gcal binary package in Ubuntu Bionic amd64

 Gcal displays a calendar for a month or a year, eternal holiday lists
 and fixed date lists, in many ways. The program correctly omits the
 dates that were skipped when the current Gregorian calendar replaced
 the earlier Julian calendar.
 .
 Apart from the usual and well known calendar functions like the
 output of a month or a year calendar sheet, or the output of an eternal
 holiday list, Gcal offers the facility to display fixed dates on the
 day of their occurrence and to remind or inform the user about them.
 So it is possible for users to receive an on-screen notification, at bootup
 or login, of all holidays or appointments which take place on that day.
 Notification by electronic mail is also possible.

Source package