Please help me to create a shell script that can parse the below XML and send a string back adding all XML values.
<RequestBillsRsp version="1.0"><BillSummaryData><AgreementNumberFull>13-WY-8425-2</AgreementNumberFull><AgreementNumberAbbr>WY84252</AgreementNumberAbbr><LineOfBusiness>F</LineOfBusiness><CompanyCode>0005</CompanyCode><UniqDigit/><StateCode/><UnitID>13</UnitID><DueDate>04/12/2012</DueDate><BillAmount>282.00</BillAmount><StateAgentCode>131533</StateAgentCode><AgentName>DAN CUTHBERT</AgentName><AgentPhoneNumber>(847)228-6620</AgentPhoneNumber><PayableFlag>N</PayableFlag><ACHPayableFlag>N</ACHPayableFlag><BillROCode>01</BillROCode><PayableMessage>001</PayableMessage><BillDate>20090824</BillDate><SeqNum>0615882</SeqNum><PlcyDispName>PRIOVOLOS, TASOS & SOFIA</PlcyDispName><MailingZipcode/><RiskDesc>18214 S SPRING MEADOWS DR</RiskDesc><AnyAmountPayableFlag>N</AnyAmountPayableFlag><ACHAnyAmountPayableFlag>N</ACHAnyAmountPayableFlag></BillSummaryData><AddressInfo><AddressOne/><AddressTwo/><City/><State/><Zip/></AddressInfo><PayerName/><messages rc="00"/></RequestBillsRsp>