title: Pipe two different outputs into a command that takes two inputs
body: <p>It seems like this should be pretty easy but it's not intuitive to me how to do it.  I have two files and I want to diff their first columns (this is an example, I'm sure there are other ways to do this).  So I might do <code>cut -d, -f1 file1 &gt; tmp1</code>, <code>cut -d, -f1 file2 &gt; tmp2</code> and then <code>diff tmp1 tmp2</code>.  But I want to do it without using the tmp files.</p>
  
  <p>An example of the sort of thing I'm expecting would be <code>((cut -d, -f1 file1), (cut -d, -f1 file2)) &gt; diff</code> but this is not real code.</p>
  
  <p>Is there a way to do this?</p>