This example illustrates how to check properties using environment variable whether it is set or not. In this code, there are three properties; the first two are used to define source directory and destination directory. The source directory is 'src' and the destination directory is 'build'. The element <property environment="env"> is a path of jar file dependent on environment variables, and these are available only if you use <property environment="env"> before you import the property file. The following example shows how to check whether TOMCAT_HOME environment variable is set or not. If TOMCAT_HOME environment variable is set, then the output will display build successful... as given below.
But if TOMCAT_HOME environment variable is not set, then the following error message will be displayed.