Executing the PHP/CURL command sets into action all the options defined with the curl_setopt() function. This command executes the previously configured session (referenced by $s in Example A-18).

$downloaded_page = curl_exec($s);

You can execute the same command multiple times or use curl_setopt() to change configurations between calls of curl_exec(), as long as the session is defined and hasn’t been closed. Typically, I create a new PHP/CURL session for every page I access.