#! /bin/sh
: 'This file is in the public domain, so clarified as of' : '2006-07-17 by Arthur David Olson.'
case $#-$1 in
2-|2-0*|2-*[!0-9]*) echo "$0: wild year - $1" >&2 exit 1 ;;
esac
case $#-$2 in
2-even) case $1 in *[24680]) exit 0 ;; *) exit 1 ;; esac ;; 2-nonpres|2-nonuspres) case $1 in *[02468][048]|*[13579][26]) exit 1 ;; *) exit 0 ;; esac ;; 2-odd) case $1 in *[13579]) exit 0 ;; *) exit 1 ;; esac ;; 2-uspres) case $1 in *[02468][048]|*[13579][26]) exit 0 ;; *) exit 1 ;; esac ;; 2-*) echo "$0: wild type - $2" >&2 ;;
esac
echo “$0: usage is $0 year even|odd|uspres|nonpres|nonuspres” >&2 exit 1