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With mavenSW, an environment variable is treated as a property, where the property name begins with "env.". Thus, an environment variable such as %M2_HOME% can be accessed via ${env.M2_HOME}.

The maven-antrun-plugin:run goal can be used to run AntSW tasks. We can use the "echo" Ant task to display a value of a property. The following fragment of a pom.xml file binds the antrun:goal to the validate build lifecycle phase. It then uses the "echo" Ant task to display the values of 3 environment variables: COMPUTERNAME, M2_HOME, and Path.

Fragment of pom.xml to display values of 3 environment variables

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-antrun-plugin</artifactId>
				<version>1.1</version>
				<executions>
					<execution>
						<phase>validate</phase>
						<goals>
							<goal>run</goal>
						</goals>
						<configuration>
							<tasks>
								<echo>Displaying 3 environment variables</echo>
								<echo>[COMPUTERNAME] ${env.COMPUTERNAME}</echo>
								<echo>[M2_HOME] ${env.M2_HOME}</echo>
								<echo>[Path] ${env.Path}</echo>
							</tasks>
						</configuration>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

Performing a "mvn validate" on my "mytest" project generates the following console output:

Console output of 'mvn validate' on 'mytest' project

[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building mytest
[INFO]    task-segment: [validate]
[INFO] ------------------------------------------------------------------------
[INFO] [antrun:run {execution: default}]
[INFO] Executing tasks
     [echo] Displaying 3 environment variables
     [echo] [COMPUTERNAME] YOSEMITE
     [echo] [M2_HOME] C:\dev\apache-maven-2.0.8
     [echo] [Path] C:\dev\jdk1.6.0_04\bin\..\jre\bin\client;C:\dev\jdk1.6.0_04\bin\..\jre\bin;C:\dev\cygwin\bin;C:\dev\jdk1.6.0_04\bin;C:\dev\apache-maven-2.0.8\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\hp\bin\Python;c:\Program Files\Common Files\Roxio Shared\DLLShared\;c:\Program Files\Common Files\Roxio Shared\9.0\DLLShared\
[INFO] Executed tasks
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ------------------------------------------------------------------------
[INFO] Total time: < 1 second
[INFO] Finished at: Mon Feb 11 12:38:15 PST 2008
[INFO] Final Memory: 2M/4M
[INFO] ------------------------------------------------------------------------

As you can see, the values of the 3 environment variables are displayed in the console output.

The "mytest" project's full pom.xml file is shown here.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.maventest</groupId>
	<artifactId>mytest</artifactId>
	<packaging>jar</packaging>
	<version>1.0-SNAPSHOT</version>
	<name>mytest</name>
	<url>http://maven.apache.org</url>
	<dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>3.8.1</version>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>commons-lang</groupId>
			<artifactId>commons-lang</artifactId>
			<version>2.3</version>
			<scope>compile</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-antrun-plugin</artifactId>
				<version>1.1</version>
				<executions>
					<execution>
						<phase>validate</phase>
						<goals>
							<goal>run</goal>
						</goals>
						<configuration>
							<tasks>
								<echo>Displaying 3 environment variables</echo>
								<echo>[COMPUTERNAME] ${env.COMPUTERNAME}</echo>
								<echo>[M2_HOME] ${env.M2_HOME}</echo>
								<echo>[Path] ${env.Path}</echo>
							</tasks>
						</configuration>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

</project>