WordPress at a glance
action is not described

activated_plugin action-hook . WP 2.9.0

Fires after a plugin has been activated.

If a plugin is silently activated (such as during an update), this hook does not fire.

Usage

add_action( 'activated_plugin', 'action_function_name_5539', 10, 2 );
function action_function_name_5539( $plugin, $network_wide ){
	// action...
}
$plugin(string)
Path to the main plugin file from plugins directory.
$network_wide(true/false)
Whether to enable the plugin for all sites in the network or just the current site. Multisite only.
Default: false

Where the hook is called

activate_plugin()
wp-admin/includes/plugin.php 625
do_action( 'activated_plugin', $plugin, $network_wide );

Where the hook is used (in WP core)

Does not used.