<tool id="headtail" name="head-or-tail">
  <description>of a file</description>
  <command>$headortail -n $nline $input > $out_file1 </command>
  <inputs>
    <param name="input" format="txt" type="data" label="Original file"/>
    <param name="nline" size="10" type="integer" value="10" label="Number of lines to output"/>
    <param name="headortail" type="select" label="Head or Tail">
        <option value="head" selected="true">head</option>
        <option value="tail">tail</option>
    </param>
  </inputs>
  <outputs>
    <data format="input" name="out_file1" />
  </outputs>
  <tests>
    <test>
      <output name="out_file1" file="testmap.head"/>
      <param name="input" value="test.map" ftype="TXT"/>
      <param name="n" value="10"/>
      <param name="headortail"  value="head" />
    </test>
  </tests>
  <help>

**What it does**

This is a wrapper of the unix head/tail command, which is used to show lines at the beginning or at the end of a file.  

  </help>
</tool>