title: xargs doesn't recognize "-n1" when used with "-I%"
body: <p>When invoking <code>xargs</code> with only <code>-n1</code>, xargs executes a separate <code>echo</code> command for every item:</p>
  
  <pre><code>$ echo 1 2 | xargs -n1
  1
  2
  </code></pre>
  
  <p>But when using <code>-n1</code> with the <code>-I</code> option, which passes the string to be replaced to <code>xargs</code>, it passes all the arguments to a single <code>echo</code> command, effectively ignoring<code>-n1</code>:</p>
  
  <pre><code>$ echo 1 2 | xargs -n1 -I% echo %
  1 2
  </code></pre>
  
  <p>My goal is to execute an arbitrary command with different arguments:</p>
  
  <pre><code>$ echo 1 2 | xargs -n1 -I% mycommand %
  # What I want to achieve
  mycommand 1
  mycommand 2
  </code></pre>
  
  <p>but I'm quite baffled by the behavior I'm seeing, so:</p>
  
  <ol>
  <li>Why <code>xargs</code> seemingly ignore <code>-n1</code>?</li>
  <li>What is the correct way to do what I am trying to? Note that I don't want to deal with any files while doing so.</li>
  </ol>