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Ant Conditions

Ant conditions are used to control the flow of a build file based on certain conditions. They can be used to perform tasks conditionally, skip certain parts of the build, or execute different tasks based on different conditions. Here are some examples of how to use Ant conditions:

  • Using the "if" task to execute a task conditionally:
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<if>
  <equals arg1="${env.OS}" arg2="Windows_NT"/>
  <then>
    <echo message="This is a Windows system."/>
  </then>
</if>

This checks if the value of the "OS" environment variable is equal to "Windows_NT". If it is, the "echo" task is executed and outputs the message "This is a Windows system.".

  • Using the "unless" attribute to skip a task if a certain condition is met:
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<exec executable="myapp" unless="build.failed"/>

This skips the "exec" task if the "build.failed" property has been set elsewhere in the build file or by an external source.

  • Using the "isset" task to execute a task only if a property has been set:
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<isset property="app.name"/>
<echo message="The name of the app is ${app.name}" if="app.name"/>

This checks if the "app.name" property has been set. If it has, the "echo" task is executed and outputs the message "The name of the app is [value of app.name property]".

  • Using the "or" condition to execute a task if any of several conditions are met:
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<or>
  <equals arg1="${env.OS}" arg2="Windows_NT"/>
  <equals arg1="${env.OS}" arg2="Linux"/>
  <equals arg1="${env.OS}" arg2="MacOSX"/>
  <then>
    <echo message="This is a supported operating system."/>
  </then>
  <else>
    <echo message="This is not a supported operating system."/>
  </else>
</or>

This checks if the value of the "OS" environment variable is equal to "Windows_NT", "Linux", or "MacOSX". If it is, the "echo" task is executed and outputs the message "This is a supported operating system.".

These are just a few examples of how to use Ant conditions. Conditions are a powerful feature of Ant that can help you create flexible and customizable build scripts



Next: Ant Filesets

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