title: node.js child_process doesnt work
body: <p>currently I am working on an automatic docx2pdf converter in node.js. I am using unoconv.
  When i run this command in the shell in works pretty well:</p>
  
  <pre><code>unoconv -f pdf "/opt/bitnami/apache2/htdocs/123.docx"
  </code></pre>
  
  <p>But i want to call this command from node.js, there are some modules (unoconv wrapper), but none of this worked for me. So i just want to call this command from above. I tried all solutions from <a href="https://stackoverflow.com/questions/14458508/node-js-shell-command-execution">node.js shell command execution</a> but they dont work.<br>
  Why does this code snippet doesent work for me?</p>
  
  <pre><code>                        function run_cmd(cmd, args, callBack) {
                          var spawn = require('child_process').spawn;
                          var child = spawn(cmd, args);
                          var resp = "";
  
                          child.stdout.on('data', function(buffer) {
                              resp += buffer.toString()
                          });
                          child.stdout.on('end', function() {
                              callBack(resp)
                          });
                      } // ()
                      run_cmd("unoconv", ['-f pdf "/opt/bitnami/apache2/htdocs/123.docx"'], function(text) {
                          console.log(text)
                      });
  </code></pre>
  
  <p>It dont produced output even if i run the script from pm2 as service or directly with the node command. I hope you can help me! 
  Thanks in advance</p>