use strict;
use warnings;

open my $inFH, q{<}, \ <<__EOD__ or die $!;
<t id=2bc>Only the...</t>
<t id=1>Only the...</t>
<t id=12>Only the...</t>
<t id=21>Only the...</t>
<t id=1>Only the...</t>
<t id=1a>Only the...</t>
<t id=2>Only the...</t>
<t id=2>Only the...</t>
<t id=2>Only the...</t>
<t id=2>Only the...</t>
<t id=3>Only the...</t>
<t id=17d>Only the...</t>
<t id=35>Only the...</t>
<t id=31>Only the...</t>
<t id=2b>Only the...</t>
<t id=4>Only the...</t>
<t id=42>Only the...</t>
<t id=5>Only the...</t>
<t id=51>Only the...</t>
<t id=2ac>Only the...</t>
<t id=52>Only the...</t>
<t id=6>Only the...</t>
<t id=7>Only the...</t>
__EOD__

print for
   map { unpack q{x13a*}, $_ }
   sort
   map { m{(?x) (?<=id=) ( \d+ ) ( [a-z]* ) (?=>)}
         &&
         pack q{cNa8a*}, ( length $2 ? 1 : 0 ), $1, $2, $_
       }
   <$inFH>;

close $inFH or die $!;

##</code><code>##

<t id=1>Only the...</t>
<t id=1>Only the...</t>
<t id=2>Only the...</t>
<t id=2>Only the...</t>
<t id=2>Only the...</t>
<t id=2>Only the...</t>
<t id=3>Only the...</t>
<t id=4>Only the...</t>
<t id=5>Only the...</t>
<t id=6>Only the...</t>
<t id=7>Only the...</t>
<t id=12>Only the...</t>
<t id=21>Only the...</t>
<t id=31>Only the...</t>
<t id=35>Only the...</t>
<t id=42>Only the...</t>
<t id=51>Only the...</t>
<t id=52>Only the...</t>
<t id=1a>Only the...</t>
<t id=2ac>Only the...</t>
<t id=2b>Only the...</t>
<t id=2bc>Only the...</t>
<t id=17d>Only the...</t>