khal:tldr:4a561

The given command is related to the usage of "khal", a command-line calendar application for Unix-like systems. Here's what each part of the command does:

1. khal: It is the main command used to interact with the "khal" calendar application.

2. new: This subcommand indicates that you want to create a new calendar event.

3. -a ${personal}: This flag specifies the calendar to which the new event should be added. In this case, the calendar named "personal" is chosen. Depending on your configuration, the name "personal" may refer to a specific calendar file or backend.

4. ${2020-09-08}: This specifies the date of the event. The format used here is Year-Month-Day. In this case, it represents September 8, 2020.

5. ${18:00}: This represents the start time of the event. The format used here is Hour:Minute. In this case, it represents 6:00 PM.

6. ${18:30}: This represents the end time of the event. Similar to the previous part, it represents 6:30 PM.

7. "${Dentist appointment}": This is the title or summary of the event enclosed within double quotes. In this case, the event is titled "Dentist appointment".

Combining all these parts, the command is telling the "khal" application to create a new event in the "personal" calendar on September 8, 2020, from 6:00 PM to 6:30 PM with the title "Dentist appointment". The exact functionality and behavior may depend on your specific "khal" calendar configuration and setup.