Ant task to join multiple lines text into single line string

• Option 1: Use temp file:

      <target name="jdk-modules1">
          <exec executable="java" output="jdk.modules.tmp">
              <arg value="--list-modules"/>
          </exec>
          <loadfile property="jdk.modules" srcFile="jdk.modules.tmp">
              <filterchain>
                  <replaceregex pattern="@.*" replace=","/>
                  <striplinebreaks/>
                  <replaceregex pattern=",$" replace=""/>
              </filterchain>
          </loadfile>
          <delete file="jdk.modules.tmp" />
          <echo message="${jdk.modules}" />
      </target>
  

• Option 2: Use Javascript:

      <target name="jdk-modules2">
          <exec executable="java" outputproperty="jdk.modules">
              <arg value="--list-modules"/>
          </exec>
          <script language="javascript">
              <![CDATA[
              var value = project.getProperty('jdk.modules');
              project.setProperty('jdk.modules', value.replace(/@.*\n/g, ',').replace(/@.*/g, ''));
              ]]>
          </script>
          <echo message="${jdk.modules}"/>
      </target>
  

see also

• Replacing characters in Ant property