Ask Tom. Oracle hot backup https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:894628342039 I'm assuming you DO NOT use rman (the book-keeper) but do you own backup and recovery. If so, just issue "alter database backup controlfile to trace" and backup the resulting trace file with your backup. In that file, you'll have stuff like:

-- Commands to add tempfiles to temporary tablespaces.
-- Online tempfiles have complete space information.
-- Other tempfiles may require adjustment.
ALTER TABLESPACE TEMP ADD TEMPFILE '/home/ora11gr2/app/ora11gr2/oradata/orcl/temp01.dbf'
SIZE 20971520 REUSE AUTOEXTEND ON NEXT 655360 MAXSIZE 32767M;
-- End of tempfile additions.

you won't have to remember, we'll remember..