[Tutor] Replacing keyboard input to EXE file

[Alun Griffiths]

Hi

I have a legacy (FORTRAN) program called POLY.EXE which asks the user 
interactively for three inputs (file names) from the keyboard.  I 
would like to run this program in batch and tried to replace the 
interactive prompts with file names stored in a separate file using 
this Python script:

import subprocess

try:
     poly_file = file("poly_files.txt","r")
except:
     print "Could not open input file"
else:
     x = subprocess.Popen(args="poly.exe", stdin=poly_file)
     x.wait()

poly_files.txt contains the three file names as follows:

polyin.dat
polyout.dat
polyout.plt

On execution, I get these error messages
Traceback (most recent call last):
   File "C:/Projects/Active/Alun/test_poly.py", line 4, in -toplevel-
     x = subprocess.Popen(args="poly.exe", stdin=poly_file)
   File "C:\Python24\lib\subprocess.py", line 533, in __init__
     (p2cread, p2cwrite,
   File "C:\Python24\lib\subprocess.py", line 607, in _get_handles
     c2pwrite = self._make_inheritable(c2pwrite)
   File "C:\Python24\lib\subprocess.py", line 634, in _make_inheritable
     DUPLICATE_SAME_ACCESS)
WindowsError: [Errno 6] The handle is invalid

So, it looks like something is wrong with the way I am redirecting 
stdin, but I have no idea what the problem is.  Any suggestions 
gratefully received

Thanks in advance

Alun Griffiths