divbzero • 14 hours ago

cal doesn’t offer an option to use the 1582 reform date, but looks like it does handle the 1752 adoption in Great Britain correctly:

  $ cal 9 1752
     September 1752
  Su Mo Tu We Th Fr Sa
         1  2 14 15 16
  17 18 19 20 21 22 23
  24 25 26 27 28 29 30

1
madcaptenor • 12 hours ago

But `ncal` does offer that option. Here's October 1582 in "Italy", which didn't exist back then:

  $ ncal -sIT 10 1582
      October 1582      
  Mo  1 18 25         
  Tu  2 19 26         
  We  3 20 27         
  Th  4 21 28         
  Fr 15 22 29         
  Sa 16 23 30         
  Su 17 24 31
France apparently took a couple months to get on board (or maybe just to find out):

  $ncal -sFR 12 1582
      December 1582     
  Mo     3 20 27      
  Tu     4 21 28      
  We     5 22 29      
  Th     6 23 30      
  Fr     7 24 31      
  Sa  1  8 25         
  Su  2  9 26
`ncal -p` gives a list of the country codes it accepts. (These are current countries so it's a bit ahistorical for, say, Germany.)

Sadly they don't implement the weird thing Sweden did in the early 18th century: https://en.wikipedia.org/wiki/Swedish_calendar