What day is today?
========================

I recently discovered that a unix tool that I use on a daily basis is
practically unknown to most of the people I have asked about it. This
tool is cal(1):

 $ cal
     September 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

Yes, if run without any argument, cal(1) just prints the calendar of the
current month. But it can also print the calendar of any months in any
year:

 $ cal 9 1972
     September 1972
  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

or the whole calendar of a year, if you see what I mean (i.e., if you
read the manpage). I think it is nowadays mainly forgotten because very
few people nowadays use a computer from the command line only (yes,
having a shiny calendar app is unfortunately the norm for many a "unix
enthusiast").

Just avoid to get confused with calendar(1), which will probably print
nothing at all in your system :P

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cal(1)          appeared in UNIXv5 (1974)
calendar(1)     appeared in UNIXv7 (1979)

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