There are times when your website's filesystem permissions get screwed. There's no other way to put it -- some directories are not writeable, some are not ... ARGH! The worst part is that you need to apply different permissions on files and directories, to prevent security issues.
There have been a number of times when I've realized that I must restart some service at a production server. In such enviroments, restarting a critical service ( e.g. MySQL on a webserver ) in a production enviroment is simply a no-go during hours with traffic. And since the lowest possible traffic is during morning's early hours, you can either "schedule" your service restart to occur after going out with friends for a couple of beers, be awake {until|at} that time.... or simply let your server know that something needs to be done at that time.
So you're enjoying your Webserver features, when you realize you need to change something pretty basic, such as the memory limit of PHP. That of course, is set through php.ini ... but where is that file located?