my $nullpad = "\0" x (length($frompath) - length($destpath)) ;

open (FROM,"c:\perl\bin\perl.exe") ; binmode(FROM) ;
  open (TO,">c:\utils\bin\perl.exe") ; binmode(TO) ;
  while( my $line = <FROM> ) {
    $line =~ s/\Q$frompath\E(.*?)\0/$destpath$1$nullpad\0/gs ;
    print TO $line ;
  }
  close (TO) ;
close (FROM) ;