#!C:\Perl\bin\perl.exe -w

# Benötigte Variablen
my $dep_arc_file = "C:\\Perl\\scripts\\test.csv";
my $dia_ert_file = "C:\\Perl\\scripts\\D925007";
my @arc = ();
my @ert = ();

open(ARC, $dep_arc_file ) || die "Can not open file $dep_arc_file\n";
while (<ARC>) 
{
        # Spaltenueberschrift ignorieren
        if (! /^Zeilenueberschrift/) 
        {
                chomp;
                push (@arc, $_);
        }
}
close(ARC);

open(DIA, $dia_ert_file) || die "Can not open file $dia_ert_file\n";
while (<DIA>)
{
        chomp;
        push (@ert, $_);
}
close(DIA);

foreach my $line (@ert)
{
        my $found = 0;
        my $rest = 1;
        if ( $line =~ /^xxx(\d{8})/ )
        {
                foreach my $tmp (@arc)
                {
                        if ($tmp eq $1)
                        {
                                $found = 1;
                                $rest = 2;
                        }
                }
        }
        if (( $found ne 1 ) && ( $rest eq 1 ))
        {
                print $line."\n";
        }
}

#!/opt/local/bin/perl5.10.0
use 5.010;
use strict;
use warnings;

use constant {
  EXCLUDE_TXT => '2.txt',
  DATA_TXT => '1.txt'
};

my %exclude = do {
  open my $in, '<', EXCLUDE_TXT or die "Cannot open exclusion list: $!";
  my $_; map { chomp; $_ => 1 } <$in>;
};

do {
  open my $in, '<', DATA_TXT or die "Cannot open data file: $!";
  while (my $_ = <$in>) {
    my $flop;
    print if (
      (/^xxx(\d{8})/ && !$exclude{$1})
      ...
      ($flop = (/^xxx(\d{8})/ && $exclude{$1}))
      and !$flop
    );
  }
}