Calculates the Date of Mardi Gras from `ncal -e`

mardi-gras.sh

#!/bin/bash

function usage {
	echo "$0 [-n NUMBER] [YEAR]"
}

date -j &> /dev/null
if [ $? -eq 0 ]; then
	# OS X
	function mardigras {
		date -j -v -47d -f '%B %e %Y' "$( ncal -e $1 )" +'%Y-%m-%d'
	}
else
	# LINUX
	function mardigras {
		date -d "$( ncal -e $1 ) -47 days" +'%Y-%m-%d'
	}
fi

declare -i NUMBER YEAR i

NUMBER=1

while getopts :hn: OPT; do
	case "$OPT" in
		h)
			usage
			exit 0
			;;
		n)
			NUMBER=$OPTARG
			shift; shift
			;;
		:)
			usage
			exit 1
			;;
	esac
done

YEAR=${1:-$( date +%Y )}

for (( i=0; i<NUMBER; ++i)); do
	mardigras $(( i + YEAR ))
done