------
 Usage
 ------
 John Casey
 Maria Odea Ching
 Vincent Siveton
 ------
 2010-01-21
 ------

 ~~ Licensed to the Apache Software Foundation (ASF) under one
 ~~ or more contributor license agreements.  See the NOTICE file
 ~~ distributed with this work for additional information
 ~~ regarding copyright ownership.  The ASF licenses this file
 ~~ to you under the Apache License, Version 2.0 (the
 ~~ "License"); you may not use this file except in compliance
 ~~ with the License.  You may obtain a copy of the License at
 ~~
 ~~   http://www.apache.org/licenses/LICENSE-2.0
 ~~
 ~~ Unless required by applicable law or agreed to in writing,
 ~~ software distributed under the License is distributed on an
 ~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 ~~ KIND, either express or implied.  See the License for the
 ~~ specific language governing permissions and limitations
 ~~ under the License.

~~ NOTE: For help with the syntax of this file, see:
~~ http://maven.apache.org/doxia/references/apt-format.html

Usage

 Below are the different goals and the minimalist configurations of the Help Plugin.

* The <<<help:active-profiles>>> Goal

  The <<<{{{./active-profiles-mojo.html}active-profiles}}>>> goal is used to discover which profiles have been
  applied to the projects currently being built. For each project in the build session, it will output a list of
  profiles which have been applied to that project, along with the source of the profile (POM, <<<settings.xml>>>
  or <<<profiles.xml>>>).

  You can execute this goal using the following command:

+-----+
# mvn help:active-profiles
+-----+

 <<Note>>: you could also use the <<<output>>> parameter to redirect output to a file.

* The <<<help:all-profiles>>> Goal

 The <<<{{{./all-profiles-mojo.html}all-profiles}}>>> goal is used to discover all available profiles under the
 current project.

  You can execute this goal using the following command:

+-----+
# mvn help:all-profiles
+-----+

 <<Note>>: you could also use the <<<output>>> parameter to redirect output to a file.

* The <<<help:describe>>> Goal

  The <<<{{{./describe-mojo.html}describe}}>>> goal is used to discover information about Maven plugins. Given either
  a <<<plugin>>> or a <<<groupId>>>, an <<<artifactId>>> and optionally a <<<version>>>, the mojo will lookup that
  plugin and output details about it. If the user also specifies which <<<mojo>>> to describe, the <<<describe>>>
  mojo will limit output to the details of that mojo, including parameters.

  You can execute this goal using the following command:

+-----+
# mvn help:describe -DgroupId=org.somewhere -DartifactId=some-plugin -Dversion=0.0.0
+-----+

 <<Note>>: you could also use the <<<output>>> parameter to redirect output to a file.

  Refer to {{{./examples/describe-configuration.html}Configuring Describe Goal}} for more information about its
  configuration.

* The <<<help:effective-pom>>> Goal

  The <<<{{{./effective-pom-mojo.html}effective-pom}}>>> goal is used to make visible the POM that results from the
  application of interpolation, inheritance and active profiles. It provides a useful way of removing the guesswork
  about just what ends up in the POM that Maven uses to build your project. It will iterate over all projects in the
  current build session, printing the effective POM for each.

  You can execute this goal using the following command:

+-----+
# mvn help:effective-pom
+-----+

 <<Note>>: you could also use the <<<output>>> parameter to redirect output to a file.

* The <<<help:effective-settings>>> Goal

  The <<<{{{./effective-settings-mojo.html}effective-settings}}>>> goal is used to view the settings that Maven
  actually uses to run the build. These settings are a result of merging the global file with the user's file,
  with the user's file taking precedence.

  You can execute this goal using the following command:

+-----+
# mvn help:effective-settings
+-----+

 <<Note>>: you could also use the <<<output>>> parameter to redirect output to a file.

* The <<<help:system>>> Goal

  The <<<{{{./system-mojo.html}system}}>>> goal is used to view the system information like system properties and
  environment variables.

  You can execute this goal using the following command:

+-----+
# mvn help:system
+-----+

 <<Note>>: you could also use the <<<output>>> parameter to redirect output to a file.

* The <<<help:evaluate>>> Goal

  You could use this interactive goal to evaluate some Maven expressions. To do it, just call the
  {{{./evaluate-mojo.html}help:evaluate}} goal:

+-----+
# mvn help:evaluate -Dartifact=org.apache.maven.plugins:maven-help-plugin
...
[INFO] [help:evaluate]
[INFO] Enter the Maven expression i.e. ${project.groupId} or 0 to exit?:
${project.artifactId}
[INFO]
maven-help-plugin
[INFO] Enter the Maven expression i.e. ${project.groupId} or 0 to exit?:
${project.none}
[INFO]
null object or invalid expression
...
+-----+

 The <<<artifact>>> parameter refers to ask expressions on the artifact POM. If omitted, the evaluate goal uses the current
 pom.

 You could ask for all Maven expressions listed in the Javadoc of the 
 {{{/ref/current/maven-core/apidocs/org/apache/maven/plugin/PluginParameterExpressionEvaluator.html}
 <<<PluginParameterExpressionEvaluator>>>}} class.