PHP CURL - 在抓取时存储和使用cookie的问题

I've been trying to write a script that retrieves Google trends results for a given keyword. Please note im not trying to do anything malicious I just want to be able to automate this process and run it a few times every day.

After investigating the Google trends page I discovered that the information is available using the following URL:

http://www.google.com/trends/trendsReport?hl=en-GB&q=keyword&cmpt=q&content=1

You can request that information mutliple times with no issues from a browser, but if you try with "privacy mode" after 4 or 5 requests the following is displayed:

An error has been detected You have reached your quota limit. Please try again later.

This makes me think that cookies are required. So I have written my script as follows:

$cookiefile = $siteurl . '/wp-content/plugins/' . basename(dirname(__FILE__)) . '/cookies.txt';


$url = 'http://www.google.com/trends/trendsReport?hl=en-GB&q=keyword&cmpt=q&content=1'; 
$ch = curl_init();      

curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookiefile);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookiefile);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.8) Gecko/2009032609 Firefox/3.0.8');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);        
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);


$x='error';
while (trim($x) != ''  ){
     $html=curl_exec($ch);
     $x=curl_error($ch);
}

echo  "test cookiefile contents = ".file_get_contents($cookiefile)."<br />";
echo $html;

However I just can't get anything written to my cookies file. So I keep on getting the error message. Can anyone see where I'm going wrong with this?

I'm pretty sure your cookie file should exist before you can use it with curl. Try:

$h = fopen($cookiefile, "x+");