How to find the version of a Maven plugin in the project?

I'm trying to find the version of maven-wagon plugin that's being used in my project. Is there a way to find the version of a used plugin via command line?

There are several ways to do this:

1) Check the dependency tree:

To find out the libraries and versions you are using you can use the Maven dependency tree, just execute this where you have your project (pom.xml):

mvn dependency:tree -Dverbose

This is useful detect which version of an specific library your project is using, but I think it doesn't include plugins.

2) Describe the specific plugin:

If you want to know what version of an specific plugin you have installed you can do this:

mvn -Dplugin=: help:describe

mvn -Dplugin=org.codehaus.mojo:wagon-maven-plugin help:describe

This shows you something like this:

Name: Maven Wagon plugin
Description: Maven plugin that can be used to access various operations on a
  given URL using a supported maven wagon. Supports recursive upload, download,
  and list directory content functionality.
Group Id: org.codehaus.mojo
Artifact Id: wagon-maven-plugin
Version: 1.0
Goal Prefix: wagon
 
This plugin has 11 goals:
...
...

3) Check the effective pom:

Execute this:

mvn help:effective-pom

and go through the pom looking for the plugin you need to clarify, there you will find something like this:

<plugin>
   <groupId>org.codehaus.mojo</groupId>
   <artifactId>wagon-maven-plugin</artifactId>
   <version>1.0</version>
</plugin>