There is the possibility that you're slurping the file, which doesn't scale well.

Ok... That is my script

#!/usr/bin/perl -w

use Fcntl;
use Getopt::Std;
use constant DIR => "/d/testing"; 
use constant MAX => 11;

my $prog = $0;
$prog =~ s|.*/||;

my %opts;
getopts('o:', \%opts);
my $cmd = $opts{o} || 1;

my @date = localtime(time);
my $dd = sprintf ("%02d", $date[3]);
my $mm = sprintf ("%02d", $date[4] + 1);
my $yy = sprintf ("20%02d", $date[5] % 100);
my $yymmdd = "$yy$mm$dd";

my @a;
my $bnum;
my $template = "A12 A4 A20 A20
                A2  A2 A2  A2
                A12 A4 A24 A24";

unshift (@ARGV, "-") unless @ARGV;
for my $mfile (@ARGV) {
    $file = $mfile;
    open (IN, "< $file") or die ("Can't open $file: $!\n"); 
    while (<IN>)
    {
         @normalDb = ();
         @errorDb = ();

         s/\s//g;
         $dd = $_;

         my @a = unpack($template, $dd);
         $sdate = $a[8];
         $state = $a[4];
         $err   = $a[7];

         $bnum  = substr($a[3], skip_zero($a[3]));

         substr($dd, 37, 0) = '00' if ( $state eq '02' );
         substr($dd, 62, 3) = '01' if ( $sdate !~ /^0/ && $err !~ /^0/
+ );
         substr($dd, 62, 3) = '01' if (length($dd) == 131);

         #The 2 last character of lines must be number
         if ($dd !~ /\d\d$/ || $dd =~ /<u$/ ) {
                $dd =~ s/..$/00/g;
         }

         #insert X for the rest 
         if ( length($dd) < 130 ) {
                 $dd = insert0($dd);
         } else {
                 $dd = substr($dd, 0, 130);
         }

         if ( length($dd) == 130 ) {
                 push (@normalDb, $dd);
         } else {
                 push (@errorDb, $dd);
         }

         if ( @normalDb > 0 ) {
             my $path = "$file\.ok";

             open (NORMAL, "+>> $path") or die $!;
                  for (@normalDb) { print (NORMAL "$_\n") };
             close (NORMAL);
         }

         if (@errorDb > 0 ) {
              my $path = "$file\.error";

              open(ERROR, "+>> $path") or die $!;
                   for (@errorDb) { print (ERROR "$_\n") };
              close (ERROR);
         }
    }
    close (IN);
}

sub skip_zero
{
        my ($a) = @_;
        my $j = 0;

        foreach my $i (split //, $a)
        {
                $j++;
                return $j if ($i > 0);
        }
}

sub insert0
{
        my ($tmp) = @_;
        my @data;

        push(@data, $tmp);

        for (my $i = length($tmp); $i < 130; $i++) {
                push(@data, "X");
        }

        return sprintf ("%s", join('', @data));
}

die;
[download]

As your info, the the file size is about 507156496 bytes....

...its working but not on larger files ?

Nothing stands out as particulalry wrong with your code from a quick browse--except maybe that it is probably quite slow. However, you don't say in what way it is not working on large files? Does it produce error messages? Give the wrong output? Never finish?

Are you simply not waiting long enough for it to complete?

Without some hints as to how it's failing, working out why is hard.

---

Examine what is said, not who speaks.

"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

while (<>) { # the "x" operator does the right thing for negative valu
+es
  print $_.("X" x (130-length($_)));
}
[download]