title: shell_exec() not executing pdftotext command
body: <p>I installed the required library and its working in terminal but not in my php file.
  My code is :</p>
  
  <pre><code>$mypdf = shell_exec('/usr/local/bin/pdftotext test.pdf test.txt');
  echo $mypdf;
  </code></pre>
  
  <p>If I execute this command <code>/usr/local/bin/pdftotext test.pdf test.txt</code> in terminal it works fine. </p>
  
  <p>I also write my code this type : </p>
  
  <pre><code>shell_exec('/usr/local/bin/pdftotext test.pdf test.txt');
  $mypdf = file_get_contents("test.txt");
  echo $mypdf;
  </code></pre>
  
  <p>In Error Log the message is :</p>
  
  <pre><code>/usr/local/bin/pdftotext: /opt/lampp/lib/libgcc_s.so.1: version `GCC_4.2.0' not found (required by /usr/lib/i386-linux-gnu/libstdc++.so.6)
  </code></pre>