is_network_only_plugin() │ WP 3.0.0

Checks for "Network: true" in the plugin header to see if this should be activated only as a network wide plugin. The plugin would also work when Multisite is not enabled.

Checks for "Site Wide Only: true" for backward compatibility.

No Hooks.

Returns

bool. True if plugin is network only, false otherwise.

Usage

is_network_only_plugin( $plugin );
$plugin(string) (required)
Path to the plugin file. Accepts a path relative to the plugins directory, or an absolute path, with or without surrounding whitespace.

Changelog

Since 3.0.0 Introduced.
Since 7.1.1 The $plugin path is normalized with plugin_basename() trim(), matching how activate_plugin() it.

is_network_only_plugin() code WP 7.1.2

wp-admin/includes/plugin.php 
function is_network_only_plugin( $plugin ) {
	// Normalize the path the same way activate_plugin() does, so both agree on the file.
	$plugin = plugin_basename( trim( $plugin ) );

	$plugin_data = get_plugin_data( WP_PLUGIN_DIR . '/' . $plugin );
	if ( $plugin_data ) {
		return $plugin_data['Network'];
	}
	return false;
}