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<h2><a name="touch">Touch</a></h2>
<h3>Description</h3>

<p>Changes the modification time of a resource and possibly creates it
at the same time. In addition to working with a single file, this Task
can also work on <a href="../Types/resources.html">resources</a> and
resource collections (which also includes directories).  Prior to Apache Ant
1.7 only FileSet or <a href="../Types/filelist.html">Filelist</a>
(since Ant 1.6) have been supported.</p>

<p>Ant uses the API of <code>java.io.File</code> to set the last
  modification time which has some limitations.  For example the
  timestamp granularity depends on the operating system and sometimes
  the operating system may allow a granularity smaller than
  milliseconds.  If you need more control you have to fall back to
  the <code>&lt;exec&gt;</code> task and native commands.</p>

<p>Starting with Ant 1.8.2 Ant will log a warning message if it fails
  to change the file modification time.  This will happen if you try
  to change the modification time of a file you do not own on many
  Unix systems, for example.</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 name of the file.</td>
    <td valign="top" align="center">Unless a nested resource collection element
       has been specified.</td>
  </tr>
  <tr>
    <td valign="top">millis</td>
    <td valign="top">Specifies the new modification time of the file
       in milliseconds since midnight Jan 1 1970.</td>
    <td valign="center" align="center" rowspan="2">No--datetime takes
       precedence, however if both are omitted the current time is assumed.</td>
  </tr>
  <tr>
    <td valign="top">datetime</td>
    <td valign="top">Specifies the new modification time of the file. The 
       special value &quot;now&quot; indicates the current time 
       (now supported since Ant 1.8).</td>
  </tr>
  <tr>
    <td valign="top">pattern</td>
    <td valign="top">SimpleDateFormat-compatible pattern string.
       Defaults to MM/DD/YYYY HH:MM AM_or_PM or MM/DD/YYYY HH:MM:SS AM_or_PM.
       <b>Since Ant 1.6.3</b></td>
    <td valign="top" align="center">No</td>
  </tr>
  <tr>
    <td valign="top">mkdirs</td>
    <td valign="top">Whether to create nonexistent parent
       directories when touching new files. <b>Since Ant 1.6.3</b></td>
    <td valign="top" align="center">No, default <i>false</i>.</td>
  </tr>
  <tr>
    <td valign="top">verbose</td>
    <td valign="top">Whether to log the creation of new files.
       <b>Since Ant 1.6.3</b></td>
    <td valign="top" align="center">No, default <i>true</i>.</td>
  </tr>
</table>
<h3>Parameters specified as nested elements</h3>
<h4>any resource collection</h4>

<p>You can use any number of nested resource collection elements to
define the resources for this task and refer to resources defined
elsewhere.  <b>Note:</b> resources passed to this task must implement
the <code>org.apache.tools.ant.types.resources.Touchable</code>
interface, this is true for all filesystem-based resources like those
returned by path, fileset ot filelist.</p>

<p>For backwards compatibility directories matched by nested filesets
will be "touched" as well, use a &lt;type&gt; selector to suppress
this.  This only applies to filesets nested into the task directly,
not to filesets nested into a path or any other resource
collection.</p>

<h4>mapper</h4>
<p><em>Since Ant 1.6.3,</em> a nested <a href="../Types/mapper.html">
    mapper</a> can be specified.  Files specified via nested
    <code>fileset</code>s, <code>filelist</code>s, or the <code>file</code>
    attribute are mapped using the specified mapper.  For each file mapped,
    the resulting files are touched. If no time has been specified and
    the original file exists its timestamp will be used.
    If no time has been specified and the original file does not exist the 
    current time is used. Since Ant 1.8 the task settings (<code>millis</code>,
    and <code>datetime</code>) have priority over the timestamp of the original
    file.</p>
<h3>Examples</h3>
<pre>  &lt;touch file=&quot;myfile&quot;/&gt;</pre>
<p>creates <code>myfile</code> if it doesn't exist and changes the
modification time to the current time.</p>
<pre>  &lt;touch file=&quot;myfile&quot; datetime=&quot;06/28/2000 2:02 pm&quot;/&gt;</pre>
<p>creates <code>myfile</code> if it doesn't exist and changes the
modification time to Jun, 28 2000 2:02 pm (14:02 for those used to 24
hour times).</p>
<pre>  &lt;touch datetime=&quot;09/10/1974 4:30 pm&quot;&gt;
    &lt;fileset dir=&quot;src_dir&quot;/&gt;
  &lt;/touch&gt;</pre>
<p>changes the modification time to Oct, 09 1974 4:30 pm of all files and directories 
  found in <code>src_dir</code>. </p>
<pre>  &lt;touch file=&quot;myfile&quot; datetime=&quot;06/28/2000 2:02:17 pm&quot;/&gt;</pre>
<p>creates <code>myfile</code> if it doesn't exist and changes the
modification time to Jun, 28 2000 2:02:17 pm (14:02:17 for those used to 24
hour times), if the filesystem allows a precision of one second - a
time close to it otherwise.</p>
<pre>  &lt;touch file=&quot;foo&quot;&gt;
    &lt;mapper type=&quot;glob&quot; from=&quot;foo&quot; to=&quot;bar&quot; /&gt;
  &lt;/touch&gt;
</pre>
<p>creates <code>bar</code> if it doesn't exist and changes the
modification time to that of <code>foo</code>.</p>

<pre>  &lt;touch file=&quot;foo&quot; datetime=&quot;now&quot;&gt;
    &lt;mapper type=&quot;regexp&quot; from=&quot;^src(.*)\.java&quot; to=&quot;shadow\1.empty&quot; /&gt;
  &lt;/touch&gt;
</pre>
<p>creates files in the <code>shadow</code> directory for every java file in the
   <code>src</code> directory if it doesn't exist and changes the modification
   time of those files to the current time.</p>


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