These Unix Spotlights are about some Unix commands that you might not know exist and a few things you can do with them.

TL;DR: cal prints a calendar.

I love this command.  While it's extremely easy to find and check out a calendar on the internet, on your desktop, on your phone — if you're already in terminal, you know, why not print out a sweet calendar?

$ cal

    January 2020
Su Mo Tu We Th Fr Sa
          1  2  3  4
 5  6  7  8  9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30 31

Yeah, but what's gonna happen next month?   You can do cal month year.  

$ cal 2 2020

   February 2020
Su Mo Tu We Th Fr Sa
                   1
 2  3  4  5  6  7  8
 9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29

You can do future years, you can leave out the month to get a full year's calendar.  You can also do the pivoted version if you want, which is good if you're like, "Ugh, what are the dates for every Tuesday this February?  

$ ncal 2 2020

    February 2020
Su     2  9 16 23
Mo     3 10 17 24
Tu     4 11 18 25
We     5 12 19 26
Th     6 13 20 27
Fr     7 14 21 28
Sa  1  8 15 22 29

Try cal 9 1752.