Facebook Application Token by cURL

<?php
function GetCH(){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://graph.facebook.com/oauth/access_token?client_id=YourAppId&client_secret=YOUR_APP_SECRET&grant_type=client_credentials");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
//curl_setopt($ch,CURLOPT_CONNECTTIMEOUT_MS,20000);
if(substr($url,0,8)=='https://'){
    // The following ensures SSL always works. A little detail:
    // SSL does two things at once:
    //  1. it encrypts communication
    //  2. it ensures the target party is who it claims to be.
    // In short, if the following code is allowed, CURL won't check if the
    // certificate is known and valid, however, it still encrypts communication.
    curl_setopt($ch,CURLOPT_HTTPAUTH,CURLAUTH_ANY);
    curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,false);
}
$sendCH = curl_exec($ch);
curl_close($ch);
return $sendCH;
};

$app_token = GetCH();
print_r(GetCH())
?>