WordPress Plugin Functions

Last updated: February 12, 2026

Core functions for plugin management, URLs, lifecycle hooks, and utilities.

Plugin Path & URL Functions

`plugin_basename( $file )`

Extracts the plugin’s relative path from its absolute file path.

// In your-plugin/your-plugin.php
$basename = plugin_basename( __FILE__ );
// Returns: 'your-plugin/your-plugin.php'

// Single-file plugin in plugins root
$basename = plugin_basename( '/var/www/html/wp-content/plugins/hello.php' );
// Returns: 'hello.php'

Parameters:

$file (string) – Absolute path to plugin file

Returns: (string) – Plugin path relative to plugins directory

Source: wp-includes/plugin.php

`plugin_dir_path( $file )`

Gets the filesystem directory path for a plugin file.

// In your-plugin/your-plugin.php
$path = plugin_dir_path( __FILE__ );
// Returns: '/var/www/html/wp-content/plugins/your-plugin/'

// Use for includes
require_once plugin_dir_path( __FILE__ ) . 'includes/class-loader.php';

Parameters:

$file (string) – Plugin’s __FILE__ constant

Returns: (string) – Directory path with trailing slash

Source: wp-includes/plugin.php

`plugin_dir_url( $file )`

Gets the URL directory path for a plugin file.

// In your-plugin/your-plugin.php
$url = plugin_dir_url( __FILE__ );
// Returns: 'https://example.com/wp-content/plugins/your-plugin/'

// Use for assets
wp_enqueue_script( 'my-script', plugin_dir_url( __FILE__ ) . 'js/script.js' );

Parameters:

$file (string) – Plugin’s __FILE__ constant

Returns: (string) – URL path with trailing slash

Source: wp-includes/plugin.php

`plugins_url( $path, $plugin )`

Retrieves a URL within the plugins or mu-plugins directory.

// Get plugins directory URL
$url = plugins_url();
// Returns: 'https://example.com/wp-content/plugins'

// Get URL to specific file
$url = plugins_url( 'js/script.js', __FILE__ );
// Returns: 'https://example.com/wp-content/plugins/your-plugin/js/script.js'

// Mu-plugin detection
// If $plugin is in WPMU_PLUGIN_DIR, returns WPMU_PLUGIN_URL

Parameters:

$path (string) – Optional. Relative path within plugin directory. Default empty.
$plugin (string) – Optional. Plugin file path. Default empty.

Returns: (string) – Plugins URL with optional path appended

Filter: plugins_url – Modify the returned URL

Source: wp-includes/link-template.php

`wp_register_plugin_realpath( $file )`

Registers a plugin’s real path for symlink resolution.

// Useful for symlinked plugin development
wp_register_plugin_realpath( __FILE__ );

Parameters:

$file (string) – Known path to the file

Returns: (bool) – Whether the path was registered

Source: wp-includes/plugin.php

Lifecycle Hook Registration

`register_activation_hook( $file, $callback )`

Sets the activation hook for a plugin.

// Function callback
register_activation_hook( __FILE__, 'my_plugin_activate' );

function my_plugin_activate() {
    // Create database tables
    // Set default options
    // Flush rewrite rules
    flush_rewrite_rules();
}

// Class method callback
register_activation_hook( __FILE__, array( 'My_Plugin', 'activate' ) );

// Object method
register_activation_hook( __FILE__, array( $this, 'activate' ) );

Parameters:

$file (string) – Plugin main file path
$callback (callable) – Function to run on activation

Action fired: activate_{$plugin} where $plugin is the plugin basename

Source: wp-includes/plugin.php

`register_deactivation_hook( $file, $callback )`

Sets the deactivation hook for a plugin.

register_deactivation_hook( __FILE__, 'my_plugin_deactivate' );

function my_plugin_deactivate() {
    // Clear scheduled events
    wp_clear_scheduled_hook( 'my_plugin_cron' );
    
    // Flush rewrite rules
    flush_rewrite_rules();
    
    // Note: Don't delete options here - that's for uninstall
}

Parameters:

$file (string) – Plugin main file path
$callback (callable) – Function to run on deactivation

Action fired: deactivate_{$plugin} where $plugin is the plugin basename

Source: wp-includes/plugin.php

`register_uninstall_hook( $file, $callback )`

Sets the uninstallation hook for a plugin.

// Must be static method or function
register_uninstall_hook( __FILE__, 'my_plugin_uninstall' );

function my_plugin_uninstall() {
    // Delete options
    delete_option( 'my_plugin_settings' );
    
    // Delete custom tables
    global $wpdb;
    $wpdb->query( "DROP TABLE IF EXISTS {$wpdb->prefix}my_plugin_data" );
    
    // Delete user meta
    delete_metadata( 'user', 0, 'my_plugin_user_data', '', true );
}

// Class static method
register_uninstall_hook( __FILE__, array( 'My_Plugin', 'uninstall' ) );

Parameters:

$file (string) – Plugin file path
$callback (callable) – Must be static method or function

Note: Alternative is uninstall.php file in plugin root.

Source: wp-includes/plugin.php

Plugin State Functions

`is_plugin_active( $plugin )`

Determines whether a plugin is active.

// Check by plugin basename
if ( is_plugin_active( 'woocommerce/woocommerce.php' ) ) {
    // WooCommerce is active
}

// Note: Only checks plugins/ directory, not mu-plugins/
// For mu-plugins, check if class/function exists instead

Parameters:

$plugin (string) – Plugin path relative to plugins directory

Returns: (bool) – True if active (site or network), false otherwise

Note: Only available after plugins_loaded. Include wp-admin/includes/plugin.php for frontend use.

Source: wp-admin/includes/plugin.php

`is_plugin_inactive( $plugin )`

Determines whether a plugin is inactive. Reverse of is_plugin_active().

if ( is_plugin_inactive( 'old-plugin/old-plugin.php' ) ) {
    // Plugin is not active
}

Source: wp-admin/includes/plugin.php

`is_plugin_active_for_network( $plugin )`

Determines whether a plugin is network-activated (Multisite only).

if ( is_plugin_active_for_network( 'my-plugin/my-plugin.php' ) ) {
    // Plugin is network-activated
}

Returns: (bool) – True if network-activated, false if single-site active or inactive

Source: wp-admin/includes/plugin.php

`is_network_only_plugin( $plugin )`

Checks for "Network: true" in the plugin header.

if ( is_network_only_plugin( 'multisite-only/multisite-only.php' ) ) {
    // Plugin requires network activation
}

Source: wp-admin/includes/plugin.php

Plugin Management Functions

`activate_plugin( $plugin, $redirect, $network_wide, $silent )`

Attempts to activate a plugin.

// Basic activation
$result = activate_plugin( 'my-plugin/my-plugin.php' );

if ( is_wp_error( $result ) ) {
    echo $result->get_error_message();
}

// Network-wide activation
activate_plugin( 'my-plugin/my-plugin.php', '', true );

// Silent activation (skip hooks)
activate_plugin( 'my-plugin/my-plugin.php', '', false, true );

Parameters:

$plugin (string) – Plugin path relative to plugins directory
$redirect (string) – Optional. URL to redirect on success. Default empty.
$network_wide (bool) – Optional. Network activation (Multisite). Default false.
$silent (bool) – Optional. Skip activation hooks. Default false.

Returns: null|WP_Error – Null on success, WP_Error on failure

Source: wp-admin/includes/plugin.php

`deactivate_plugins( $plugins, $silent, $network_wide )`

Deactivates one or more plugins.

// Single plugin
deactivate_plugins( 'my-plugin/my-plugin.php' );

// Multiple plugins
deactivate_plugins( array(
    'plugin-one/plugin-one.php',
    'plugin-two/plugin-two.php'
) );

// Silent deactivation (skip hooks)
deactivate_plugins( 'my-plugin/my-plugin.php', true );

// Network-wide deactivation
deactivate_plugins( 'my-plugin/my-plugin.php', false, true );

Parameters:

$plugins (string|string[]) – Single plugin or array of plugins
$silent (bool) – Optional. Skip deactivation hooks. Default false.
$network_wide (bool|null) – Optional. Network deactivation. Default null (both).

Source: wp-admin/includes/plugin.php

`activate_plugins( $plugins, $redirect, $network_wide, $silent )`

Activates multiple plugins.

$result = activate_plugins( array(
    'plugin-one/plugin-one.php',
    'plugin-two/plugin-two.php'
) );

if ( is_wp_error( $result ) ) {
    // Contains array of individual plugin errors
    $errors = $result->get_error_data();
}

Returns: true|WP_Error – True on success, WP_Error with plugin errors on failure

Source: wp-admin/includes/plugin.php

`delete_plugins( $plugins )`

Removes plugin files and directories.

$result = delete_plugins( array( 'old-plugin/old-plugin.php' ) );

if ( is_wp_error( $result ) ) {
    echo $result->get_error_message();
}

Parameters:

$plugins (string[]) – Array of plugin paths to delete

Returns: bool|null|WP_Error – True on success, false if empty, WP_Error on failure, null if credentials needed

Source: wp-admin/includes/plugin.php

Plugin Data Functions

`get_plugin_data( $plugin_file, $markup, $translate )`

Parses plugin file to retrieve metadata.

$data = get_plugin_data( WP_PLUGIN_DIR . '/my-plugin/my-plugin.php' );

/*
Returns:
array(
    'Name'            => 'My Plugin',
    'PluginURI'       => 'https://example.com/my-plugin',
    'Version'         => '1.0.0',
    'Description'     => 'Plugin description.',
    'Author'          => 'Author Name',
    'AuthorURI'       => 'https://example.com',
    'TextDomain'      => 'my-plugin',
    'DomainPath'      => '/languages',
    'Network'         => false,
    'RequiresWP'      => '6.0',
    'RequiresPHP'     => '7.4',
    'UpdateURI'       => '',
    'RequiresPlugins' => 'woocommerce',
    'Title'           => 'My Plugin',
    'AuthorName'      => 'Author Name',
)
*/

// Without markup (links)
$data = get_plugin_data( $file, false );

// Without translation
$data = get_plugin_data( $file, true, false );

Parameters:

$plugin_file (string) – Absolute path to main plugin file
$markup (bool) – Optional. Apply HTML markup. Default true.
$translate (bool) – Optional. Translate strings. Default true.

Returns: (array) – Plugin data array

Source: wp-admin/includes/plugin.php

`get_plugins( $plugin_folder )`

Gets all installed plugins with their data.

$all_plugins = get_plugins();

foreach ( $all_plugins as $plugin_path => $plugin_data ) {
    echo $plugin_data['Name'] . ': ' . $plugin_data['Version'];
}

// Get plugins from specific folder
$subfolder_plugins = get_plugins( '/my-folder' );

Parameters:

$plugin_folder (string) – Optional. Relative path to subfolder. Default empty.

Returns: (array[]) – Array of plugin data arrays, keyed by plugin file

Source: wp-admin/includes/plugin.php

`get_mu_plugins()`

Gets all must-use plugins.

$mu_plugins = get_mu_plugins();

foreach ( $mu_plugins as $file => $data ) {
    echo $data['Name'];
}

Returns: (array[]) – Array of mu-plugin data arrays, keyed by filename

Source: wp-admin/includes/plugin.php

`get_dropins()`

Gets all drop-in plugins.

$dropins = get_dropins();

// Check if object cache is in use
if ( isset( $dropins['object-cache.php'] ) ) {
    echo 'Object cache plugin active';
}

Returns: (array[]) – Array of drop-in data arrays, keyed by filename

Source: wp-admin/includes/plugin.php

`get_plugin_files( $plugin )`

Gets list of files belonging to a plugin.

$files = get_plugin_files( 'my-plugin/my-plugin.php' );

/*
Returns array of relative paths:
array(
    'my-plugin/my-plugin.php',
    'my-plugin/includes/class-main.php',
    'my-plugin/assets/style.css',
    ...
)
*/

Parameters:

$plugin (string) – Plugin path relative to plugins directory

Returns: (string[]) – Array of file paths relative to plugin root

Filter: plugin_files_exclusions – Directories/files to exclude from scan

Source: wp-admin/includes/plugin.php

Validation Functions

`validate_plugin( $plugin )`

Validates plugin path and header.

$result = validate_plugin( 'my-plugin/my-plugin.php' );

if ( is_wp_error( $result ) ) {
    switch ( $result->get_error_code() ) {
        case 'plugin_invalid':
            // Invalid path
            break;
        case 'plugin_not_found':
            // File doesn't exist
            break;
        case 'no_plugin_header':
            // No valid plugin header
            break;
    }
}

Returns: int|WP_Error – 0 on success, WP_Error on failure

Source: wp-admin/includes/plugin.php

`validate_plugin_requirements( $plugin )`

Validates WordPress and PHP version requirements.

$result = validate_plugin_requirements( 'my-plugin/my-plugin.php' );

if ( is_wp_error( $result ) ) {
    // Requirements not met
    echo $result->get_error_message();
}

Returns: true|WP_Error – True if requirements met, WP_Error otherwise

Error codes:

plugin_wp_php_incompatible – Both WP and PHP requirements failed
plugin_php_incompatible – PHP version too low
plugin_wp_incompatible – WordPress version too low

Source: wp-admin/includes/plugin.php

`validate_active_plugins()`

Validates all active plugins, deactivating invalid ones.

$invalid = validate_active_plugins();

foreach ( $invalid as $plugin => $error ) {
    echo $plugin . ': ' . $error->get_error_message();
}

Returns: (WP_Error[]) – Array of errors keyed by plugin file

Source: wp-admin/includes/plugin.php

Admin Menu Functions

`get_plugin_page_hook( $plugin_page, $parent_page )`

Gets the hook name for a plugin admin page.

$hook = get_plugin_page_hook( 'my-settings', 'options-general.php' );
// Returns: 'settings_page_my-settings'

Source: wp-admin/includes/plugin.php

`get_plugin_page_hookname( $plugin_page, $parent_page )`

Gets the hookname for plugin page output.

$hookname = get_plugin_page_hookname( 'my-settings', 'options-general.php' );

Source: wp-admin/includes/plugin.php

Utility Functions

`plugin_sandbox_scrape( $plugin )`

Loads a plugin in a sandbox for testing fatal errors.

// Used internally during activation
plugin_sandbox_scrape( 'my-plugin/my-plugin.php' );

Source: wp-admin/includes/plugin.php

`is_uninstallable_plugin( $plugin )`

Checks if plugin has registered an uninstall hook or has uninstall.php.

if ( is_uninstallable_plugin( 'my-plugin/my-plugin.php' ) ) {
    // Will run cleanup on deletion
}

Source: wp-admin/includes/plugin.php

`uninstall_plugin( $plugin )`

Runs the plugin’s uninstall routine.

// Called automatically during delete_plugins()
uninstall_plugin( 'my-plugin/my-plugin.php' );

Source: wp-admin/includes/plugin.php

WordPress Plugin Functions

Plugin Path & URL Functions

plugin_basename( $file )

plugin_dir_path( $file )

plugin_dir_url( $file )

plugins_url( $path, $plugin )

wp_register_plugin_realpath( $file )

Lifecycle Hook Registration

register_activation_hook( $file, $callback )

register_deactivation_hook( $file, $callback )

register_uninstall_hook( $file, $callback )

Plugin State Functions

is_plugin_active( $plugin )

is_plugin_inactive( $plugin )

is_plugin_active_for_network( $plugin )

is_network_only_plugin( $plugin )

Plugin Management Functions

activate_plugin( $plugin, $redirect, $network_wide, $silent )

deactivate_plugins( $plugins, $silent, $network_wide )

activate_plugins( $plugins, $redirect, $network_wide, $silent )

delete_plugins( $plugins )

Plugin Data Functions

get_plugin_data( $plugin_file, $markup, $translate )

get_plugins( $plugin_folder )

get_mu_plugins()

get_dropins()

get_plugin_files( $plugin )

Validation Functions

validate_plugin( $plugin )

validate_plugin_requirements( $plugin )

validate_active_plugins()

Admin Menu Functions

get_plugin_page_hook( $plugin_page, $parent_page )

get_plugin_page_hookname( $plugin_page, $parent_page )

Utility Functions

plugin_sandbox_scrape( $plugin )

is_uninstallable_plugin( $plugin )

uninstall_plugin( $plugin )

More in Plugins

WordPress Plugin-Specific Hooks

WordPress Pluggable Functions

WordPress Plugin API Overview

`plugin_basename( $file )`

`plugin_dir_path( $file )`

`plugin_dir_url( $file )`

`plugins_url( $path, $plugin )`

`wp_register_plugin_realpath( $file )`

`register_activation_hook( $file, $callback )`

`register_deactivation_hook( $file, $callback )`

`register_uninstall_hook( $file, $callback )`

`is_plugin_active( $plugin )`

`is_plugin_inactive( $plugin )`

`is_plugin_active_for_network( $plugin )`

`is_network_only_plugin( $plugin )`

`activate_plugin( $plugin, $redirect, $network_wide, $silent )`

`deactivate_plugins( $plugins, $silent, $network_wide )`

`activate_plugins( $plugins, $redirect, $network_wide, $silent )`

`delete_plugins( $plugins )`

`get_plugin_data( $plugin_file, $markup, $translate )`

`get_plugins( $plugin_folder )`

`get_mu_plugins()`

`get_dropins()`

`get_plugin_files( $plugin )`

`validate_plugin( $plugin )`

`validate_plugin_requirements( $plugin )`

`validate_active_plugins()`

`get_plugin_page_hook( $plugin_page, $parent_page )`

`get_plugin_page_hookname( $plugin_page, $parent_page )`

`plugin_sandbox_scrape( $plugin )`

`is_uninstallable_plugin( $plugin )`

`uninstall_plugin( $plugin )`