How to execute tasks conditionally using the maven-antrun-plugin?

First, according to Maven 1.x website, the current stable release for maven 1.x is version 1.1, not 1.4. Second, there is no AntRun Plugin version 1.7 and, to my knowledge, this is a Maven 2 plugin. Third, the syntax you are using seems very similar to Using Attributes which, again, is about Maven 2.

So, I may be missing something but, this is very confusing and you should maybe clarify these points in your question.

Anyway, as you explicitly mentioned Maven 1, I'll try to answer. If I remember well, I would write a custom goal and use Jelly's core:if or core:when. To do so, provide something like this in maven.xml:

<project xmlns:j="jelly:core" xmlns:ant="jelly:ant">
  <goal name="my-goal">
    <j:if test="${environment == 'PROD'}">
      <ant:xxx .../>
    </j:if>
  </goal>
</project>

I'm really not sure of the syntax, all this Maven 1 stuff is just too far away, and I didn't test it (I'm too lazy to install Maven 1). But I guess you will. The scripting reference may help you.

To be honest, I really hope you have a good reason to prefer Maven 1.x over Maven 2.x :)

UPDATE: It appears that the OP is actually using Maven 2 so I'll update my question accordingly. To implement the desired behavior, you could use Ant-contrib's if task as shown below:

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-antrun-plugin</artifactId>
        <version>1.3</version>
        <executions>
          <execution>
            <phase>compile</phase>
            <goals>
              <goal>run</goal>
            </goals>
            <configuration>
              <tasks>
                <taskdef resource="net/sf/antcontrib/antcontrib.properties"
                  classpathref="maven.plugin.classpath" />
                <if>
                  <equals arg1="${foo}" arg2="bar" />
                  <then>
                    <echo message="The value of property foo is bar" />
                  </then>
                  <else>
                    <echo message="The value of property foo is not bar" />
                  </else>
                </if>
              </tasks>
            </configuration>
          </execution>
        </executions>
        <dependencies>
          <dependency>
            <groupId>ant-contrib</groupId>
            <artifactId>ant-contrib</artifactId>
            <version>20020829</version>
          </dependency>
        </dependencies>
      </plugin>
    </plugins>
  </build>

And then call mvn compile -Dfoo=bar (this is just an example).

But, all this is not the "maven way" to do things. Now that I understand a bit better what you are trying to do (but not entirely as you didn't explain your ultimate goal), I think that using build profiles would be more appropriate and, having read your own answer, I think that you are over complicating things (and that you are on the wrong path).

I understand that you are a Maven beginner but I'd suggest to try to use it though instead of falling back on Ant or you won't get the benefits of it. Also, when opening a question, instead of asking for a specific solution, you should rather explain your general problem, you'll get better answers. Here, I can't provide more guidance as I don't know what you are really trying to achieve.

You don't need to use AntContrib after maven-antrun-plugin 1.5 that uses <target> instead of <tasks> according to plugin usage. This tag works in the same way as , but in this one you can add conditions like the example below.

<properties>
    <execute.my.target>true</execute.my.target>
</properties>

<build>
    ...
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-antrun-plugin</artifactId>
            <executions>
                <execution>
                    <id>config</id>
                    <phase>package</phase>
                    <goals>
                        <goal>run</goal>
                    </goals>
                    <configuration>
                        <!-- this target will be executed always -->
                        <target>
                            <echo message="Hello there, I'm a simple target" />
                        </target>
                        
                        <!-- 
                            This target will be executed if and only if
                            the property is set to true
                        -->
                        <target name="my-target" if="execute.my.target">
                            <echo message="Conditional target..." />
                        </target>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
    ...
</build>

The code above always executes the first target, but the second target depends on a property value. You can configure it for a parent and a sub-module project too, defining the plugin on <pluginsManagement> tag and calling some properties at the sub-modules, then calling the plugin.

Update: Be sure to use the if parameter without ${}, since it can cause troubles mentioned in the comments section.