cal(1) on Linux
The text d2321b8829fd, as Debian 5.0 (Lenny), Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
displays a calendar and the date of easter
Flags it lists
-
-3 -
-J -
-e -
-j -
-m -
-o -
-p -
-s -
-w -
-y