finding sombodys Operating System with php

hi,
I am sorting out a logging system and i was wondering how you would find out sombodys operating system in php? I no how to find there ip and i have seen it where it shows the OS.

If anybody no's , thanks in advance

im still a n00b with PHP, but i'm not sure this is possible without writing out a big script. i think you might be better off using javascript for this.

You can find it in the global variable $HTTP_USER_AGENT.

This is snippet from a bigger script that id's w32-platforms:
[code]
/* Id windows32bit platform*/
$Browser_Platform = "unknown";
if(ereg( "Windows 95",$HTTP_USER_AGENT) ||
ereg( "Windows 98",$HTTP_USER_AGENT) ||
ereg( "Windows NT",$HTTP_USER_AGENT) ||
ereg( "WinNT",$HTTP_USER_AGENT) ||
ereg( "Win95",$HTTP_USER_AGENT) ||
ereg( "Win98",$HTTP_USER_AGENT))
{
$Browser_Platform = "win32";
}
[/code]