My suggestion is not to do it that way. If you have control over the software that creates the post, then I suggest you port it to use a database (even if it's just the file-based DBD::SQLite2). If you include an auto-incrementing ID field (and you should anyhow), then the solution is simple:

$sth = $dbh->prepare('SELECT Author, DateTime, Message, ID FROM forum_
+posts ORDER BY ID DESC');
$sth->execute();

my $records = $sth->fetchall_arrayref( undef, 50 ); #only get 50 posts

for (@$records) { RenderMessage($_) }
[download]

Of course, if you don't have control of that forum software, then you'd have to write something to read the file that's created and insert the messages into the database, first. In that case, one of the other solutions (like the File::ReadBackwards one) might be more useful.

Still, there's no good reason not to use a database for this application, so maybe upgrading is a good idea... </code>