maven-exec-plugin throws exception for no apparent reason

Question

I type the following in a Windows shell in the root of a Maven project that contains a class with a

public static void main(String[] args)

method that I'd like to run.

mvn exec:java -Dexec.mainClass="com.spp.config.main.SqlGeneratorHarness" -e

The class exists and is compiled in that package (i.e., target/classes/com/spp/config/main/SqlGeneratorHarness.class).

I see...

+ Error stacktraces are turned on.  
[INFO] Scanning for projects...  
[INFO] Searching repository for plugin with prefix: 'exec'.  
[INFO] ------------------------------------------------------------------------  
[ERROR] BUILD FAILURE  
[INFO] ------------------------------------------------------------------------  
[INFO] Invalid task '.mainClass=com.spp.config.main.SqlGeneratorHarness': you must specify a valid 
       lifecycle phase, or a goal in the format plugin:goal or pluginGroupId:pluginArtifactId:pluginVersion:goal
[INFO] ------------------------------------------------------------------------
[INFO] Trace org.apache.maven.BuildFailureException: Invalid task' .mainClass=com.spp.config.main.SqlGeneratorHarness': you must specify 
       a valid lifecycle phase, or a goal in the format plugin:goal or pluginGroupId:pluginArtifactId:pluginVersion:goal
       at org.apache.maven.lifecycle.DefaultLifecycleExecutor.getMojoDescriptor(DefaultLifecycleExecutor.java:1830)
       at org.apache.maven.lifecycle.DefaultLifecycleExecutor.segmentTaskListByAggregationNeeds(DefaultLifecycleExecutor.java:462)
       at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:175)
       at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
       at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
       at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
       at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
       at java.lang.reflect.Method.invoke(Method.java:597)
       at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
       at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
       at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
       at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
[INFO] ------------------------------------------------------------------------
[INFO] Total time: < 1 second
[INFO] Finished at: Tue Sep 27 14:33:52 PDT 2011
[INFO] Final Memory: 3M/122M
[INFO] ------------------------------------------------------------------------

I've tried variations like

mvn exec:exec -Dexec.executable="java" [...]

and

mvn org.codehaus.mojo:exec-maven-plugin:1.2.1:java [...]

to no avail. What gives?

I'm running Maven 2.2.1, Java JDK 1.6.0_27 on Windows 7 Enterprise 64-bit.

A snippet from my pom.xml for the exec-maven-plugin is...

<plugin> 
   <groupId>org.codehaus.mojo</groupId> 
   <artifactId>exec-maven-plugin</artifactId> 
   <version>${exec-maven-plugin.version}</version> 
</plugin> 

where the version is set in the <properties>

Answer 1

So... revisiting this... if you use Windows PowerShell, you will get the exception I originally reported. If, however, you use cmd.exe, then you should be able to run the class with the command as I posted (with or without wrapping double-quotes).