#!/usr/bin/perl -w
use strict;
use Archive::Tar;

my $filename = "filename.tar.gz";
my $tar = Archive::Tar->new($filename);
my @filenames = $tar->list_files;
$tar->extract_file($filenames[0],'temp.out');
open(DATA, "temp.out");
while (<DATA>) {
...
}
close(DATA);