#! /usr/bin/perl
use strict;
use warnings;

use Tie::File;

# Filename must be the script's first argument
my $filename = shift;

die "Please specify filename to be modified!\n"    if ! defined $filename;
die "'$filename' does not exist...\n"              if ! -e $filename;
die "'$filename' is a directory...\n"              if   -d _;
die "File '$filename' is not writable...\n"        if ! -w _;


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

# remove last 5 elements of @lines 
my @move = splice @lines, -5, 5;
# add removed elements in the beginning of @lines
unshift @lines, @move;

untie @lines;