tail -F in PHP

I'm currently writing a PHP script that pushes live log data to the front-end UI. I'm using a streaming Comet model such that my back-end would update the front-end's screen every time the log file is updated.

Unix has a nifty utility called 'tail' that can continuously monitor a file for updates and display them to standard output (which is the usually the monitor). By capturing tail's output via popen(), I was able to make a log file viewer with just a few lines:

exec("/usr/bin/killall tail");
// execute myapp in the background and redirect all of its output to logfile
exec("/usr/local/bin/myapp > /var/log/mylogfile.log 2>&1 &");

$handle = popen("/usr/bin/tail -F /var/log/mylogfile.log 2>&1", 'r');
while(1) {
   $buffer = fgets($handle);

   if (trim($buffer) == '-- ok') { // this string signifies end of execution
       pclose($handle);
       exec("/usr/bin/killall tail");
       exit();
   } else {
       echo trim($buffer);
       // if you're using Comet, push output to the stream here
   }

   ob_flush();
   flush();
}

Very cool...