head_tail.pl

#!/usr/bin/perl

use strict;
use warnings;

my $count = 0;

while (my $line = <STDIN>) {
    print $line;

    if (++$count >= 10) {
        last;
    }
}

if ($count >= 10) {
    open(my $tail, '| tail') or die $!;

    if (defined(my $line = <STDIN>)) {
        print "==\n";
        print $tail $line;
    }

    while (my $line = <STDIN>) {
        print $tail $line;
    }

    close($tail);
}

head_tail.py

#!/usr/bin/env python
from collections import deque
import sys

for _, L in zip(range(10), sys.stdin):
    sys.stdout.write(L)

tail = deque(sys.stdin, maxlen=10)
if tail:
    print "=="
    sys.stdout.writelines(tail)