"I assumed they can merged into 16 but they were not after upgrading my system."
Yeah... that's a pretty unfounded assumption.
Fortunately, your data might be salvageable, if the new system has separate -- and populated -- directories for 12, 13 and 14. Were any of the source system Postgresql instances running when you ran rsync?
If not, then you can install the old versions of Postgresql in parallel with 16, and then run pg_upgrade.
I used “rsync” in Linux to backup the the entire directory that contained data for 12,13 and 15. The last 15 was gone after upgrading to 16 with Ubuntu 22.04. I assumed they can merged into 16 but they were not after upgrading my system.
I try to restore all data from /var/lib/pgsql/15/main, but do not know how and have not found hits from your web as detailed below. Could you provide a tip for that?Thanks. Regards
Your search for restore data from /var/lib/pgsql/ returned no hits.