#/usr/bin/perl
use strct;
use warnings;

my $shared=100; # 100 Zeichen Überschneidung
my $chuncksize=10*1024*1024;
my $file='C:\myfile.txt';
my $regexp=qx/CP_NG/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 += $chunk =~ m/$regexp/g;
  $old=substr($chunk,-$shared,$shared);
  $old =~ s/$regexp//g;
}
print "anzahl treffer: $found\n";