Using the PHP Function Curl_Multi_Select

PHP is a powerful programming language that offers numerous functions. A function is a block of code that performs a specific task when called from within a script. These functions can take input and return output, and they can use arguments to pass information between them. Arguments are the values passed into a function when it is called, and they can be any data type.

cURL (Client URL) is a tool that allows developers to transfer data between different servers and protocols. It is often used to send and receive HTTP requests and responses, but it also supports other services such as FTP and IMAP. Using cURL, developers can rapidly and securely retrieve data from websites.

One of the most useful features of cURL is its ability to handle redirects. This is especially important in shared web hosting environments where many end users share the same resources.

To use cURL to follow redirects, you need to set up a cURL session by calling curl_init(). Once your cURL session is configured, you can call curl_exec() to download a file from the target website.

The problem with this approach is that the cURL multi handle will return before all of the requests have finished processing. In order to avoid this issue, you can call the php function curl_multi_select.

The php function curl_multi_select() adds multiple cURL multi handles to an array and executes them asynchronously. It blocks until there is activity on any of the handles and returns a cURL multi handle resource on success, or -1 on failure (from the underlying select system call). It is similar to curl_multi_exec(), but with the added benefit of asynchrony.