head + tail command

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, '|-', qw/tail/) or die $!;

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

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

    close($tail);
}