#Purpose: Validate a date
#Usage: chkdate year month day
#
if [ $# -eq 0 ]; then
echo Usage: chkdate year month day
exit 0
fi
year=$1; month=$2; day=$3; extra=$4
if [[ "$extra" != "" ]]; then
# Too much data!
echo Usage: chkdate year month day
exit 1
fi
if [[ "$year" == "" || "$month" == "" || "$day" == "" ]]; then
# Not enough data!
echo Usage: chkdate year month day
exit 2
fi
if [[ ! ( $year =~ ^[0-9]+$ && $month =~ ^[0-9]+$ && $day =~ ^[0-9]+$ ) ]]; then
# Date not numeric!
echo Usage: chkdate year month day
exit 3
fi
#Remove leading zeros if any
year=$(echo "$year" | bc)
month=$(echo "$month" | bc)
day=$(echo "$day" | bc)
if [[ $year -lt 1 || $year -gt 9999 || $month -lt 1 || $month -gt 12 || $day -lt 1 || $day -gt 31 ]]; then
# Date out of range!
echo Usage: chkdate year month day
exit 4
fi
if [[ ( $month == 1 || $month == 3 || $month == 5 || $month == 7 || $month == 8 || $month == 10 || $month == 12 ) && $day -gt 31 ]]; then
# Invalid day!
echo Usage: chkdate year month day
exit 5
fi
if [[ ( $month == 4 || $month == 6 || $month == 9 || $month == 11 ) && $day -gt 30 ]]; then
# Invalid day!
echo Usage: chkdate year month day
exit 6
fi
if [[ $month == 2 && $(($year%100)) == 0 ]]; then
if [[ $(($year%400)) == 0 ]]; then
isLeapYear=1
else
isNotLeapYear=1
fi
elif [[ $month == 2 && $(($year%4)) == 0 ]]; then
isLeapYear=1
else
isNotLeapYear=1
fi
if [[ $month == 2 && $day -gt 28 && $isNotLeapYear ]]; then
# Not Leap year!
echo Usage: chkdate year month day
exit 7
fi
if [[ $month == 2 && $day -gt 29 && $isLeapYear ]]; then
# Invalid day!
echo Usage: chkdate year month day
exit 8
fi
while [[ $# -ne [1-8] ]]; do
cal << ( $year $month $day )
fi
echo $year $month $day is valid date
