Ant build files are written in XML, which does not allow declaring variables as you do in your favorite programming language. However, as you may have imagined, it would be useful if Ant allowed declaring variables such as project name, project source directory, etc.

Ant uses the property element which allows you to specify properties. This allows the properties to be changed from one build to another or from one environment to another.

By default, Ant provides the following pre-defined properties that can be used in the build file

Sr.No.1-ant.file

The full location of the build file.

Sr.No.2-ant.version

The version of the Apache Ant installation.

Sr.No.3-basedir

The basedir of the build, as specified in the basedir attribute of the project element.

Sr.No.4- ant.java.version

The version of the JDK that is used by Ant.

Sr.No.5-ant.project.name

The name of the project, as specified in the name attribute of the project element.

Sr.No.6-ant.project.default-target

The default target of the current project.

Sr.No.7-ant.project.invoked-targets

Comma separated list of the targets that were invoked in the current project.

Sr.No.8-ant.core.lib

The full location of the Ant jar file.

Sr.No.9-ant.home

The home directory of Ant installation.

Sr.No.10-ant.library.dir

The home directory for Ant library files - typically ANT_HOME/lib folder.

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Ant also makes the system properties (Example: file.separator) available to the build file.

In addition to the above, the user can define additional properties using the property element. The following example shows how to define a property called sitename

<?xml version = "1.0"?>
<project name = "Hello World Project" default = "info">
<property name = "sitename" value = "www.tutorialspoint.com"/>

<target name = "info">
<echo>Apache Ant version is ${ant.version} - You are at ${sitename} </echo>
</target>
</project>

Running Ant on the above build file produces the following output

C:\>ant
Buildfile: C:\build.xml

info: [echo] Apache Ant version is Apache Ant(TM) version 1.8.2
compiled on December 20 2010 - You are at [ Register or Signin to view external links. ]

BUILD SUCCESSFUL
Total time: 0 seconds
C:\>