#! perl
use strict;
use warnings;
use Tie::File;

my $file = 'test.txt';

tie my @lines, 'Tie::File', $file or die "Cannot tie file '$file': $!";

for my $i (0 .. $#lines)
{
    if ($lines[$i] =~ m{ \b jack \b }x)
    {
        for ($i - 2 .. $i)
        {
            print $lines[$_], "\n" unless $_ < 0;
        }

        for (my $found = 0; !$found && $i <= $#lines; ++$i)
        {
            if ($lines[$i] =~ m{ \b lastname \b }x)
            {
                print $lines[$i], "\n";
                $found = 1;
            }
        }
    }
}

untie @lines;