Make a copy of STDOUT and save it in the tied object. 
use Tie::Handle ();

package Tie::Handle::TimeStamp;

our @ISA = 'Tie::StdHandle';

sub wrap {
   my ($class, $globref) = @_;
   tie *$globref, $class, ">&=".fileno($globref);
}

sub WRITE {
   my $fh = $_[0];
   local ($,, $\);
   print $fh "[" . localtime() . "] " . substr($_[1], 0, $_[2]);
}

1;

[download]
use Tie::Handle::TimeStamp();

tie *STDOUT, 'Tie::Handle::TimeStamp', ">&STDOUT";
print("test\n");

# -or-

Tie::Handle::TimeStamp->wrap(\*STDOUT);
print("test\n");

[download]

Update: Changed $/ to $\.

In reply to Re: Un "tie"ing a "tie" by ikegami
in thread Un "tie"ing a "tie" by herby1620

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