i have a file in the project dirictory. i wnt to print it using qprocess

i tried like this but not working
Qt Code: 
  1. void RptPrintBarCodeDlg::pbnOk_clicked()
  2. {
  3.     QString line;
  4.     line="hello world";
  5.     QFile file("print.txt");
  6.     if ( file.open( IO_WriteOnly ) ) 
  7.     {
  8.         QTextStream stream( &file );
  9.         stream<<line;
  10.         file.close();
  11.         QProcess *printbarcode = new QProcess(this);
  12.         printbarcode->setWorkingDirectory(QDir::current());
  13.         printbarcode->addArgument("cat");
  14.         printbarcode->addArgument("print.txt");
  15.         printbarcode->addArgument(">");
  16.         printbarcode->addArgument("/dev/lp0");
  17.  
  18.         if(!printbarcode->start())
  19.         {
  20.             QMessageBox::information(this,"Error", "process not started" ,"Ok");
  21.         }
  22.     }
  23.     else
  24.     {
  25.         QMessageBox::information(this,"Error", "File is not opened" ,"Ok");
  26.  
  27.     }
  28. }
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can anybody help me