file open verification

[John Howard]

Two questions - somewhat related:

Situation - I have several files on an apache server that are being
accessed by
python programs that are receiving data from html forms.

q1: How can the status of a file be checked?  If two forms have been
submitted
and the data is being added to a common file, how do I know that data
from both forms are being written correctly to the common file?

q2: Related to above - really more of a cgi question - does the apache
server keep all these file accesses separate some way?