PHP/MySQL
Last Updated: 2007-02-03 14:20:23

STEP 1: About cURL

cURL stands for 'Client URL', and is perhaps the most powerful PHP extension available. cURL allows you to communicate with other servers. This may not sound like it's that interesting until you fully understand what you can do with it. For instance you can write internet crawlers that gather information for search engine results (HINT: see my search engine page). You can write merchant account gateways that validate credit card information with your bank in line with your script so there is no refreshing of the page. You can process information on FTP servers. You can gather stock information and weather information from other sites to use on your own. The possibilities are endless.

To use the cURL library you must have cURL installed as an extention to your PHP installation. If you are looking for a web host who already has cURL extentions installed, a good one that I use is fatcow.com. If you do use them be sure to list Joe Fitzgerald as your reference, because they will give me a free month of hosting if you do... and I'd appreciate that.

This tutorial assumes you've been through the first cURL tutorial that you can find here.

STEP 2: The Script

If you come across an instance where you would need to provide a remote server with a username and password when accessing files, there is a simple and easy way to do that with cURL using the curl_setopt() function with CURLOPT_USERPWD option.

<?php

// initialize your cURL session
$ch = curl_init();

// Set the URL, with the page in which you would like to access
curl_setopt($ch, CURLOPT_URL, 'http://www.amazon.com/Ronin-Frank-Miller/dp/0930289218');

// Username and password, separated by a colon.
curl_setopt($ch, CURLOPT_USERPWD, 'iang:iang');

// Execute your cURL script
curl_exec($ch);

// free up system resources taken by cURL
curl_close($ch);

?>

You can see in the above example that when using CURLOPT_USERPWD you will need to provide your username and password separated by a colon in order for this script to work.

The page from Amazon that this script is accessing does not require a username and password, but if you, for instance, had a script that was accessing bank information such as to make a credit card transaction online, you would definitely need to provide username and password credentials.