CODEWITHSUNDEEP
phpsystemexecshell-exec
Chris81
Chris81

Reputation: 446

php shell_exec() help needed for running a script in the background

My project calls for 3 php scripts that are run with if-else conditions. The first script is loaded on the index page of the site to check if a condition is set, and if it is, it calls for the second script. The second script check to see if other conditions are set and it finally calls for the last script if everything is good.

Now I could do this by just including the scripts in the if statement, but since the final result is a resource hogging MySQL dump, i need it to be run independently of the original trigger page.

Also those scripts should continue doing their things once triggered, regardless of the user actions on the index page.

One last thing: it should be able to run on win and nix.

How would you do this?

Does the following code make any sense?

if ($blah != $blah-size){
shell_exec ('php first-script.php > /dev/null 2>/dev/null &'); 
 }
//If the size matches, die
else {
 }

Thanks a million in advance.

UPDATE: just in case someone else is going through the same deal. There seem to be a bug in php when running scripts as cgi but command line in Apache works with all the versions I've tested.

See the bug https://bugs.php.net/bug.php?id=11430

so instead i call the script like this:

exec("php-cli mybigfile.php > /dev/null 2>/dev/null &");

Or you could call it as shell. It works on nix systems but my local windows is hopeless so if anyone run it on windows and it works, please update this.

Upvotes: 2

Views: 1046

Answers (2)

Alex Howansky
Alex Howansky

Reputation: 53646

I would not do this by shell exec because you'd have no control over how many of these resource-hogging processes would be running at any one time. Thus, a user could go click-click-click-click and essentially halt your machine.

Instead, I'd build a work queue. Instead of running the dump directly, the script would submit a record to some sort of FIFO queue (could be a database table or a text file in a dir somewhere) and then immediately return. Next you'd have a cron script that runs at regular intervals and checks the queue to see if there's any work to do. If so, it picks the oldest thing, and runs it. This way, you're assured that you're only ever running one dump at a time.

Upvotes: 4

Vasil Kolev
Vasil Kolev

Reputation: 11

The easiest way I can think is that you can do

exec("screen -d -m php long-running-script.php");

and then it will return immediately and run in the background. screen will allow you to connect to it and see what's happening.

You can also do what you're doing with 'nohup php long-running-script.php', or by writing a simple C app that does daemonize() and then execs your script.

Upvotes: 1

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