如何将Perl输出发送到STDOUT和变量？

print "Hello, World!\n";

my $output = "Hello, World!\n";
print $output;

printf "The value of pi is %.2f\n", 3.141592653589793;

my $output = sprintf "The value of pi is %.2f\n", 3.141592653589793;
print $output;

say "Hello, World!";

my $output = "Hello, World!\n";
say $output;

open(my $fh, '>', 'output.txt') or die "Can't open output.txt: $!";
select($fh);
print "Hello, File!\n";
close($fh);

open(my $fh, '>', \my $output) or die "Can't open output variable: $!";
select($fh);
print "Hello, Variable!\n";
close($fh);
print $output;