How to make the output of a shell command available to Maven?

<profile>
  <id>update-distroVersion</id>
  <activation>
    <property>
      <name>!distroVersion</name>
    </property>
  </activation>
  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <executions>
          <execution>
            <id>echo-distroVersion-to-file</id>
            <phase>generate-resources</phase>
            <goals>
              <goal>exec</goal>
            </goals>
            <configuration>
              <executable>sh</executable>
              <arguments>
                <argument>-c</argument>
                <argument>
                  (echo -n "distroVersion="; grep -o -e [1-9] /etc/issue | head -n 1) > ${distroVersionFile}
                </argument>
              </arguments>
            </configuration>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>properties-maven-plugin</artifactId>
        <executions>
          <execution>
            <id>read-distroVersion-property</id>
            <phase>process-resources</phase>
            <goals>
              <goal>read-project-properties</goal>
            </goals>
            <configuration>
              <files>
                <file>${distroVersionFile}</file>
              </files>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</profile>