Perl 程式碼實現：

#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;

open(LOG, '>', 'LOG_FILE') or die "Can't redirect stdout: $!";
open(CMD, 'ls |');
open(STDERR, '>&', STDOUT) or die "Can't redirect stderr: $!";
open(STDERR, '>', 'LOG_FILE') or die "Can't redirect stderr: $!";
print "LOG_FILE\n";
while (<CMD>) {
    &lprint ($_)
}

sub lprint {
      my ($line) = @_;
      print LOG $line;  
      print $line;
}

close(CMD) or die "close CMD failed: $!";

exit(1);
 

#!/usr/bin/perl

use IO::Tee; 
$tee = IO::Tee->new(">> log.txt", \*STDOUT); 
print $tee "Log on ".scalar(localtime)."\n";

#!/usr/bin/perl

open (STDOUT, "| tee -ai log.txt");
print "Log on ".scalar(localtime)."\n";
close (STDOUT);