restore:
openhab-cli restore [filename]
For the most part, assuming you have not modified “system” files like those in /var/lib/openhab2 you should be able to restore across versions at least as far back as OH 2.1. If you have modified files in /var/lib/openhab2 by hand (e.g. modified the log4j2 config) you might need to double check that those files have not changed.
You would probably want to Clear the Cache after the restore after the restore if you are restoring from an older OH version.
We do not live in an ideal world. To meet that requirement we would have to basically freeze OH as it is now. No new features, no significant bug fixes, no moving forward. Ultimately the problem is we don’t have enough volunteers who are both willing and able to put forth the effort that meeting this would require.
But I can say that for the files that are officially sanctioned to be edited by the users (i.e. those files in /etc/openhab2) for the most part they can be ported from at least as far back as 2.1 with little to no required changes. Whether or not there are changes required depends on whether there were problems with Rules syntax that were not properly detected in the earlier versions (the Rules syntax checker got more strict which is a good thing) or if there were significant additions or changes to a given binding and you have text based Things.