code: public function execute()
      {
          $base = $this->generateCommand();
          foreach ($this->document as $name => $doc) {
              /* @var $doc Document */
              if ($doc->getPassword()) {
                  $command = sprintf(
                              '%s --password=%s',
                              $base,
                              $doc->getPassword()
                  );
              } else {
                  $command = $base;
              }
              $command = sprintf('%s %s', $command, escapeshellarg($doc->getPath()));
              if ($this->logger) {
                  $this->logger->addInfo(sprintf(
                  'Tika command: "%s"',
                  $command
                  ));
              }
  
              $process = new Process($command);
              $process->run();
  
              if (!$process->isSuccessful()) {
                  throw new \InvalidArgumentException($process->getErrorOutput());
              }
  
              $content = $process->getIncrementalOutput();
  
              $doc->setRawContent($content);
              if ($this->config->getMetadataOnly()) {
                  $this->loadMetadata($doc, $content);
              } else {
                  if (in_array($this->config->getOutputFormat(), array('xml', 'html'))) {
                      $this->loadDocument($doc, $content);
                  } else {
                      $doc->setContent($content);
                  }
              }
          }
  
          return $this;
      }
docs: Execute
  
  @return Wrapper