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  <title>If and Unless on all tasks/nested elements</title>
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<body>
  <h1><a name="if_and_unless">If And Unless</a></h1>

  <p>Since Ant 1.9.1 it is possible to add if and unless attributes on all tasks and nested elements using special namespaces.</p>

  <p>In order to use this feature you need to add the following namespace declarations</p>
  <blockquote><pre>
    xmlns:if=&quot;ant:if&quot;
    xmlns:unless=&quot;ant:unless&quot;
    </pre>
  </blockquote>

  <p>The if and unless namespaces support the following 3 conditions :
  <ul>
    <li>true</li>true if the value of the attribute evaluates to true
    <li>blank</li>true if the value of the attribute is null or empty
    <li>set</li>true if the specified property is set
  </ul></p>

<blockquote>
<pre>
&lt;project name=&quot;tryit&quot;
 xmlns:if=&quot;ant:if&quot;
 xmlns:unless=&quot;ant:unless&quot;
&gt;
 &lt;exec executable=&quot;java&quot;&gt;
   &lt;arg line=&quot;-X&quot; if:true=&quot;${showextendedparams}&quot;/&gt;
   &lt;arg line=&quot;-version&quot; unless:true=&quot;${showextendedparams}&quot;/&gt;
 &lt;/exec&gt;
 &lt;condition property=&quot;onmac&quot;&gt;
   &lt;os family=&quot;mac&quot;/&gt;
 &lt;/condition&gt;
 &lt;echo if:set=&quot;onmac&quot;&gt;running on MacOS&lt;/echo&gt;
 &lt;echo unless:set=&quot;onmac&quot;&gt;not running on MacOS&lt;/echo&gt;
&lt;/project&gt;
</pre>
</blockquote>

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