#!/usr/bin/perl -w
use strict;
die "Usage: save-into-arrays.pl input-file.txt\n" unless @ARGV == 1;
my @description;    # where we'll store contents of Description section
my @data;           # where we'll store contents of Data section
my %sections = ('Description:' => \@description, 'Data:' => \@data);
open(INPUT_FILE, "<$ARGV[0]") or die "Unable to open $ARGV[0]: $!\n";
my $array_ref;      # keeps reference to array currently in use
while (my $line = <INPUT_FILE>) {
  chomp $line;
  if (defined($sections{$line})) {          # is this is a section head?
    $array_ref = $sections{$line};          # yes, so point to the array for this section
  } else {
    push @$array_ref, $line if $array_ref;  # no, save this line in the active array
  }
}
close(INPUT_FILE);