catDocker.xml

<tool id="catdc" name="Concatenate datasets (in docker)" version="1.0.0">
    <description>tail-to-head</description>
    <requirements>
        <container type="docker">busybox:ubuntu-14.04</container>
    </requirements>
    <command><![CDATA[
echo "Galaxy slots passed through contain as \$GALAXY_SLOTS" &&
cat '$input1'
#for $q in $queries
    '${q.input2}'
#end for
> '$out_file1' &&
echo 'Work dir output' > working_file
    ]]></command>
    <inputs>
        <param name="input1" type="data" label="Concatenate Dataset"/>
        <repeat name="queries" title="Dataset">
            <param name="input2" type="data" label="Select" />
        </repeat>
    </inputs>
    <outputs>
        <data name="out_file1" format="input" metadata_source="input1"/>
        <data name="out_file2" format="txt" from_work_dir="working_file" />
    </outputs>
    <tests>
    </tests>
    <help>
    </help>
</tool>