#!/usr/bin/perl

use strict;
use warnings;
my($copy) = "$ARGV[0].bak";
copy($ARGV[0], $copy) or die "File cannot be copied. \n";

open(INPUT,"$copy") or die 'Cannot open file: $!\n';
open(OUTPUT,">$ARGV[0]");

my($replacePattern1) = "foo1";
my($searchPattern1) = "bar1";
my($replacePattern2) = "foo2";
my($searchPattern2) = "bar2";
my($replacePattern3) = "foo3";
my($searchPattern3) = "bar3";
my($pattern) = 0;

while (<INPUT>) {
   if ($_ =~ s/$searchPattern1/$replacePattern1/g) {
   $pattern = 1;
   }
   elsif ($_ =~ s/$searchPattern2/$replacePattern2/g) {
   $pattern = 2;
   }
   elsif ($_ =~ s/$searchPattern3/$replacePattern3/g) {
   $pattern = 3;
   }
   print OUTPUT $_;
}close INPUT;
close OUTPUT;
unlink($copy);