import subprocess
subprocess.call("date")

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:Python27libsubprocess.py", line 168, in call
    return Popen(*popenargs, **kwargs).wait()
  File "C:Python27libsubprocess.py", line 390, in __init__
    errread, errwrite)
  File "C:Python27libsubprocess.py", line 640, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified