Note the manual page shows both cal and ncal in the same page and has:
cal [-3hjy] [-A number] [-B number] [[month] year] cal [-3hj] [-A number] [-B number] -m month [year] ncal [-3bhjJpwySM] [-A number] [-B number] [-s country_code] [[month] year] ncal [-3bhJeoSM] [-A number] [-B number] [year] ncal [-CN] [-H yyyy-mm-dd] [-d yyyy-mm]
showing that the -M option is only for ncal, not plain cal.
Dave
Note the manual page shows both cal and ncal in the same page and has:
cal [-3hjy] [-A number] [-B number] [[month] year]
cal [-3hj] [-A number] [-B number] -m month [year]
ncal [-3bhjJpwySM] [-A number] [-B number] [-s country_code] [[month] year]
ncal [-3bhJeoSM] [-A number] [-B number] [year]
ncal [-CN] [-H yyyy-mm-dd] [-d yyyy-mm]
showing that the -M option is only for ncal, not plain cal.
Dave