How do I make an asynchronous GET request in PHP?

file_get_contents will do what you want

$output = file_get_contents('http://www.example.com/');echo $output;

Edit: One way to fire off a GET request and return immediately.

Quoted from http://petewarden.typepad.com/searchbrowser/2008/06/how-to-post-an.html

function curl_post_async($url, $params){    foreach ($params as $key => &$val) {      if (is_array($val)) $val = implode(',', $val);        $post_params[] = $key.'='.urlencode($val);    }    $post_string = implode('&', $post_params);    $parts=parse_url($url);    $fp = fsockopen($parts['host'],        isset($parts['port'])?$parts['port']:80,        $errno, $errstr, 30);    $out = "POST ".$parts['path']." HTTP/1.1\r\n";    $out.= "Host: ".$parts['host']."\r\n";    $out.= "Content-Type: application/x-www-form-urlencoded\r\n";    $out.= "Content-Length: ".strlen($post_string)."\r\n";    $out.= "Connection: Close\r\n\r\n";    if (isset($post_string)) $out.= $post_string;    fwrite($fp, $out);    fclose($fp);}

What this does is open a socket, fire off a get request, and immediately close the socket and return.

This is how to make Marquis' answer work with both POST and GET requests:

  // $type must equal 'GET' or 'POST'  function curl_request_async($url, $params, $type='POST')  {      foreach ($params as $key => &$val) {        if (is_array($val)) $val = implode(',', $val);        $post_params[] = $key.'='.urlencode($val);      }      $post_string = implode('&', $post_params);      $parts=parse_url($url);      $fp = fsockopen($parts['host'],          isset($parts['port'])?$parts['port']:80,          $errno, $errstr, 30);      // Data goes in the path for a GET request      if('GET' == $type) $parts['path'] .= '?'.$post_string;      $out = "$type ".$parts['path']." HTTP/1.1\r\n";      $out.= "Host: ".$parts['host']."\r\n";      $out.= "Content-Type: application/x-www-form-urlencoded\r\n";      $out.= "Content-Length: ".strlen($post_string)."\r\n";      $out.= "Connection: Close\r\n\r\n";      // Data goes in the request body for a POST request      if ('POST' == $type && isset($post_string)) $out.= $post_string;      fwrite($fp, $out);      fclose($fp);  }

Regarding your update, about not wanting to wait for the full page to load - I think a HTTP HEAD request is what you're looking for..

get_headers should do this - I think it only requests the headers, so will not be sent the full page content.

"PHP / Curl: HEAD Request takes a long time on some sites" describes how to do a HEAD request using PHP/Curl

If you want to trigger the request, and not hold up the script at all, there are a few ways, of varying complexities..

• Execute the HTTP request as a background process, php execute a background process - basically you would execute something like "wget -O /dev/null $carefully_escaped_url" - this will be platform specific, and you have to be really careful about escaping parameters to the command
• Executing a PHP script in the background - basically the same as the UNIX process method, but executing a PHP script rather than a shell command
• Have a "job queue", using a database (or something like beanstalkd which is likely overkill). You add a URL to the queue, and a background process or cron-job routinely checks for new jobs and performs requests on the URL