I have the test0.py below. I expect to see 'abcd' showing in the notepad window: --------- import subprocess as sp p0 = sp.Popen('notepad.exe', stdin=sp.PIPE) p0.communicate(input=b'abcd') --------- But nothing happens. The notepad is completely empty. What have I missed? --Jach PS. I am using python 3.4 on Windows Vista