title: xargs does not read line by line properly
body: <p>Here is my current commands which i use:</p>
  
  <pre><code>xargs -n 1 -P 100 php b &lt;links
  </code></pre>
  
  <p>I have a script 'b' and a file with links in 'links' and sometimes I don't know why this doesn't work correctly and add to every line symbol "?"
  like this:</p>
  
  <pre><code>root     19714  0.0  1.0  19880  5480 pts/2    R+   11:19   0:00 php b http://www.google.com?
  root     19715  0.0  0.9  19524  4892 pts/2    R+   11:19   0:00 php b http://www.alexa.com?
  root     19716  0.0  1.0  19880  5496 pts/2    R+   11:19   0:00 php b http://www.amazon.com?
  </code></pre>
  
  <p>see to the end of the ps-aux result line is "?" symbol and my file doesn't contain that... but not all the times... what could be the problem?</p>