Run a shell command in backgroud using PHP

function.php

<?php
 /**
   * Run a command in background (Windows and linux \o/)
   *
   * @param wait wait for the command to terminate
   * @author dalexandre
   * @author jbenoist
   * @since 24/02/2009
   * @update 19/08/2009
   * @param String $cmd
   */
  public function runCmdInBackground($cmd, $outputfile = null, $wait = false)
  {
    if($outputfile === null)
      $outputfile = sfConfig::get('sf_root_dir') . '/log/cmdBackground_'.date('Y_m_d_h_i_s_').rand(0, 10).'.log';
    elseif ($outputfile === false)
      $outputfile = '/dev/null';

    if(substr(php_uname(), 0, 7) != 'Windows')
    {
      $wait = $wait ? '' : (' >> ' . $outputfile . ' &');

      exec('nohup ' . $cmd . $wait);
    }
    else
    {
      $wait = $wait ? ' /WAIT ' : ' ';

      pclose(popen('start /B' . $wait . $cmd . ' >> ' . $outputfile, 'r'));
    }
  }