Ant task to run an Ant target only if a file exists?

Is there an ANT Task that would execute a block only if a given file exists? I have the problem that I have a generic ant script that should do some special processing but only if a specific configuration file is present.

Available and Condition

<target name="check-abc">
    <available file="abc.txt" property="abc.present"/>
</target>

<target name="do-if-abc" depends="check-abc" if="abc.present">
    ...
</target> 

This might make a little more sense from a coding perspective (available with ant-contrib: http://ant-contrib.sourceforge.net/):

<target name="someTarget">
    <if>
        <available file="abc.txt"/>
        <then>
            ...
        </then>
        <else>
            ...
        </else>
    </if>
</target>

Since Ant 1.8.0 there's apparently also resourceexists

From http://ant.apache.org/manual/Tasks/conditions.html

> Tests a resource for existance. since > Ant 1.8.0 > > The actual resource to test is > specified as a nested element. > > An example: > > > >

I was about rework the example from the above good answer to this question, and then I found this

> As of Ant 1.8.0, you may instead use > property expansion; a value of true > (or on or yes) will enable the item, > while false (or off or no) will > disable it. Other values are still > assumed to be property names and so > the item is enabled only if the named > property is defined. > > Compared to the older style, this > gives you additional flexibility, > because you can override the condition > from the command line or parent > scripts: > > > > > > > >

from the ant manual at http://ant.apache.org/manual/properties.html#if+unless

Hopefully this example is of use to some. They're not using resourceexists, but presumably you could?.....

I think its worth referencing this similar answer: https://stackoverflow.com/a/5288804/64313

Here is a another quick solution. There are other variations possible on this using the <available> tag:

# exit with failure if no files are found
<property name="file" value="${some.path}/some.txt" />
<fail message="FILE NOT FOUND: ${file}">
    <condition><not>
        <available file="${file}" />
    </not></condition>
</fail>

Check Using Filename filters like DB_*/**/*.sql

Here is a variation to perform an action if one or more files exist corresponding to a wildcard filter. That is, you don't know the exact name of the file.

Here, we are looking for "*.sql" files in any sub-directories called "DB_*", recursively. You can adjust the filter to your needs.

NB: Apache Ant 1.7 and higher!

Here is the target to set a property if matching files exist:

<target name="check_for_sql_files">
    <condition property="sql_to_deploy">
        <resourcecount when="greater" count="0">
            <fileset dir="." includes="DB_*/**/*.sql"/>
        </resourcecount>
    </condition>
</target>

Here is a "conditional" target that only runs if files exist:

<target name="do_stuff" depends="check_for_sql_files" if="sql_to_deploy">
	<!-- Do stuff here -->
</target>

You can do it by ordering to do the operation with a list of files with names equal to the name(s) you need. It is much easier and direct than to create a special target. And you needn't any additional tools, just pure Ant.

<delete>
    <fileset includes="name or names of file or files you need to delete"/>
</delete>

See: FileSet.