Question: So I've recently setup a LEMP server and have managed to work may way through some of the configurations. I'm now to the point where I can begin writing php scripts and building basic pages. Looking at the [php5-fpm wiki](http://php-fpm.org/wiki/Main_Page) there aren't any pages discussing any changes I should expect as far as php scripts and such are concerned, only installation/configuration settings.

Is everything beyond the installation/configurations steps business as usual? From the point of view of a php developer what changes should I expect/make? How can best take advantage of the fpm version (in the php code, not module/system configurations)? I'm focused on comparing well-written php in both cases.

Answer: 
When I made the switch myself, I got to know a few perks about this kind of setup, such as APC file upload progress does not work out of the box (and you're better off using something else, such as nginx-progress-upload and/or JS File API); Some header names might have changed (prepending HTTP\_); and a new and very useful function called `fastcgi_finish_request`.

For more information, though, look around the [PHP-FPM Manual](http://php.net/manual/en/install.fpm.php).
Only major gotcha I can think of is that some functions in the `pcntl` extensions, such as `pcntl_fork`, are not supported when running under FPM. (However, they're not supported under `mod_php` either, so this shouldn't come as too much of a surprise.)