If you want to go to /buy
after you log in, just use the same curl handle and issue another request for that page. cURL will retain the cookies for the duration of the handle (and on subsequent requests since you are saving them to a file and reading them back with the cookie jar.
For example:
$user_agent = "Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20140319 Firefox/24.0 Iceweasel/24.4.0";
$curl_crack = curl_init();
CURL_SETOPT($curl_crack,CURLOPT_URL,"https://www.vininspect.com/en/account/login");
CURL_SETOPT($curl_crack,CURLOPT_USERAGENT,$user_agent);
CURL_SETOPT($curl_crack,CURLOPT_PROXY,"183.78.169.60:37899");
CURL_SETOPT($curl_crack,CURLOPT_PROXYTYPE,CURLPROXY_SOCKS5);
CURL_SETOPT($curl_crack,CURLOPT_POST,True);
CURL_SETOPT($curl_crack,CURLOPT_POSTFIELDS,"LoginForm[email]=naceriwalid%40hotmail.com&LoginForm[password]=passwordhere&toploginform[rememberme]=0&yt1=&toploginform[rememberme]=0");
CURL_SETOPT($curl_crack,CURLOPT_RETURNTRANSFER,True);
CURL_SETOPT($curl_crack,CURLOPT_FOLLOWLOCATION,True);
CURL_SETOPT($curl_crack,CURLOPT_COOKIEFILE,"cookie.txt"); //Put the full path of the cookie file if you want it to write on it
CURL_SETOPT($curl_crack,CURLOPT_COOKIEJAR,"cookie.txt"); //Put the full path of the cookie file if you want it to write on it
CURL_SETOPT($curl_crack,CURLOPT_CONNECTTIMEOUT,30);
CURL_SETOPT($curl_crack,CURLOPT_TIMEOUT,30);
$exec = curl_exec($curl_crack);
if(preg_match("/^you are logged|logout|successfully logged$/i",$exec))
{
$post = array('search' => 'keyword', 'abc' => 'xyz');
curl_setopt($curl_crack, CURLOPT_POST, 1); // change back to GET
curl_setopt($curl_crack, CURLOPT_POSTFIELDS, http_build_query($post)); // set post data
curl_setopt($curl_crack, CURLOPT_URL, 'http://example.com/buy'); // set url for next request
$exec = curl_exec($curl_crack); // make request to buy on the same handle with the current login session
}
Here are some other examples of using PHP & cURL to make multiple requests:
How to login in with Curl and SSL and cookies (links to multiple other examples)
Grabbing data from a website with cURL after logging in?
Pinterest login with PHP and cURL not working
Login to Google with PHP and Curl, Cookie turned off?
PHP Curl - Cookies problem