jdate(1) on Linux
The text 311661b014a4, as Debian 12 (Bookworm) shipped it.
manual page for jdate
Flags it lists
-
--access -
--date -
--gregorian -
--help -
--jalali -
--reference -
--rfc-2822 -
--universal -
--utc -
--version -
-R -
-V -
-a -
-d -
-g -
-h -
-j -
-r -
-u