#!/usr/bin/perl
use strict;#dont let me do silly things
use warnings;#tell me if I try to do them anyway
use autodie;#halt and catch fire if things dont work out
my $keyword = qr/what/;#store the regex
open(my $fh,'<','input_file');#open input file for reading using $fh filehandle
open(my $outf,'>','output_file');#open output file for writing
while(<$fh>){
     if($_ =~ $keyword){#if the line matches te keyword then
        next;#jump to next line
     }
     print $outf $_;#print current line to the output file
}
close $fh;#cleanly close the input file
close $outf;#cleanly close the output file