Phing combine and minify js example

<!-- combine and minify js. add all js files to the first exec command. -->
 <target name="compress_js" description="Combine javascript files to one file, compress with yui compressor.">
  <tstamp />
  <exec logoutput="true" checkreturn="true"
        command="cat ${basedir}/assets/js/bootstrap.js ${basedir}/assets/js/bootstrap2.js > ${basedir}/build/tmp.js" />
  <jsMin targetDir="${basedir}/assets/cache" suffix=".min.${DSTAMP}" failOnError="false">
    <fileset dir="${basedir}/build">
      <include name="tmp.js"/>
    </fileset>
  </jsMin>
  <exec logoutput="true"
        command="rm ${basedir}/build/tmp.js" />
 </target>