I've been tail'ing this thread with great interest! I currently monitor a log with this daemon. Notable differences from OP's environment - I'm on Unix and I rotate the log myself, monthly.

use strict;
use warnings;
use POSIX;
use IO::Handle;

my $appLog    = '/tmp/t.txt';
my $error     = 'Fatal Error';

exit            if (my $pid = fork);
defined($pid)   or die "Can't fork: $!";
POSIX:setsid()  or die "Can't setsid: $!";

$SIG{TERM} = sub {
   close LOG;
   exit;
};
$SIG{INT}  = $SIG{TERM};
$SIG{PIPE} = 'IGNORE';
$SIG{HUP}  = \&readLog;

sub readLog {
   open(LOG,"<$appLog")    or die("Unable to open $appLog: $!");
   while (<LOG>) { ;; }    # read to the end of the log
   LOG->clearerr();        # and clear EOF flag
}
&readLog;
for (;;) {
   while (<LOG>) {
      #&pageMe  if /$error/;
      print;
   }
   sleep 2;
   LOG->clearerr();   # clear EOF flag
}
[download]

This works pretty well for me. On the downside, it quietly stops working if the log is truncated or created anew. But I work around that by HUP'ing it after I rotate the log.

But hello, -F! (Who knew about it? Not my, um, man tail.) So I've tried this:

use strict;
use warnings;
use POSIX;

my $appLog    = '/tmp/t.txt';
my $error     = 'Fatal Error';

exit            if (my $pid = fork);
defined($pid)   or die "Can't fork: $!";
POSIX:setsid()  or die "Can't setsid: $!";

my $tail      = open(LOG,"/usr/local/bin/tail -F $appLog|") or die "Ca
+n't tail: $!";

$SIG{INT}     = sub {
   close LOG;
   kill 3, $tail;
   exit;
};
$SIG{TERM}    = $SIG{INT};
$SIG{PIPE}    = 'IGNORE';
$SIG{HUP}     = 'IGNORE';

while (<LOG>) {
   #&pageMe   if /$error/;
   print;
}
[download]

This seems a bit more succinct; and it gracefully handles a truncated or recreated file. A downside, perhaps, is that it creates a second process; but more importantly if I kill the daemon, the tail process doesn't receive the signal until the log is next written-to.

Any thoughts on getting my original daemon to internally handle the truncated/recreated log?

Or how the second daemon can kill the tail -F immediately?