方法1：

$url = 'http://www.baidu.com/link?url=77I2GJqjJ4zBBpC8yDF8xDhiqDSn1JZjFWsHhEoSNd85PkV8Xil-rckpQ8_kjGKNNq';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
curl_setopt($ch, CURLOPT_NOBODY, 1);// 不需要页面内容
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);// 不直接输出
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);// 返回最后的Location
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');//有时需要这个功能
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36');
curl_setopt($ch, CURLOPT_TIMEOUT, 20);//20秒超时
curl_setopt($ch, CURLOPT_MAXREDIRS, 3);//限定只能抓取跳转3次以内的网址
curl_exec($ch);
$info = curl_getinfo($ch,CURLINFO_EFFECTIVE_URL);
curl_close($ch);
echo $info;

 方法2：

$ch=  curl_init("http://www.baidu.com");
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_AUTOREFERER, 1);
curl_setopt($ch, CURLOPT_NOBODY, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36');
curl_setopt($ch, CURLOPT_TIMEOUT, 20);//20秒超时
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');//有时需要这个功能
curl_exec($ch);
$aaa = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
curl_close($ch);
echo $aaa;

参考PHP 取 302 跳转后真实 URL 的两种方法-CSDN博客