Hi,

Running a background process in PHP

In an ideal world, all of the functions that you need would be available in the language of your choice. This is rarely the case for bioinformatics projects, where it’s often convenient or necessary to run a script or program outside your main script, grab the results and parse them. Easy enough - but if you’re writing a web application and the external program takes longer than a few seconds to run, you’re faced with a blank web page and confused users. Normally, the page loads only after all associated processes are complete.

So you’d like to run your external program in the background and display a reassuring message that says “Analysing sequence. . .”, or something similar. Here’s how you do that in PHP.

The PHP function that you need is shell_exec(). PHP has excellent online documentation: here’s the shell_exec() entry. A kind user has provided us with 2 functions for use under Linux: one for running a background process, another for monitoring a running process. I’ve edited them slightly and present them below:

function run_in_background($Command, $Priority = 0)
{
if($Priority)
$PID = shell_exec("nohup nice -n $Priority $Command 2> /dev/null & echo $!");
else
$PID = shell_exec("nohup $Command 2> /dev/null & echo $!");
return($PID);
}

function is_process_running($PID)
{
exec("ps $PID", $ProcessState);
return(count($ProcessState) >= 2);
}

Regards,
sivaraman.

Thanks for your info.
I have one question. Is there a way to find whether background process is enabled or not?.

__________________
None of us is As Strong as All of us.

Hi,

Just we know the php binary path(Ex:/home/php/bin/php), we can run the php background process.

Regards,
sivaraman.

Hi shiva,
The path /home/php/bin/php is the php installed path , it is not related with the enabling background process because it is inbuild with linux os, only we have to check shell_exec function is enabled or not , it is easily verified in the php
configuration file safe_mode_exec_dir directive

Regards,
Vivekanandan