[Tutor] How to set value back to .conf file

[hok kakada]

Hi all,

I just start to use ConfigParser to store the configuration for my 
application.
I surfed the mails related to ConfigParser, however I couldn't found the way 
of how to set value back to the .conf file.

Let say, I have a test.conf file with:
[General]
userName="da"

later on, I wanna add another option:
email="da at aa.info"

I did the following:
import ConfigParser
conf = ConfigParser.ConfigParser()
conf.read('test.conf')

conf.set('General', 'email', 'da at aa.info'

print conf.items('General')
[('username','da'),('email','da at aa.info')]

But when I look into the file test.conf directly, I didn't see the option 
'email' . I don't know what I am missing here?

Or i need to write it to the file using conf.write(fp)?
If so, how can I get this file pointer?

Thanks very much for your input.

da
-- 
Ms.Kakada Hok
Open Source Engineer
KhmerOS project
Open Institute Organization
H/P:(+855-12) 653 155