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<title>Symlink Task</title>
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<h2><a name="symlink">Symlink</a></h2>
<h3>Description</h3>
<p> Manages symbolic links on Unix based platforms. Can be used to
make an individual link, delete a link, create multiple links from properties files,
or create properties files describing links in the specified directories.
Existing links are not overwritten by default.
<p><a href="../Types/fileset.html">FileSet</a>s are used to select a
set of links to record, or a set of property files to create links from. </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">action</td>
<td valign="top">The type of action to perform, may be "single",
"record", "recreate" or "delete".</td>
<td valign="top" align="center">No, defaults to single.</td>
</tr>
<tr>
<td valign="top">link</td>
<td valign="top">The name of the link to be created or deleted.<br/>
<b>Note</b> this attribute is resolved against the current
working directory rather than the project's basedir for
historical reasons. It is recommended you always use an
absolute path or a path like <code>${basedir}/some-path</code>
as its value.
</td>
<td valign="center" align="center" >required for
action="single" or "delete". Ignored in other actions.</td>
</tr>
<tr>
<td valign="top">resource</td>
<td valign="top">The resource the link should point to.</td>
<td valign="top" align="center">required for action="single". Ignored in other actions.</td>
</tr>
<tr>
<td valign="top">linkfilename</td>
<td valign="top">The name of the properties file to create in
each included directory.</td>
<td valign="top" align="center">required for action="record".
Ignored in other actions.</td>
</tr>
<tr>
<td valign="top">overwrite</td>
<td valign="top">Overwrite existing links or not.</td>
<td valign="top" align="center">No; defaults to false.</td>
</tr>
<tr>
<td valign="top">failonerror</td>
<td valign="top">Stop build if true, log a warning message, but do not stop the build,
when the an error occurs if false.
</td>
<td valign="top" align="center">No; defaults to true.</td>
</tr>
</table>
<h3>Parameters specified as nested elements</h3>
<h4>fileset</h4>
<p><a href="../Types/fileset.html">FileSet</a>s
are used when action = "record" to select directories and linknames to be recorded.
They are also used when action = "recreate" to specify both the name of the property
files to be processed, and the directories in which they can be found. At least one
fileset is required for each case.</p>
<h3>Examples</h3>
<p> Make a link named "foo" to a resource named "bar.foo" in subdir:</p>
<pre>
<symlink link="${dir.top}/foo" resource="${dir.top}/subdir/bar.foo"/>
</pre>
<p> Record all links in subdir and it's descendants in files named
"dir.links"</p>
<pre>
<symlink action="record" linkfilename="dir.links">
<fileset dir="${dir.top}" includes="subdir/**"/>
</symlink>
</pre>
<p> Recreate the links recorded in the previous example:</p>
<pre>
<symlink action="recreate">
<fileset dir="${dir.top}" includes="subdir/**/dir.links"/>
</symlink>
</pre>
<p> Delete a link named "foo":
<pre>
<symlink action="delete" link="${dir.top}/foo"/>
</pre>
<p><strong>Java 1.2 and earlier:</strong> Due to limitations on executing system
level commands in Java versions earlier than 1.3 this task may have difficulty
operating with a relative path in ANT_HOME. The typical symptom is an
IOException where Apache Ant can't find /some/working/directory${ANT_HOME}/bin/antRun
or something similar. The workaround is to change your ANT_HOME environment
variable to an absolute path, which will remove the /some/working/directory portion
of the above path and allow ant to find the correct commandline execution script.
<p><strong>LIMITATIONS:</strong> Because Java has no direct support for
handling symlinks this task divines them by comparing canonical and
absolute paths. On non-unix systems this may cause false positives.
Furthermore, any operating system on which the command
<code>ln -s <linkname> <resourcename></code> is not a valid
command on the command line will not be able to use action="single" or
action="recreate". Action="record" and action=delete should still work. Finally,
the lack of support for symlinks in Java means that all links are recorded as
links to the <strong>canonical</strong> resource name. Therefore the link:
<code>link --> subdir/dir/../foo.bar</code> will be recorded as
<code>link=subdir/foo.bar</code> and restored as
<code>link --> subdir/foo.bar</code></p>
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