Title: How does the plugin detection and activation code work?
Last modified: August 18, 2016

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# How does the plugin detection and activation code work?

 *  [olmen](https://wordpress.org/support/users/olmen/)
 * (@olmen)
 * [19 years ago](https://wordpress.org/support/topic/how-does-the-plugin-detection-and-activation-code-work/)
 * Hello fellow coders!
 * I’ve always been using WordPress for almost a year now I’ve always been very 
   impressed with the technology behind it. Most impressive imho is the plugin system.
 * I’m myself a hobby developer and I’m interested in experimenting with a similar
   modular /plugin based design. It’s quite easy to make with a database storing
   information about the modules but then you have to “install” the modules manually
   to work. What I especially like in wordpress is that it detects the new plugins
   just by browsing through the plugin folder! That’s some neat stuff.
 * Unfortunately I don’t have a clue how that’s done. I’ve been trying to look at
   wordpress’ source to figure it out but to no good.
 * Could someone who actually knows anything about this give me a little heads up?
   Like how does wordpress read through the files. And how does it read the header’s
   contents?
 * Thanks in advance 😛

Viewing 3 replies - 1 through 3 (of 3 total)

 *  [whooami](https://wordpress.org/support/users/whooami/)
 * (@whooami)
 * [19 years ago](https://wordpress.org/support/topic/how-does-the-plugin-detection-and-activation-code-work/#post-579629)
 * the simple answer to your question is found by just looking at the function, 
   get_plugins:
 *     ```
       function get_plugins() {
       	global $wp_plugins;
       if (isset ($wp_plugins)) {
       		return $wp_plugins;
       	}
   
       	$wp_plugins = array ();
       	$plugin_loc = 'wp-content/plugins';
       	$plugin_root = ABSPATH.$plugin_loc;
   
       	// Files in wp-content/plugins directory
       	$plugins_dir = @ dir($plugin_root);if ($plugins_dir) {
       while (($file = $plugins_dir->read()) !== false) {
       if (preg_match('|^\.+$|', $file))
       continue;
       if (is_dir($plugin_root.'/'.$file)) {
       $plugins_subdir = @ dir($plugin_root.'/'.$file);
       if ($plugins_subdir) {
       while (($subfile = $plugins_subdir->read()) !== false) {
       if (preg_match('|^\.+$|', $subfile))
       continue;
       if (preg_match('|\.php$|', $subfile))
       $plugin_files[] = "$file/$subfile";
       	}
       }
       } else {
       if (preg_match('|\.php$|', $file))
       $plugin_files[] = $file;
       			}
       		}
       	}
       if ( !$plugins_dir || !$plugin_files )
       		return $wp_plugins;
       foreach ( $plugin_files as $plugin_file ) {
       if ( !is_readable("$plugin_root/$plugin_file"))
       continue;
       $plugin_data = get_plugin_data("$plugin_root/$plugin_file");
   
       if ( empty ($plugin_data['Name']) )
       			continue;
       $wp_plugins[plugin_basename($plugin_file)] = $plugin_data;
       	}
       uasort($wp_plugins, create_function('$a, $b', 'return strnatcasecmp($a["Name"], $b["Name"]);'));
       return $wp_plugins;
       }
       ```
   
 * thats it, thats how it finds ’em.
 *  [whooami](https://wordpress.org/support/users/whooami/)
 * (@whooami)
 * [19 years ago](https://wordpress.org/support/topic/how-does-the-plugin-detection-and-activation-code-work/#post-579630)
 * the stuff at the top of a plugin is just parsed inside another function:
 *     ```
       function get_plugin_data($plugin_file) {
       $plugin_data = implode('', file($plugin_file));
       preg_match("|Plugin Name:(.*)|i", $plugin_data, $plugin_name);
       preg_match("|Plugin URI:(.*)|i", $plugin_data, $plugin_uri);
       preg_match("|Description:(.*)|i", $plugin_data, $description);
       preg_match("|Author:(.*)|i", $plugin_data, $author_name);
       preg_match("|Author URI:(.*)|i", $plugin_data, $author_uri);
       if (preg_match("|Version:(.*)|i", $plugin_data, $version))
       $version = trim($version[1]);
       else
       $version = '';
       $description = wptexturize(trim($description[1]));
       ....
       ```
   
 *  Thread Starter [olmen](https://wordpress.org/support/users/olmen/)
 * (@olmen)
 * [19 years ago](https://wordpress.org/support/topic/how-does-the-plugin-detection-and-activation-code-work/#post-579763)
 * Very nice! Thanks a lot! Are these among the admin-functions?

Viewing 3 replies - 1 through 3 (of 3 total)

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## Tags

 * [code](https://wordpress.org/support/topic-tag/code/)

 * In: [Developing with WordPress](https://wordpress.org/support/forum/wp-advanced/)
 * 3 replies
 * 2 participants
 * Last reply from: [olmen](https://wordpress.org/support/users/olmen/)
 * Last activity: [19 years ago](https://wordpress.org/support/topic/how-does-the-plugin-detection-and-activation-code-work/#post-579763)
 * Status: not resolved

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