Using subprocess.Popen() in a Windows service

[Mark Shewfelt]

Hello,

I am attempting to use Popen() in a Windows service. I have a small
Win32 .exe that I normally run through the os.popen2() function. I've
written a class to work with the input and output parameters that are
passed and captured from this exe. When I use the class outside of a
service using either subprocess.Popen or os.popen2 work just fine.

When I use this class inside a Windows service it doesn't work. It
doesn't crash the service or anything but there are no values returned
from the Popen. Here's how I'm calling Popen:

p = subprocess.Popen( cmd, shell=True, bufsize=128,
stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
cwd="C:\\path_to_exe\\" )
p.wait()
(modbus_stdin, modbus_stdout)=(p.stdin,p.stdout)
lines = modbus_stdout.readlines()

While this doesn't fail there is nothing in the lines variable when it
finishes.

I am using Python 2.5 on a Windows XP Professional machine. Any help
would be greatly appreciated.

Best Regards,

Mark Shewfelt