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<h2 id="touch">Touch</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>
(<em>since Ant 1.6</em>) were 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><em>Since Ant 1.8.2</em>, a warning message is logged upon failure 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 class="attr">
  <tr>
    <th>Attribute</th>
    <th>Description</th>
    <th>Required</th>
  </tr>
  <tr>
    <td>file</td>
    <td>The name of the file.</td>
    <td>Unless a nested resource collection element has been specified</td>
  </tr>
  <tr>
    <td>millis</td>
    <td>Specifies the new modification time of the file in milliseconds since midnight Jan 1
      1970.</td>
    <td rowspan="2">No; <var>datetime</var> takes precedence, however if both are omitted then
      current time is assumed</td>
  </tr>
  <tr>
    <td>datetime</td>
    <td class="left">Specifies the new modification time of the file.  <em>Since Ant 1.8</em>, the
      special value <q>now</q> indicates the current time.</td>
  </tr>
  <tr>
    <td>pattern</td>
    <td>SimpleDateFormat-compatible pattern string using the current locale. <em>Since Ant
      1.6.3</em></td>
    <td>No; defaults to <q>MM/dd/YYYY hh:mm a</q> or <q>MM/dd/yyyy hh:mm:ss a</q> using the US
      locale.</td>
  </tr>
  <tr>
    <td>mkdirs</td>
    <td>Whether to create nonexistent parent directories when touching new files. <em>Since Ant
      1.6.3</em></td>
    <td>No; default <q>false</q></td>
  </tr>
  <tr>
    <td>verbose</td>
    <td>Whether to log the creation of new files.  <em>Since Ant 1.6.3</em></td>
    <td>No; default <q>true</q></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. <strong>Note</strong>: 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 <var>type</var> 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. <em>Since
Ant 1.8</em>, the task settings (<var>millis</var>, and <var>datetime</var>) have priority over the
timestamp of the original file.</p>
<h3>Examples</h3>

<pre>&lt;touch file=&quot;myfile&quot;/&gt;</pre>
<p>creates <samp>myfile</samp> 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 <samp>myfile</samp> 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 time).</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 <samp>src_dir</samp>.</p>

<pre>&lt;touch file=&quot;myfile&quot; datetime=&quot;06/28/2000 2:02:17 pm&quot;/&gt;</pre>
<p>creates <samp>myfile</samp> 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 time), if the filesystem allows a precision of one
second&mdash;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 <samp>bar</samp> if it doesn't exist and changes the modification time to that
of <samp>foo</samp>.</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 <samp>shadow</samp> directory for every <samp>.java</samp> file in
the <samp>src</samp> directory if it doesn't exist and changes the modification time of those files
to the current time.</p>

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