#!/usr/bin/perl
use warnings;
use strict;
my $string="Hello";

{
   local @ARGV = ("$ARGV[0]");
   local $^I = '.bac';
   while(<>){
      if ($. == 1) {            # if line no is 1
         print "$string$/";   
         print;                 # Also print the current line
      }
      else {
         print;
      }
   }
}