#!/bin/sh
# grgdif
# calculates the days difference between two dates and reports 
# the number days as grg1 - grg2 
# usage grgdif grg1 grg2
# where gregorian date is in the form yyyymmdd

usage () {
echo "Usage:"
echo " grgdif grg1 grg2"
echo ""
echo " Calculate day difference between"
echo " two gregorian dates (grg1 - grg2)"
echo " where a gregorian date is in the form of yyyymmdd."
	}

if [ $# != 2 ]
then
usage
exit
fi
# convert each date to julian
grg1=$1
grg2=$2
jul1=`ymd2yd $grg1`
jul2=`ymd2yd $grg2`

# calculate the answer using juldif
res=`juldif $jul1 $jul2`

# and output the results
echo $res