Symlink Task

## Symlink

### Description

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.

FileSets are used to select a set of links to record, or a set of property files to create links from.

### Parameters

Attribute | Description | Required
action | The type of action to perform, may be "single", "record", "recreate" or "delete". | No, defaults to single.
link | The name of the link to be created or deleted. Note 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 `${basedir}/some-path` as its value. | required for action="single" or "delete". Ignored in other actions.
resource | The resource the link should point to. | required for action="single". Ignored in other actions.
linkfilename | The name of the properties file to create in each included directory. | required for action="record". Ignored in other actions.
overwrite | Overwrite existing links or not. | No; defaults to false.
failonerror | Stop build if true, log a warning message, but do not stop the build, when the an error occurs if false. | No; defaults to true.

### Parameters specified as nested elements

#### fileset

FileSets 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.

### Examples

Make a link named "foo" to a resource named "bar.foo" in subdir:

      <symlink link="${dir.top}/foo" resource="${dir.top}/subdir/bar.foo"/>

Record all links in subdir and it's descendants in files named "dir.links"

      <symlink action="record" linkfilename="dir.links">
         <fileset dir="${dir.top}" includes="subdir/**"/>
      </symlink>

Recreate the links recorded in the previous example:

      <symlink action="recreate">
         <fileset dir="${dir.top}" includes="subdir/**/dir.links"/>
      </symlink>

Delete a link named "foo":

     <symlink action="delete" link="${dir.top}/foo"/>

Java 1.2 and earlier: 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.

LIMITATIONS: 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 `ln -s <linkname> <resourcename>` 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 canonical resource name. Therefore the link: `link --> subdir/dir/../foo.bar` will be recorded as `link=subdir/foo.bar` and restored as `link --> subdir/foo.bar`