Thanks for all your replies. I was able to get it implemented using sfink's /bin/tail trick:

(No, not quite. See my follow up post below.) 

#!/usr/bin/perl
use IO::Select;
use IO::Socket;
use POSIX;

local $| = 1;
$timeout = 0.1;

#### setup the file....
open $tail, "/usr/bin/tail -f -n 0 /tmp/test_file |";
my $rin = '';
vec($rin, fileno($tail), 1) = 1;
fcntl($tail, F_SETFL(), O_NONBLOCK());

###### setup the socket....
$main_sock = new IO::Socket::INET (
                LocalHost => 'localhost',
                LocalPort => 4321,
                Listen    => 5,
                Proto     => 'tcp',
                ReuseAddr => 1,
                );

$readable_handles = new IO::Select();
$readable_handles->add($main_sock);

while (1) {
    ######### do tail stuff here...
    print "selecting\n";
    $nfound = select($rout = $rin, undef, undef, $timeout);
    while ($ret = sysread $tail, $buf, 1024) {
        print $count++," $buf\n";
    }

    ######### do TCP socket stuff....
    print "checking sockets\n";
    ($new_readable) = IO::Select->select($readable_handles,
                                         undef, undef, $timeout);
    foreach $sock (@$new_readable) {
        if ($sock == $main_sock) {
            print "new connection\n";
            $new_sock = $sock->accept();
            $readable_handles->add($new_sock);
        } else {
            print "reading socket\n";
            while ($ret = sysread $sock, $buf, 1024) {
                print $count++, " $buf\n";
            }
            print "closing socket\n";
            $readable_handles->remove($sock);
            close $sock;
        }
    }
    
}

[download]

In reply to Re^2: blocking, non-blocking, and semi-blocking by genecutl
in thread blocking, non-blocking, and semi-blocking by genecutl

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.