#!/usr/local/bin/perl

open (FILE1, "$ARGV[1]") || warn "The script $0 can't open $ARGV[1]: $!\n";
open (FILE1, "$ARGV[0]") || warn "The script $0 can't open $ARGV[0]: $!\n";

while (<FILE1>){
  s/f/z/;
  s/h/y/;
  s/there/where/; 
  print $_;
}
close (FILE1);