Question

The code:

exec('ps aux |grep tweet',$output,$return_var);
if(count($output)>0){
    exec('php ' . DOCROOT . 'gremlins/tweet_gremlin.php &');
    file_put_contents(DOCROOT . 'gremlins/tweet_gremlin.log', date('r') . ' Tweet Gremlin was not running. Starting now...');
}

In my head, this code makes sense but it just causes the browser to loop indefinitely. What I’m trying to do is check to see if tweet_gremlin.php is running, if its not running, start it. DOCROOT is a constant defined earlier in the code.

Answer 1

You could use:

if (!exec("ps aux | grep tweet | grep -v grep")) {
    // do something
}

The grep -v part removes the grep process from the list.

Also, to execute a background process with exec and such, you will be need to redirect the output, otherwise your script will hang until the process has finished. Per example:

exec('php script.php >/dev/null &');