PyQt example: How to run a command and disply its stdout

import os
import sys 
from PyQt4.QtCore import * 
from PyQt4.QtGui import * 
 
def main(): 
    app = QApplication(sys.argv) 
    w = MyWindow() 
    w.show() 
    sys.exit(app.exec_()) 
 
class MyWindow(QWidget): 
    def __init__(self, *args): 
        QWidget.__init__(self, *args) 
 
        # create objects
        label = QLabel(self.tr("Enter command and press Return"))
        self.le = QLineEdit()
        self.te = QTextEdit()

        # layout
        layout = QVBoxLayout(self)
        layout.addWidget(label)
        layout.addWidget(self.le)
        layout.addWidget(self.te)
        self.setLayout(layout) 

        # create connection
        self.connect(self.le, SIGNAL("returnPressed(void)"),
                     self.run_command)

    def run_command(self):
        cmd = str(self.le.text())
        stdouterr = os.popen4(cmd)[1].read()
        self.te.setText(stdouterr)
  
if __name__ == "__main__": 
    main()