See here for more details:
http://www.html-form-guide.com/php-form/php-form-submit.html
eg:
<?php
$url = 'http://localhost/curl/1.php';
$params = "keyword=123&zxczxc=333";
$user_agent = "Mozilla/5.0 (compatible; MSIE 5.01; Windows NT 5.0)";
$ch = curl_init();
curl_setopt($ch, CURLOPT_POST,1);
curl_setopt($ch, CURLOPT_POSTFIELDS,$params);
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_USERAGENT, $user_agent);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
$result=curl_exec ($ch);
curl_close ($ch);
echo "Results: <br>".$result;
?>
1.php content:
<?
print_r($_POST);
?>
Questions Related to SO:
https://stackoverflow.com/search?q=php+form+curl
Publish a text area using cURL
Using PHP and curl to publish html form containing file
php cURL, fill out the remote form
Other articles:
http://www.askapache.com/htaccess/sending-post-form-data-with-php-curl.html
http://davidwalsh.name/execute-http-post-php-curl
http://curl.haxx.se/mail/curlphp-2004-04/0013.html
http://phpsense.com/php/submitting-forms-using-php-curl.html
http://www.maheshchari.com/submit-a-form-to-remote-server-with-php-curl/