Well, here's a generic response, though the more info as to what you're doing the better replies you can get (and the monks here can be really helpful).

You could open the file, and (if its not to big) slurp it into an array, then to some changes based on your needs then save the array to a file (possibly use tie?).

You could use File::Copy to copy the file, open in (with perl/by hand?) to do some editing.

#some code to show what I was talking about ...

$file = 'your/path/or/is\it\this\way';

# open and slurp in
open(FH,$file) or die "make a helpful die statement here";
@lines_of_file = <FH>;
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