To enable the PHP-cURL extension on Linux Ubuntu/Debian, you must first install it with the command:
sudo apt-get install php-curl
Or so for the old PHP5 version:
sudo apt-get install php5-curl
You can activate/deactivate the PHP module like this:
sudo phpenmod curl
sudo phpdismod curl
Restart Apache2 to apply the changes:
sudo /etc/init.d/apache2 restart
Let’s see if curl is activated:
php -i | grep -i curl
On Windows systems, cURL is usually bundled with PHP, and to enable it, you need to uncomment the extension=php_curl.dll line in the php.ini file. Then restart the Apache2 service.
See also my article:
How to compile cURL on Ubuntu