ssh-add(1) on macOS
The text a6a9ca003d2c, as Mac OS X 10.5.2, Mac OS X 10.5.1, Mac OS X 10.5 shipped it.
adds RSA or DSA identities to the authentication agent
Flags it lists
-
-D -
-K -
-L -
-X -
-c -
-d -
-e -
-k -
-l -
-s -
-t -
-x