Symfony\Component\Process\Process::clearErrorOutput PHP Method

    public function clearErrorOutput()
    {
        ftruncate($this->stderr, 0);
        fseek($this->stderr, 0);
        $this->incrementalErrorOutputOffset = 0;
        return $this;
    }

 /**
  * {@inheritdoc}
  */
 public function processScript(CliScript $script)
 {
     $log = $this->getLog();
     $log->info('Executing "{script}" script', ['script' => $script->getScript()]);
     // New process, with timeout
     $process = new Process($script->getScript());
     $process->setTimeout($script->getTimeout());
     // Run process
     $process->run(function ($type, $buffer) use($log) {
         // Trim
         $buffer = trim($buffer);
         // Don't log empty output
         if (empty($buffer)) {
             return;
         }
         if (Process::OUT === $type) {
             $log->debug($buffer);
             return;
         }
         $log->error($buffer);
     });
     // Abort if process failed
     if (!$process->isSuccessful()) {
         // Remove the error output
         $process->clearErrorOutput();
         // Throw failure
         throw new ScriptFailedException(sprintf('Script "%s" has filed', $script->getScript()));
     }
 }