Actually, it turns out that didn't work. The file tail pipe would stop working with `ps` showing "tail [defunct]". I tried closing that pipe and then opening a new one when the sysread returned undef, but the new pipe wouldn't give me any output. I found another file tailing trick in the Perl Cookbook which now verifiably works for me. Here is the code: 
use IO::Select;
use IO::Socket;
use POSIX;

##### setup the file....
# open it
open my $tail, $FILE or die $!;

# set to non-blocking
fcntl( $tail, F_SETFL(), O_NONBLOCK() );

# [ fill up the file info buffer ]

###### setup the socket....                                           
+                                          
$main_sock;
$readable_handles;
$main_sock = new IO::Socket::INET(
    LocalHost => 'localhost',
    LocalPort => $PORT,
    Listen    => 8,
    Proto     => 'tcp',
    ReuseAddr => 1,
);
$readable_handles = new IO::Select();
$readable_handles->add($main_sock);

while (1) {

    ######### do file tail stuff here...                              
+                                           
    # unset the EOF (as seen in Perl Cookbook)
    $tail->clearerr();

    # read any new lines
    if ( @lines = (<$tail>) ) {

        # [ add @lines to buffer ]
        # [ discard old lines from buffer ]
        # [ other processing of data... ]
    }

    ######### do TCP socket stuff....                                 
+                                      
    ($new_readable) = IO::Select->select( $readable_handles, undef, un
+def, $TIMEOUT );
    foreach my $sock (@$new_readable) {
        if ( $sock == $main_sock ) {
            $new_sock = $sock->accept();
            $new_sock->autoflush(1);
            $readable_handles->add($new_sock);
        } else {
            if ( $ret = sysread $sock, $buf, 4 ) {
                # [ process the received info, generate $reply ]
                # reply to the client                                 
+                              
                print $sock $reply;
            }
            # close the client                                        
+                              
            $readable_handles->remove($sock);
            close $sock;
        }
    }
}

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In reply to Re^3: blocking, non-blocking, and semi-blocking by genecutl
in thread blocking, non-blocking, and semi-blocking by genecutl

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