#!/usr/bin/perl -w

use strict;

my $infile  = "/dir/infilename";
my $outfile = "/dir/outfilename";

open (IN,  "$infile")     or die "Error opening $infile: $!\n";
open (OUT, ">$outfile")   or die "Error opening $outfile: $!\n";

while (<IN>) {
    s/wahwah//g;          # unwanted text
    s/blahblah//g;        # more unwanted text
    s/yadayada//g;        # still more unwanted text
    s/^\s+//g;            # blank lines
    print OUT $_          or die "Error writing to $outfile: $!\n";
    }

close (IN)                or die "Error closing $infile: $!\n"; 
close (OUT)               or die "Error closing $outfile: $!\n";

# END