[php] Get operating system info

I recently started wondering about sites like http://thismachine.info/ that get the user's operating system info. I have not been able to find out how to do that with PHP, and wanted to try to figure it out.

I noticed that they list the user-agent, which gives lots of info about the browser. Do they get the operating system information from that, or from something else? Is there an API I could use to get the user's operating system?

I see how they got the Browser and IP, but could not figure out the Operating System part!

If you want to get all those information, you might want to read this:
http://php.net/manual/en/function.get-browser.php

You can run the sample code and you'll see how it works:

<?php
echo $_SERVER['HTTP_USER_AGENT'] . "\n\n";

$browser = get_browser(null, true);
print_r($browser);
?>

The above example will output something similar to:

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040803 Firefox/0.9.3

Array
(
    [browser_name_regex] => ^mozilla/5\.0 (windows; .; windows nt 5\.1; .*rv:.*) gecko/.* firefox/0\.9.*$
    [browser_name_pattern] => Mozilla/5.0 (Windows; ?; Windows NT 5.1; *rv:*) Gecko/* Firefox/0.9*
    [parent] => Firefox 0.9
    [platform] => WinXP
    [browser] => Firefox
    [version] => 0.9
    [majorver] => 0
    [minorver] => 9
    [cssversion] => 2
    [frames] => 1
    [iframes] => 1
    [tables] => 1
    [cookies] => 1
    [backgroundsounds] =>
    [vbscript] =>
    [javascript] => 1
    [javaapplets] => 1
    [activexcontrols] =>
    [cdf] =>
    [aol] =>
    [beta] => 1
    [win16] =>
    [crawler] =>
    [stripper] =>
    [wap] =>
    [netclr] =>
)

If you want very few info like a class in your html for common browsers for instance, you could use:

function get_browser()
{
    $browser = '';
    $ua = strtolower($_SERVER['HTTP_USER_AGENT']);
    if (preg_match('~(?:msie ?|trident.+?; ?rv: ?)(\d+)~', $ua, $matches)) $browser = 'ie ie'.$matches[1];
    elseif (preg_match('~(safari|chrome|firefox)~', $ua, $matches)) $browser = $matches[1];

    return $browser;
}

which will return 'safari' or 'firefox' or 'chrome', or 'ie ie8', 'ie ie9', 'ie ie10', 'ie ie11'.

You can look for this information in $_SERVER['HTTP_USER_AGENT'], but its format is free-form, not guaranteed to be sent, and could easily be altered by the user, whether for privacy or other reasons.

If you've not set the browsecap directive, this will return a warning. To make sure it's set, you can retrieve the value using ini_get and see if it's set.

if(ini_get("browscap")) {
    $browser = get_browser(null, true);
    $browser = get_browser($_SERVER['HTTP_USER_AGENT']);  
} 

As kba explained in his answer, your browser sends a lot of information to the server while loading a webpage. Most websites use these User-agent information to determine the visitor's operating system, browser and various information.

Based on the answer by Fred-II I wanted to share my take on the getOS function, it avoids globals, merges both lists and detects the architecture (x32/x64)

/**
 * @param $user_agent null
 * @return string
 */
function getOS($user_agent = null)
{
    if(!isset($user_agent) && isset($_SERVER['HTTP_USER_AGENT'])) {
        $user_agent = $_SERVER['HTTP_USER_AGENT'];
    }

    // https://stackoverflow.com/questions/18070154/get-operating-system-info-with-php
    $os_array = [
        'windows nt 10'                              =>  'Windows 10',
        'windows nt 6.3'                             =>  'Windows 8.1',
        'windows nt 6.2'                             =>  'Windows 8',
        'windows nt 6.1|windows nt 7.0'              =>  'Windows 7',
        'windows nt 6.0'                             =>  'Windows Vista',
        'windows nt 5.2'                             =>  'Windows Server 2003/XP x64',
        'windows nt 5.1'                             =>  'Windows XP',
        'windows xp'                                 =>  'Windows XP',
        'windows nt 5.0|windows nt5.1|windows 2000'  =>  'Windows 2000',
        'windows me'                                 =>  'Windows ME',
        'windows nt 4.0|winnt4.0'                    =>  'Windows NT',
        'windows ce'                                 =>  'Windows CE',
        'windows 98|win98'                           =>  'Windows 98',
        'windows 95|win95'                           =>  'Windows 95',
        'win16'                                      =>  'Windows 3.11',
        'mac os x 10.1[^0-9]'                        =>  'Mac OS X Puma',
        'macintosh|mac os x'                         =>  'Mac OS X',
        'mac_powerpc'                                =>  'Mac OS 9',
        'linux'                                      =>  'Linux',
        'ubuntu'                                     =>  'Linux - Ubuntu',
        'iphone'                                     =>  'iPhone',
        'ipod'                                       =>  'iPod',
        'ipad'                                       =>  'iPad',
        'android'                                    =>  'Android',
        'blackberry'                                 =>  'BlackBerry',
        'webos'                                      =>  'Mobile',

        '(media center pc).([0-9]{1,2}\.[0-9]{1,2})'=>'Windows Media Center',
        '(win)([0-9]{1,2}\.[0-9x]{1,2})'=>'Windows',
        '(win)([0-9]{2})'=>'Windows',
        '(windows)([0-9x]{2})'=>'Windows',

        // Doesn't seem like these are necessary...not totally sure though..
        //'(winnt)([0-9]{1,2}\.[0-9]{1,2}){0,1}'=>'Windows NT',
        //'(windows nt)(([0-9]{1,2}\.[0-9]{1,2}){0,1})'=>'Windows NT', // fix by bg

        'Win 9x 4.90'=>'Windows ME',
        '(windows)([0-9]{1,2}\.[0-9]{1,2})'=>'Windows',
        'win32'=>'Windows',
        '(java)([0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,2})'=>'Java',
        '(Solaris)([0-9]{1,2}\.[0-9x]{1,2}){0,1}'=>'Solaris',
        'dos x86'=>'DOS',
        'Mac OS X'=>'Mac OS X',
        'Mac_PowerPC'=>'Macintosh PowerPC',
        '(mac|Macintosh)'=>'Mac OS',
        '(sunos)([0-9]{1,2}\.[0-9]{1,2}){0,1}'=>'SunOS',
        '(beos)([0-9]{1,2}\.[0-9]{1,2}){0,1}'=>'BeOS',
        '(risc os)([0-9]{1,2}\.[0-9]{1,2})'=>'RISC OS',
        'unix'=>'Unix',
        'os/2'=>'OS/2',
        'freebsd'=>'FreeBSD',
        'openbsd'=>'OpenBSD',
        'netbsd'=>'NetBSD',
        'irix'=>'IRIX',
        'plan9'=>'Plan9',
        'osf'=>'OSF',
        'aix'=>'AIX',
        'GNU Hurd'=>'GNU Hurd',
        '(fedora)'=>'Linux - Fedora',
        '(kubuntu)'=>'Linux - Kubuntu',
        '(ubuntu)'=>'Linux - Ubuntu',
        '(debian)'=>'Linux - Debian',
        '(CentOS)'=>'Linux - CentOS',
        '(Mandriva).([0-9]{1,3}(\.[0-9]{1,3})?(\.[0-9]{1,3})?)'=>'Linux - Mandriva',
        '(SUSE).([0-9]{1,3}(\.[0-9]{1,3})?(\.[0-9]{1,3})?)'=>'Linux - SUSE',
        '(Dropline)'=>'Linux - Slackware (Dropline GNOME)',
        '(ASPLinux)'=>'Linux - ASPLinux',
        '(Red Hat)'=>'Linux - Red Hat',
        // Loads of Linux machines will be detected as unix.
        // Actually, all of the linux machines I've checked have the 'X11' in the User Agent.
        //'X11'=>'Unix',
        '(linux)'=>'Linux',
        '(amigaos)([0-9]{1,2}\.[0-9]{1,2})'=>'AmigaOS',
        'amiga-aweb'=>'AmigaOS',
        'amiga'=>'Amiga',
        'AvantGo'=>'PalmOS',
        //'(Linux)([0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}(rel\.[0-9]{1,2}){0,1}-([0-9]{1,2}) i([0-9]{1})86){1}'=>'Linux',
        //'(Linux)([0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}(rel\.[0-9]{1,2}){0,1} i([0-9]{1}86)){1}'=>'Linux',
        //'(Linux)([0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}(rel\.[0-9]{1,2}){0,1})'=>'Linux',
        '[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}'=>'Linux',
        '(webtv)/([0-9]{1,2}\.[0-9]{1,2})'=>'WebTV',
        'Dreamcast'=>'Dreamcast OS',
        'GetRight'=>'Windows',
        'go!zilla'=>'Windows',
        'gozilla'=>'Windows',
        'gulliver'=>'Windows',
        'ia archiver'=>'Windows',
        'NetPositive'=>'Windows',
        'mass downloader'=>'Windows',
        'microsoft'=>'Windows',
        'offline explorer'=>'Windows',
        'teleport'=>'Windows',
        'web downloader'=>'Windows',
        'webcapture'=>'Windows',
        'webcollage'=>'Windows',
        'webcopier'=>'Windows',
        'webstripper'=>'Windows',
        'webzip'=>'Windows',
        'wget'=>'Windows',
        'Java'=>'Unknown',
        'flashget'=>'Windows',

        // delete next line if the script show not the right OS
        //'(PHP)/([0-9]{1,2}.[0-9]{1,2})'=>'PHP',
        'MS FrontPage'=>'Windows',
        '(msproxy)/([0-9]{1,2}.[0-9]{1,2})'=>'Windows',
        '(msie)([0-9]{1,2}.[0-9]{1,2})'=>'Windows',
        'libwww-perl'=>'Unix',
        'UP.Browser'=>'Windows CE',
        'NetAnts'=>'Windows',
    ];

    // https://github.com/ahmad-sa3d/php-useragent/blob/master/core/user_agent.php
    $arch_regex = '/\b(x86_64|x86-64|Win64|WOW64|x64|ia64|amd64|ppc64|sparc64|IRIX64)\b/ix';
    $arch = preg_match($arch_regex, $user_agent) ? '64' : '32';

    foreach ($os_array as $regex => $value) {
        if (preg_match('{\b('.$regex.')\b}i', $user_agent)) {
            return $value.' x'.$arch;
        }
    }

    return 'Unknown';
}

Took the following code from php manual for get_browser.

$browser = get_browser(null, true);
print_r($browser);

The $browser array has platform information included which gives you the specific Operating System in use.

Please make sure to see the "Notes" section in that page. This might be something (thismachine.info) is using if not something already pointed in other answers.

When you go to a website, your browser sends a request to the web server including a lot of information. This information might look something like this:

GET /questions/18070154/get-operating-system-info-with-php HTTP/1.1  
Host: stackoverflow.com  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) AppleWebKit/537.36 
            (KHTML, like Gecko) Chrome/28.0.1500.95 Safari/537.36 
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: en-us,en;q=0.5  
Accept-Encoding: gzip,deflate,sdch  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7  
Keep-Alive: 300  
Connection: keep-alive  
Cookie: <cookie data removed> 
Pragma: no-cache  
Cache-Control: no-cache

These information are all used by the web server to determine how to handle the request; the preferred language and whether compression is allowed.

In PHP, all this information is stored in the $_SERVER array. To see what you're sending to a web server, create a new PHP file and print out everything from the array.

<pre><?php print_r($_SERVER); ?></pre>

This will give you a nice representation of everything that's being sent to the server, from where you can extract the desired information, e.g. $_SERVER['HTTP_USER_AGENT'] to get the operating system and browser.