How to check if a shell command is running from PHP

Question

EDIT: I have this but still not working; I am trying to get this to check to see if that command is running. Thanks

    function command_exist($cmd) {
    $return = shell_exec(sprintf("which %s", escapeshellarg($cmd)));
    return !empty($return);
}
if (!command_exist('rtmpdump')) {
    print 'doesnt exist';
} else {
    echo ' exists ';
}

Answer 1

On Linux/Mac

function command_exist($cmd) {
    $return = shell_exec(sprintf("which %s", escapeshellarg($cmd)));
    return !empty($return);
}
if (!command_exist('rtmpdump')) {
    print 'doesnt exist';
} else {
    shell_exec('rtmpdump');
}else {
    echo ' exists ';
}

I can suggested, you could simply use:

if (`which rtmpdump`) {
    shell_exec('rtmpdump');
}

Answer 2

   <?php 
    function command_exist($cmd) {
        $return = shell_exec(sprintf("ps -ef | grep " . escapeshellarg($cmd) . " | grep -v grep"));
        return !empty($return);
    }
    $command = 'command here';
    if (!command_exist($command)) {
        print 'not running';
    } else {
       echo ' running ';
    }
    ?>