How to store the entire XML into a variable using shell script

Question

I have the below XML file, and I just want to store the XML file into variable using Shell script.

 <?xml version="1.0" encoding="UTF-8"?>
  <testng-results skipped="0" failed="0" total="10" passed="10">
    <test-method status="FAIL" is-config="true" duration-ms="4"
        started-at="2018-08-16T21:43:38Z" finished-at="2018-08-16T21:43:38Z">
        <params>
            <param index="0">
                <value>                <![CDATA[org.testng.TestRunner@31c2affc]]>
                </value>
            </param>
        </params>
        <reporter-output>
        </reporter-output>
     </test-method> <!-- setParameter -->
  </testng-results>

I want to assign this XML values into variable using shell script. Any leads?