The behaviour of these functions is affected by settings in php.ini.
| Name | Default | Changeable | Changelog | 
|---|---|---|---|
| curl.cainfo | NULL | PHP_INI_SYSTEM | Available since PHP 5.3.7. | 
Here's a short explanation of the configuration directives.
curl.cainfo
     string
    
      A default value for the CURLOPT_CAINFO option. This
      is required to be an absolute path.