sup(1) on Linux
The text 21c41d531a5b, as Debian 5.0 (Lenny), Debian 4.0 (Etch) shipped it.
software upgrade protocol
Flags it lists
-
-B -
-D -
-E -
-K -
-N -
-O -
-P -
-S -
-Z -
-a -
-b -
-d -
-e -
-f -
-k -
-l -
-m -
-o -
-s -
-t -
-u -
-v -
-z