title: cat: can't open '/tmp/drive/P0.RAW': No such file or directory
body: <p>The script pasted below causes the following error:</p>
  
  <blockquote>
    <p>cat: can't open '/tmp/drive/P0.RAW': No such file or directory</p>
  </blockquote>
  
  <p>It looks like the script does not properly evaluate <code>$N</code> for the filename.
  How <code>$N</code> be made to evaluate so the file name is something like P01L.RAW, P02L.RAW, etc.?</p>
  
  <pre><code>N=1
  until [ $N -ge 10 ]; do
      cat bmpheader.bmp /tmp/drive/P0$NL.RAW &gt; ./P0$NL.bmp
      ./quality_metric_test ./P0$NL.bmp
      N=$((N + 1))
  done
  </code></pre>