title: SSIS Foreach loop through text files with "crosswlk" in the name
body: <p>In my Foreach loop I only want to process files that have <strong>crosswlk</strong> in the filename.  Unfortunately this is in the middle of the filename and I can't do <strong>crosswlk.pgp</strong>.</p>
  
  <p>I have Googled this a bunch and most solutions say to do some C# in a script task to accomplish this.  It seems like I should be able to do this in the Foreach container, maybe in the Collection area with Expressions.  But I'm having troubles finding any information about the various Properties in the Property Expressions Editor.  What's the difference between the Name, <code>FileSpec</code> and <code>FileNameRetrieval</code> properties?</p>
  
  <p>I thought I could do something like:</p>
  
  <pre><code>Property: Name
  Expression: `FINDSTRING(@[User::SourceFilename],"crosswlk",1) &gt; 0`
  </code></pre>
  
  <p>To me that's saying only process files where the filename has <strong>crosswlk</strong> in it.  But that's not working.  I did notice the word <strong>crosswlk</strong> always starts at the 13th character in the filename so I tried using substring, but no luck there either.  </p>
  
  <p>Is there a way to do filter the filenames this (or another) way, or is using C# the only way?  Thanks very much!</p>