subprocess: returncode v. poll()

[7stud]

Hi,

What is the difference between:

1) getting the returncode directly from the subprocess object
2) calling poll() on the subprocess object?

Here is an example:


import subprocess

p = subprocess.Popen("ls", stdout=subprocess.PIPE)
print p.returncode
print p.poll()
print

print p.stdout.read()[:5]
print

print p.returncode
print p.poll()
print p.returncode


--output:--
None
None

10tes

None
0
0