Saturn provides you with a CLI interface to calendaring much in the way
taskwarrior does with tasks. It also provides you with several methods to
query and notify yourself of important appointments.

It can act standalone or integrate fully with Google Calendar, but it
does not support CalDAV.

Saturn provides also a TUI as a separate program, sui will present a calendar
in a terminal window and allow you to interact with it in similar ways to
saturn.

This package contains both the CLI and TUI tools.