open FILE, "<datei.txt" or die "kann datei nicht oeffnen\n";
my $print = 0;
while ( my $line = <FILE> ) {
    $print = 1 if $line =~ /#vermerk[12]/;
    print $line if $print;
}
close FILE;

#!/usr/bin/perl

use strict;
use warnings;

my $file = 'test.dat';

open(my $fh,"<$file") or die $!;
while(<$fh>){
  if(/#vermerk/.../^$/){
    print unless(/#vermerk/ || /^$/);
  }
}
close $fh;