title: Command composition in bash
body: <p>So I have the equivalent of a list of files being output by another command, and it looks something like this:</p>
  
  <pre><code>http://somewhere.com/foo1.xml.gz
  http://somewhere.com/foo2.xml.gz
  ...
  </code></pre>
  
  <p>I need to run the XML in each file through xmlstarlet, so I'm doing <code>... | xargs gzip -d | xmlstarlet ...</code>, except I want xmlstarlet to be called once for each line going into gzip, not on all of the xml documents appended to each other. Is it possible to <code>compose 'gzip -d' 'xmlstarlet ...'</code>, so that xargs will supply one argument to each of their composite functions?</p>