khal
A text-based calendar and scheduling application for the command line.
TLDR
Start khal on interactive mode
$ ikhal
Print all events scheduled in personal calendar for the next seven days
$ khal list -a [personal] [today] [7d]
Print all events scheduled not in personal calendar for tomorrow at 10:00
$ khal at -d [personal] [tomorrow] [10:00]
Print a calendar with a list of events for the next three months
$ khal calendar
Add new event to personal calendar
$ khal new -a [personal] [2020-09-08] [18:00] [18:30] "[Dentist appointment]"