use IO::Scalar;
my ( $STD1 $STD2 );
$STD1 = new IO::Scalar \$STD2;
select $STD1;

print <<DONE;
blah blah blah
All this is being appended to the $STD2 variable
So some more text here and we are...
DONE

open FILE, ">test.txt";
print FILE $STD2;
close FILE;