[expert] updating a file within a script

[Bob [EMAIL PROTECTED]]

Hello,

I need to have a shell script (and/or CGI) be able to modify the 
contents of an existing file (to which it has permission).  Let's say 
that somewhere in the file "test.conf", there is a line that says 
"test=on".  I would like to be able to change that one line to 
"test=off" or "test=something else".  I don't want anything else in the 
file modified - stuff before or after this line.

How do I do it?

Bob