Checking if process still running?

Question

As a way to build a poor-man\'s watchdog and make sure an application is restarted in case it crashes (until I figure out why), I need to write a PHP CLI script that will be

Answer 1

<?php

function check_if_process_is_running($process)
{
    exec("/bin/pidof $process",$response);
    if ($response)
    {
         return true;
    } else
    {
         return false;
    }
}

if (check_if_process_is_running("mysqld"))
{
      echo "MySQL is running";
} else
{
      echo "Mysql stopped";
}

?>

Answer 2

To check whether process is running by its name, you can use pgrep, e.g.

$is_running = shell_exec("pgrep -f lighttpd");

or:

exec("pgrep lighttpd", $output, $return);
if ($return == 0) {
    echo "Ok, process is running\n";
}

as per this post.

If you know the PID of the process, you can use one the following functions:

  /**
   * Checks whether the process is running.
   *
   * @param int $pid Process PID.
   * @return bool
   */
  public static function isProcessRunning($pid) {
    // Calling with 0 kill signal will return true if process is running.
    return posix_kill((int) $pid, 0);
  }

  /**
   * Get the command of the process.
   * For example apache2 in case that's the Apache process.
   *
   * @param int $pid Process PID.
   * @return string
   */
  public static function getProcessCommand($pid) {
    $pid = (int) $pid;
    return trim(shell_exec("ps o comm= $pid"));
  }

Related: How to check whether specified PID is currently running without invoking ps from PHP?

Answer 3

i have a function to get the pid of a process...

function getRunningPid($processName) {
    $pid = 0;
    $processes = array();
    $command = 'ps ax | grep '.$processName;
    exec($command, $processes);
    foreach ($processes as $processString) {
        $processArr = explode(' ', trim($processString));
            if (
            (intval($processArr[0]) != getmypid())&&
            (strpos($processString, 'grep '.$processName) === false)
        ) {
            $pid = intval($processArr[0]);
        }
    }
    return $pid;
}