title: Sending the command(s) spawned by xargs to background
body: <p>I want to know how I can send the command(s) spawned by xargs to background.
  For example, consider </p>
  
  <pre><code>find . -type f  -mtime +7 | tee compressedP.list | xargs compress
  </code></pre>
  
  <p>I tried</p>
  
  <pre><code>find . -type f  -mtime +7 | tee compressedP.list | xargs -i{} compress {} &amp;
  </code></pre>
  
  <p>.. and as unexpected, it seems to send xargs to the background instead?</p>
  
  <p>How do I make each instance of the compress command go to the background?</p>