While Zaxo's answer solves the problem.There is just on point i would like to make.
I am a big fan of perl but sometimes perl may not be the most convinient way to do something.
I feel this is one such scenario
The above file is obviously from the "*nix" world.
Since you want to modify the file, i would do so using vi rather than write a program.
vi myfile
press shift and : together
%s/\(ORA3=\)\(.*\)/\10/g.
:wq
Of course the above can be done in many other ways.
My basic point is why script when you can do this in 15 seconds in one line.
HTH