ant bootstrap arg1 arg2 arg3

I need to echo "arg1 arg2 arg3" so that I can call a program with those arguments

Searching the web the following should work but does not.

 <target name="bootstrap">
     <echo>${arg0} ${arg1} ${arg2} </echo>
     <!--exec executable="cmd">
        <arg value="${arg0}"/>
        <arg value="${arg1}"/>
        <arg value="${arg2}"/>
     </exec-->
 </target>

Also, any thoughts on what if the user passes in 5 args or 1 arg. I need to fail it does not not have the right number of args.

ant
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