Check if a process is running using PHP in Linux

Question

I am using kannel to send SMS via PHP. I want to know how can I check if a particular process is running. For kannel to run, a process named bearerbox should be running all time. I want to check if this process is running or not. Because if the process is not running then a mail will be sent to me notifying me about it.

Monoceros

you could use a php exec function – Ertha

Make sure it's not possible for external users to modify your exec() calls, hardcode them if possible. Bad code can give evil minded people access to the whole system. – Distrain

@mattis , yeah sure I will keep that in Mind. @Ertha thanks for suggestion buddy, thats exactly what I will be using. – Monoceros

Possible duplicate of Checking if process still running? – Eleph

Answer 1

The easiest is to use pgrep, which has an exit code of 0 if the process exists, 1 otherwise.

Here's an example.

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

Saad

You may want to check, but from what I found the exit codes are the opposite way around- 1 if it exists; 0 if not. Can anyone clarify on this? – Fennell

@MattFletcher: pgrep fails (rc=1) if no process is found with that name (just tried it out). – Saad

Through shell, yes, but I just tried it out in PHP CLI and it does it the opposite way around. $output will return an array, empty or with each PID. Echoing the exec() command will return the PID or null. $return returned 0 if the process doesn't exist and 1 if it does! – Fennell

Ps: This is using PHP 5.4.9 on Ubuntu 13 – Fennell

Update: I think maybe just the timing on the commands I was running was a bit glitchy, my bad... It is the original way around described. Thought it was weird because I've seen the whole "exit code is 0 if it exists" thing in C before :) – Fennell

@MattFletcher: that's odd. I'm getting $return == 0 for existing processes, 1 otherwise (PHP 5.4.8 on RedHat). – Saad

Answer 2

You can use the exec command to find your process and then act accordingly.

Something like:

exec('ps aux | grep bearerbox', $output);

You'll need to work out what is returned on your server to decide if it's running or not.

Good luck.

Hin

Answer 3

There are a lot of ways to deal with this. The easiest (and a direct answer to your question) is to grab the output of 'ps'.

Deamons tend to always create a 'pid' file though. This file contains the process-id of the daemon. If yours has that, you can check the contents of the file and see if the process with that id is still running. This is more reliable.

supervisord might also have this functionality. Lastly, maybe it's better to get a real monitoring system rather than build something yourself. Nagios might be a good pick, but there might be others.

Sabrina

Answer 4

Simple yet handy solution to monitor processes through PHP: PHP-Linux-Process-Monitor.

The code goals like:

$ps = explode("\n", trim(shell_exec('ps axo pid,ppid,%cpu,pmem,user,group,args --sort %cpu')));
foreach($ps AS $process){
$processes[]=preg_split('@\s+@', trim($process), 7 );
}
$head= array_shift($processes);
$processes = array_reverse($processes);
$output='';
foreach ($head AS $f) $output.="<td class=\"head\">$f</td>";
$output=sprintf('<tr class="head">%s</tr>',$output);
foreach($processes AS $p){
    $output.='<tr>';
    foreach ($p AS $i=>$f){
        if($i==0) $output.=sprintf('<td>%1$s</td>',$f);
        elseif($i==2) $output.=sprintf('<td class="cpu">%1$s<ins style="width:%1$s%%"></ins></td>',$f);
        elseif($i==3) $output.=sprintf('<td class="mem">%1$s<ins style="width="%1$s%%"></ins></td>',$f);
        elseif($i == 6) $output.=sprintf('<td class="command">%1$s</td>',$f);
        else $output.=sprintf('<td>%1$s</td>',$f);
    }
    $output.='</tr>';
}
$cpu=implode('&nbsp;&nbsp;&nbsp;', sys_getloadavg());
$output=sprintf('<table data-cpu="%s" id="process">%s</table>',$cpu, $output);

Dort

Answer 5

This is the best way

<?php
exec("ps -eo comm,pid | awk '$1 == "."\"gs\""." { print $2 }'", $output);
if ($output != 0) {
    echo "The process gs is running\n";
}
?>

in the above code gs is the process that I was checking

Racy