Shell Programming and Scripting

Hi,

I am beginner writing shell script i am using korn shell. I wrote shell script through which i am passing system date as parameter to build.xml file but i need to write a function when i pass systemdate as parameter the function has to return its respective quarterly date . Can any one help me in that plllzzzz.I need to get quarterly date when i pass sys date



#!/bin/ksh
#ident "%W%"


# loaddnt.ksh

if [ $# -lt 2 ] ; then
echo "You have not provided any date , so SystemDate will be considered for this job"

PERIOD_DATE=`date +'20060930'`
fi
SCRIPT_NAME=`basename $0 | cut -d. -f 1`
starttime=`date "+%D %H:%M:%S"`
PARAMS=$*
#PERIOD_DATE=$2
export PERIOD_DATE
TASK_NAME=$1
export PERIOD_DATE