#!/usr/bin/perl

use warnings;
use strict;

my $i = 0;

while(my $zeile = <DATA>) {

        $i = $. / 2;

        print $zeile if $i =~ m/\./;

} # while

__DATA__
Zeile1
Zeile2
Zeile3
Zeile4
Zeile5
Zeile6
Zeile7
Zeile8
Zeile9
Zeile10