cal doesn't work with any options. cal -M returns

Usage: cal [general options] [-jy] [[month] year]
       cal [general options] [-j] [-m month] [year]
       ncal -C [general options] [-jy] [[month] year]
       ncal -C [general options] [-j] [-m month] [year]
       ncal [general options] [-bhJjpwySM] [-H yyyy-mm-dd] [-s country_code] [[month] year]
       ncal [general options] [-bhJeoSM] [year]
General options: [-31] [-A months] [-B months] [-d yyyy-mm]

as does most/all other options I try to enter. Same issue if I try ncal -CM.

Cal is such a simple utility that I'm surprised there would be any issue with it. It just came installed on my 19.10 version of kubuntu. apt doesn't even know about the existence of cal. Is there anything that can be done?

  • 3
    As you can see from the usage message, -M isn't a valid option for cal - only for ncal. Can you confirm that ncal -M gives the same message? What is the output of type -a cal? Commented Jul 4, 2020 at 2:16
  • ``` cal is /usr/bin/cal cal is /usr/bin/cal ```
    – alec
    Commented Jul 4, 2020 at 2:18
  • ncal -C works. But trying to add -M results in the same usage options being returned.
    – alec
    Commented Jul 4, 2020 at 2:21
  • The -m option needs an argument (a month number or name) - did you give it one? Commented Jul 4, 2020 at 2:26
  • sorry, typo, -M was what I used, not lowercase m. And I just discovered that -b is what I want, not -C.
    – alec
    Commented Jul 4, 2020 at 2:27

1 Answer 1


The man page doesn't explain clearly what options can be used with ncal and what options can be used with cal. It just illustrates them. The SYNOPSIS of the man page and the usage message returned from entering an invalid option illustrate the valid combinations of options that exist and each command, cal and ncal -- these do not show -C being used in combination with -M because that combination is invalid and simply does not work.

To get the cal program to print Monday as the first day of the week, the command is ncal -bM.

  • ncal on macos 10.10 has no -bM; ncal -s DE does print weeks starting on Monday, vertical. See also calendar.py.
    – denis
    Commented Aug 25, 2020 at 15:23

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