Creating a background task from the web

[andy_7t]

Hi,

I've got a perl script running through apache, which I want to call another program but run it in the background.

I've tried
system('/path/to/script');
system('/path/to/script &');
exec('as above');

These work, but the webpage just hangs waiting for the process to finish, or in this case, until Apache times out after 90 seconds (on my machine). How do I just fire off a background process? The background process is not a perl script by the way.

Thanks

[Corion]

merlyn wrote Watching long processes through CGI, which details all you want.

[citromatik]

...but the webpage just hangs waiting for the process to finish

You need to fork and exec for an asynchronous response of the server:

Here is some documentation that can help you:

Re: spawning Perl scripts by Abigail
Web Techniques Column 20 by merlyn


hope this helps

[jethro]

Your second example should work, to demonstrate:

perl -e ' system("emacs &"); print "hello"; '

[jasonk]

This isn't a valid comparison, though. To compare it to a web application, you would have to run it as:

perl -e 'system( "emacs &"); print "hello";'; exit

And at this point, depending on a variety of factors (whether it's a local shell or an ssh connection to another host, what shell you are using, what command you ran) the exit may work, or it may sit and wait for the background command to finish, since STDOUT and STDERR are still connected.

[jethro]

You may have a point there. But shouldn't STDOUT and STDERR be inherited from the webserver and therefore the webserver not have to wait for a close.