sub get_n_lines {
    local *FH = shift;
    my $n  = shift;
    my @lines;
    for (1..$n) {
        my $line = <FH>;
        push @lines, $line if defined $line;
    } 
  return @lines;
}

while (my @lines = get_n_lines(*DATA, 5)) {
    print "Got:\n", @lines , "\n";
}


__DATA__
line 1
line 2
line 3
line 4
line 5
line 6
line 7
line 8
line 9
line 10
line 11
line 12
line 13
line 14
line 15
line 16
line 17
line 18