#!perl
use strict;
use warnings;
my $infile = 'in.txt';
my $outfile = 'out.txt';

print 'enter a match : ';
chomp( my $match = <STDIN>);
print 'enter a replacement : ';
chomp( my $replace = <STDIN>);

open OUT,'>','regex.pl' or die "Could not create regex.pl : $!";
$match = qr(\Q$match\E);
my $regex = "s/$match/$replace/gi";
print "Regex = $regex\n";

while (<DATA>) {
    s{#REGEX#}{$regex}g;
    s{#INFILE#}{$infile}g;
    s{#OUTFILE#}{$outfile}g;
    print OUT $_;
}
close OUT;
print "Done\n";
system( 'perl regex.pl');

__DATA__
#!perl
use strict;
use warnings;
my $t0 = time();

open my $in,'<','#INFILE#' or die "Could not open #INFILE# : $!";
open my $out,'>','#OUTFILE#' or die "Could not open #OUTFILE# : $!";
my $count = 0;
while (<$in>){
  #REGEX#;
  print $out $_;
  ++$count;
}
my $dur = time() - $t0;
print "$count records processed 
#INFILE# >>  #OUTFILE#
in $dur seconds\n";