Tail -f live output process still running - php

Question

I am trying to do a live output of a file called fail2ban.log this log is on my linux server and i try to proccess it using. The tail process stay opened so it uses loads of cpu performance after some pepoles open the page since the process stay opened
I tried some solution of killing it with
while(true)
{
if($flag === false) die(); // Or exit if you prefer
}
The server is on Apache2
My code :
<?php
echo "Number of banned ip (live) : ";
$hand = popen("grep 'Ban' /var/log/fail2ban.log | wc -l 2>&1", 'r');
while(!feof($hand)) {
$buff = fgets($hand);
echo "$buff<br/>\n";
ob_flush();
flush();
}
pclose($hand);
echo " ";
echo "Current Log (go at the bottom of the page for the live log)";
echo " ";
$output = shell_exec('cat /var/log/fail2ban.log 2>&1');
echo "<pre>$output</pre>";
echo "Live Logs";
echo "<h1> </h1> ";
echo " ";
$handle = popen("tail -f /var/log/fail2ban.log 2>&1", 'r');
while(!feof($handle)) {
$buffer = fgets($handle);
echo "$buffer<br/>\n";
ob_flush();
flush();
}
pclose($handle);
?>
I want it to kill the process when the user quit the page.

Answer 1

No #jhnc In this case, popen is guilty, which does not end the process when the program is closed.
In general, PHP is one of the worst choices to implement tail -f. It's better to use node + websocket.
In this case, you need to check if something has been added to the file by another method. From http://php.net/manual/en/function.inotify-init.php#101093
<?php
/**
* Tail a file (UNIX only!)
* Watch a file for changes using inotify and return the changed data
*
* #param string $file - filename of the file to be watched
* #param integer $pos - actual position in the file
* #return string
*/
function tail($file,&$pos) {
// get the size of the file
if(!$pos) $pos = filesize($file);
// Open an inotify instance
$fd = inotify_init();
// Watch $file for changes.
$watch_descriptor = inotify_add_watch($fd, $file, IN_ALL_EVENTS);
// Loop forever (breaks are below)
while (true) {
// Read events (inotify_read is blocking!)
$events = inotify_read($fd);
// Loop though the events which occured
foreach ($events as $event=>$evdetails) {
// React on the event type
switch (true) {
// File was modified
case ($evdetails['mask'] & IN_MODIFY):
// Stop watching $file for changes
inotify_rm_watch($fd, $watch_descriptor);
// Close the inotify instance
fclose($fd);
// open the file
$fp = fopen($file,'r');
if (!$fp) return false;
// seek to the last EOF position
fseek($fp,$pos);
// read until EOF
while (!feof($fp)) {
$buf .= fread($fp,8192);
}
// save the new EOF to $pos
$pos = ftell($fp); // (remember: $pos is called by reference)
// close the file pointer
fclose($fp);
// return the new data and leave the function
return $buf;
// be a nice guy and program good code ;-)
break;
// File was moved or deleted
case ($evdetails['mask'] & IN_MOVE):
case ($evdetails['mask'] & IN_MOVE_SELF):
case ($evdetails['mask'] & IN_DELETE):
case ($evdetails['mask'] & IN_DELETE_SELF):
// Stop watching $file for changes
inotify_rm_watch($fd, $watch_descriptor);
// Close the inotify instance
fclose($fd);
// Return a failure
return false;
break;
}
}
}
}
// Use it like that:
$lastpos = 0;
$file = '/var/log/fail2ban.log'l
while (true) {
echo tail($file,$lastpos);
ob_flush();
flush();
}
?>
And you can't forget about max_execution_time and Apache limits