On Redhat-ish linux, you must install both libtidy and libtidy-devel (PHP 5.x):
sudo yum install libtidy libtidy-devel
This extension is bundled with PHP 5 and greater, and is installed using the --with-tidy configure option.
On Redhat-ish linux, you must install both libtidy and libtidy-devel (PHP 5.x):
sudo yum install libtidy libtidy-devel