#!/usr/bin/perl
use strict;
use warnings;

my $shared=100; # 100 Zeichen Überschneidung
my $chuncksize=10*1024*1024;

my $file='test.random.txt';
my $regexp=qr/--TEST--/o;

open(TRACEFILE, '<',  $file ) or die "cannot open $file $!\n";

my $found=0;
my $chunk;
my $old="";

while (read(TRACEFILE, $chunk, $chuncksize))
{
  $chunk=$old.$chunk;
  $found++ while($chunk =~ m/$regexp/gsc);
  $old = substr($chunk,-$shared,$shared);
  $old =~ s/$regexp//gs;
}

print "anzahl treffer: $found\n";