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<h2><a name="checksum">Checksum</a></h2>
<h3>Description</h3>
<p>
Generates checksum for files.  This task can also be used to
perform checksum verifications.
</p>
<h3>Parameters</h3>
<table border="1" cellpadding="2" cellspacing="0">
  <tr>
    <td valign="top"><b>Attribute</b></td>
    <td valign="top"><b>Description</b></td>
    <td align="center" valign="top"><b>Required</b></td>
  </tr>
  <tr>
    <td valign="top">file</td>
    <td valign="top">The file to generate checksum for.</td>
    <td valign="top" align="center">One of either <var>file</var> or
    at least one nested fileset element.</td>
  </tr>
  <tr>
    <td valign="top">algorithm</td>
    <td valign="top">Specifies the algorithm to be used to
      compute the checksum. Defaults to &quot;MD5&quot;.
      Other popular algorithms like &quot;SHA&quot; may be used
      as well.
    </td>
    <td valign="top" align="center">No</td>
  </tr>
  <tr>
    <td valign="top">provider</td>
    <td valign="top">Specifies the provider of the algorithm.</td>
    <td valign="top" align="center">No</td>
  </tr>
  <tr>
    <td valign="top">fileext</td>
    <td valign="top">The generated checksum file's name will be the
    original filename with &quot;.&quot; and fileext added to it.
    Defaults to the algorithm name being used.
    </td>
    <td valign="top" align="center">No</td>
  </tr>
  <tr>
    <td valign="top">property</td>
    <td valign="top">Specifies the name of the property to be set
    with the generated checksum value.  This cannot be specified
    when fileext is being used or when the number of files
    for which checksums is to be generated is greater than 1.
    </td>
    <td valign="top" align="center">No</td>
  </tr>
  <tr>
    <td valign="top">overwrite</td>
    <td valign="top">Overwrite existing files even if the destination
      files are newer. Defaults to &quot;no&quot;.</td>
    <td valign="top" align="center">No</td>
  </tr>
  <tr>
    <td valign="top">verifyproperty</td>
    <td valign="top">Specifies the name of the property to be set
    with &quot;true&quot; or &quot;false&quot; depending upon whether
    the generated checksum matches the existing checksum.  When
    this is set, the generated checksum is not written to a file or
    property, but rather, the content of the file or property is used to
    check against the generated checksum.
    <td valign="top" align="center">No</td>
  </tr>
</table>
<h3>Parameters specified as nested elements</h3>

<h4>fileset</h4>
 <p>
 <a href="../CoreTypes/fileset.html">FileSets</a> are used to select files to
 generate checksums for.
 </p>

<h3>Examples</h3>
<p><b>Example 1</b></p>
<pre>&lt;checksum file=&quot;foo.bar&quot;/&gt;</pre>
Generates a MD5 checksum for foo.bar and stores the checksum in the destination file
foo.bar.MD5.  foo.bar.MD5 is overwritten only if foo.bar is newer than itself.

<p><b>Example 2</b></p>
<pre>&lt;checksum file=&quot;foo.bar&quot; forceOverwrite=&quot;yes&quot;/&gt;</pre>
Generates a MD5 checksum for foo.bar and stores the checksum in foo.bar.MD5.
If foo.bar.MD5 already exists, it is overwritten.

<p><b>Example 3</b></p>
<pre>&lt;checksum file=&quot;foo.bar&quot; property=&quot;foobarMD5&quot;/&gt;</pre>
Generates a MD5 checksum for foo.bar and stores it in the Project Property foobarMD5.

<p><b>Example 4</b></p>
<pre>&lt;checksum file=&quot;foo.bar&quot; verifyProperty=&quot;isMD5ok&quot;/&gt;</pre>
Generates a MD5 checksum for foo.bar, compares it against foo.bar.MD5 and sets
isMD5ok to either true or false, depending upon the result.

<p><b>Example 5</b></p>
<pre>&lt;checksum file=&quot;foo.bar&quot; algorithm=&quot;SHA&quot; fileext=&quot;asc&quot;/&gt;</pre>
Generates a SHA checksum for foo.bar and stores the checksum in the destination file
foo.bar.asc.  foo.bar.asc is overwritten only if foo.bar is newer than itself.

<p><b>Example 6</b></p>
<pre>
&lt;checksum file=&quot;foo.bar&quot; property=&quot;${md5}&quot; verifyProperty=&quot;isEqual&quot;/&gt;
</pre>
Generates a MD5 checksum for foo.bar, compares it against the value of the property
md5, and sets isEqual to either true or false, depending upon the result.

<p><b>Example 7</b></p>
<pre>
&lt;checksum&gt;
  &lt;fileset dir=&quot;.&quot;&gt;
    &lt;include name=&quot;foo*&quot;/&gt;
  &lt;/fileset&gt;
&lt;/checksum&gt;
</pre>
Works just like Example 1, but generates a .MD5 file for every file that begins with the name foo.

<p><b>Example 8</b></p>
<pre>
&lt;condition property=&quot;isChecksumEqual&quot;&gt;
  &lt;checksum&gt;
    &lt;fileset dir=&quot;.&quot;&gt;
      &lt;include name=&quot;foo.bar&quot;/&gt;
    &lt;/fileset&gt;
  &lt;/checksum&gt;
&lt;/condition&gt;
</pre>
Works like Example 4, but only sets isChecksumEqual to true, if the
checksum matches - it will never be set to false.  This example
demonstrates use with the Condition task.


<h3>Note:</h3>
When working with more than one file, if condition and/or verifyproperty is used,
the result will be true only if the checksums matched correctly for all files being
considered.

<hr><p align="center">Copyright &copy; 2001 Apache Software Foundation. All rights
Reserved.</p>

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