All conditions to test are specified as nested elements, for a complete list see here.
Examples
<condition property="javamail.complete"> <and> <available classname="javax.activation.DataHandler"/> <available classname="javax.mail.Transport"/> </and> </condition>sets the property javamail.complete if both the JavaBeans Activation Framework and JavaMail are available in the classpath.
<condition property="isMacOsButNotMacOsX"> <and> <os family="mac"/> <not> <os family="unix"/> </not> </and> </condition>sets the property isMacOsButNotMacOsX if the current operating system is MacOS, but not MacOS X - which Ant considers to be in the Unix family as well.
<condition property="isSunOSonSparc"> <os name="SunOS" arch="sparc"/> </condition>sets the property isSunOSonSparc if the current operating system is SunOS and if it is running on a sparc architecture.