Cal

Cal is a command line utility that will output a calendar for the desired month/year. It's simple and accurate with a few useful features.

By default, Cal will display the current year. You can provide a month and year, a month, or just a year. You can also change the number of calendars per row in your display with the -n switch. See the examples below for a more through description.

This is a single executable JAR file. While you will need Java installed, there is no need to install this program. Just download the JAR file, please it somewhere convenient, and execute it from the command line:

java -jar cal.jar

The Homepage provides more detailed information and instructions.
https://github.com/frossm/cal