php exec and running a bash script until its finished

Question

I have a bash script that can take hours to finish.

I have a web frontend for it to make it easy to use.

On this main page, I wanna have a url that I press that starts my php command

<?exec('myscript that take a long time');?>

After the exec has finished, I want it to load a cookie.

setcookie('status',"done");

This is all easily done and works as is. However, the url that loads my exec command is a blank white page. I dont want this. I want the url to be an action which starts my phpscript and sets the cookie when the exec command returns all in the background.

Is this possible?

If not, how close can I get to this behavior.

EDIT:

function foo(){

var conn = new Ext.data.Connection();
conn.request({
url:‘request.php’,
method:‘POST’,
success: function(responseObject) {
    alert(“Hello,Word!”);
},
failure: function() {
alert(“Something fail”);
}
});}

I have tried the above code with no luck.

Firstly, why do you want to do this? If it's a thing that's being run on a regular basis, you're better off setting up a cron. Furthermore, may I suggest exec('nohup myscript that take a long time &') and afterwards setcookie() — nand
– nand, Commented Jul 5, 2013 at 18:35
That will set the cookie as soon as its done running exec not when the script is actually finished. — Cripto
– Cripto, Commented Jul 5, 2013 at 18:36
True, I missed that part. But the cookie can be voided, depending on what it's used for? Something trivial can be adding another command that "touches" some file, which you can read/check for existence. — nand
– nand, Commented Jul 5, 2013 at 18:39
So, the script that takes a really long time to run actually finishes by writing to file. How would I check (every second or so) if that file exists. I tried with php and it does it just once. — Cripto
– Cripto, Commented Jul 5, 2013 at 18:40
@nand: using (posix) nohup from a web request is NOT a good idea - it's not going to be have the way you think. — symcbean
– symcbean, Commented Jul 5, 2013 at 19:54

symcbean · Accepted Answer · 2013-07-05 21:41:24Z

I have a bash script that can take hours to finish

Stop there. That's your first problem. The WWW is not designed to maintain open requests for more than a couple of minutes. Maybe one day (since we now have websockets) but even if you know how to configure your webserver so this is not an off-switch for anyone passing by, it's exceeding unlikely that the network in between or your browser will be willing to wait this long.

Running of this job cannot be done synchronously with a web request. It must be run asynchronously.

By all means poll the status of the job from the web page (either via a meta-refresh or an ajax) but I'm having trouble understanding the benefit of setting a cookie when it has completed; usually for stuff like this I'd send out an email from the task when it completes. You also need a way to either separate out concurrent tasks invoked like this or a method of ensuring that only one runs at a time.

One solution would be to pass the PHP session id as an argument to the script, then have the script write a file named with the session id on completion - or even provide partial updates via the file - then you web page can poll the status of the job using the session id. Of course your code should check there isn't already an instance of the job running before starting a new one.

Cripto · Accepted Answer · 2013-07-07 01:47:54Z

While the other answer are correct and the WWW is not meant for open requests, we have to consider the www was never "meant" to take information.

As programmers, we made it take information such as logins.

Further more, my question was simple, how do I commit action A with result B. While sending and email would be nice and dandy as the other post by @symcbean suggests, its not a solution but a sidestep to the problem.

Web applications often need to communicate with the webserver to update their status. This is an oxymoron because the websterver is stateless. Cookies are the soultion.

Here was my solution:

$.ajax({
  url: url,
  data: data,
  success: success,
  dataType: dataType
});
setcookie('status',"done");

The url is a php function page with an if statement acting as a switch statement and running my external script that takes a really long time. This call is blocking, that is, it will not execute setcookie until it has finished.

Once it does, it will set my cookie and the rest of my web application can continue working.

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