How to concatenate files in ant

[debic]

I need to do something like 

type a.txt b.txt c.txt >merged.txt

I tried the follwoing code but it doesn't seem to be working. Has anyone
done something
like that before? Thx.

                <copy tofile="merged.txt">
                        <fileset dir="." >
                                <patternset>
                                 <include name="aa"/>
                                 <include name="bb"/>
                                 <include name="cc"/>
                                </patternset>
                        </fileset>
                </copy>