title: output of one command is argument of another
body: <p>Is there any way to fit in 1 line using the pipes the following:</p>
  
  <p>output of </p>
  
  <pre><code>sha1sum $(xpi) | grep -Eow '^[^ ]+'
  </code></pre>
  
  <p>goes instead of 456</p>
  
  <pre><code>sed 's/@version@/456/' input.txt &gt; output.txt
  </code></pre>