while(<FILE>)
{
         push (@zeilen, [$_,( split /;/ )[3]]);                                 
}

for my $zeile1 (@zeilen) {
        if ( $zeile1->[1] =~ m/20/) {
                #print $zeile1->[0];
                @zweierlevel=splice(@zeilen,$_,1);
        };
};

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my @rows = map {chomp; $_} (<DATA>);
print Dumper \@rows;

my @filtered = grep { $_->[2] == 20 } map { [split /;/, $_] } @rows;
print Dumper \@filtered;

__DATA__
Zeile1;;100;;
Zeile2;;60;;
Zeile3;;20;;
Zeile4;;20;;
Zeile5;;40;;

my @first_ones;
for my $row (@rows) {
    last if [split /;/, $row]->[2] == 20;
    push @first_ones, $row;
}
print Dumper \@first_ones;

@auszug = grep { $_->[1] == 20} @zeilen;
@verkuerzt = grep { $_->[1] !=  20} @zeilen;

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my @rows = map {chomp; $_} (<DATA>);
print Dumper in_three_chunks(\@rows, 20);

sub in_three_chunks {
    my $rows = shift;
    my $criteria = shift;
    
    return unless ref $rows or not $criteria =~ /^\d+$/;
    
    my %parted = ( before => [], matching => [], after => [] );
    
    for my $row (@$rows) {
        my $cur = [split /;/, $row];
        
        push @{$parted{'matching'}}, $cur and next if $cur->[2] == $criteria;
        
        unless (@{$parted{'matching'}}) {
            push @{$parted{'before'}}, $cur;
        } else {
            push @{$parted{'after'}}, $cur;
        }
    }
    
    return \%parted;
}

__DATA__
Zeile1;;100;;
Zeile2;;60;;
Zeile3;;20;;
Zeile4;;20;;
Zeile5;;40;;