cal(1) on Linux
The text 97a20aa40d85, as Debian 6.0 (Squeeze) shipped it.
displays a calendar and the date of Easter
Flags it lists
-
-3 -
-J -
-M -
-S -
-e -
-h -
-j -
-m -
-o -
-p -
-s -
-w -
-y