UNIX for Dummies Questions & Answers

#!/usr/bin/ksh
year=$1
if [ `expr $year % 100` -eq 0 -a `expr $year % 400` -eq 0 ]
then
        echo "$year is a leap year"
elif [ `expr $year % 100` -ne 0 -a `expr $year % 4` -eq 0 ]
then
        echo "$year is a leap year"
else
        echo "$year is a not leap year"
fi

function leap 
{
#  This function tells you if the argument is a leap year or not... 
if [[ $(cal ${1:-$(date '+%Y')} |egrep "^[ 0-9][0-9]| [ 0-9][0-9]$" |wc -w) -eq 365 ]] 
then 
        Leap_YN='N' 
else
        Leap_YN='Y'
fi && print ${Leap_YN} 
}