Unix shell script: run task on specific weekday.

I have a request from user that he want to run a report from server automatically on third Monday every month, I use the following Unix shell script to take care of it.

#RUNDATE=`cal |awk 'NR == 3 { print $2; }'`
#if [ "$RUNDATE" == '' ]; then
NUMBERFIELD=`cal |awk 'NR == 3 { print NF; }'`
if [ $NUMBERFIELD -lt 6 ]; then
        RUNDATE=`cal |awk 'NR == 6 { print $2; }'`
        else RUNDATE=`cal |awk 'NR == 5 { print $2; }'`
fi
echo $RUNDATE
TODAY=`date +%e`
if [ $TODAY == $RUNDATE ]; then
echo "Today `date +%Y%m%d` is run day!"
else
echo "Today `date +%Y%m%d` is NOT run day!"
echo "run date should be at ${RUNDATE}th, which is the thrid Monday for each month."
exit
fi

...

sqlplus -s / as sysdba <<- EOF

        SET MARKUP HTML ON ENTMAP ON SPOOL ON PREFORMAT OFF

        SET ECHO OFF TERM OFF VERIFY OFF FEEDBACK OFF TRIMS OFF PAGESIZE 999

        set markup html on

        spool  filename.html

...

EOF

if [ -f  filename.html  ]

then

{

uuencode filename.html newname.html|mail -s "subject" email@emailserver.com

}

else

echo "error"

fi