use strict;
use warnings;
use open qw(:std :utf8); # Set the default encoding for STDIN, STDOUT & STDERR to UTF-8 
use IO::Tee ();

my $logname = 'test-tee$.log';
open(my $logfile, ">:encoding(UTF-8)", $logname) or die qq(Can't open "$logname for writing"\n);
# Tee STDERR to log file. If running as Administrator, console window may disappear quickly!
open STDERR2, ">&=STDERR" or die "Failed to alias STDERR: $!";
*STDERR = IO::Tee->new(\*STDERR2, ">$logfile") or 
  die "Failed to tee to aliased STDERR and '$logfile': $!";

print(STDERR "This is a test\n");