#!/usr/bin/perl
use strict;
use warnings;
use IO::Tee;

my $tee_file="stdout.txt";

my $tee=new IO::Tee('>&STDOUT', ">$tee_file");
close(STDOUT);
*STDOUT = $tee;

print "Test1\n";
print "Test2\n";
print "Test3\n";
print "Test4\n";