Reading files directly in Perl may be more efficient. Otherwise, here is a head demo in Perl for reading output from a binary command and wanting the first count lines. Open may be used to start a command. Note the | after $cmd. Closing the handle stops the command, likely from receiving a PIPE signal.

This is written mainly to showcase a feature of open. Scripting is lots of fun and TIMTOWTDI. Have fun orchestrating all the tools available to you.

use strict;
use warnings;

sub head {
   my ($cmd, $count) = (shift, shift || 10);
   my @output;

   open my $fh, "$cmd |" or die "error: '$cmd' failed";
   while (<$fh>) { push @output, $_; last if $. == $count; }
   close $fh;

   return @output;
}

my @foo = head('cat very_large_file', 4);

print @foo;
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