Zesk Globals

Zesk globals typically contain settings and custom configurations throughout the system. They also provide a means to customize per-object behavior in an application.

The main accessor for global settings is the methods in the zesk\Configuration class which is accessible from the $application context.

$value = $application->configuration->get('named-value', $default_value); 
$application->configuration->set('named-value', $new_value);

The configuration object allows for a deep traversal tree of settings which can be organized

$_ZESK Global Storage

The global variable $_ZESK is named similarly to the PHP superglobals $_SERVER, $_REQUEST, etc. but is not a superglobal.

It is solely used for initializing the application Configuration prior to loading of Zesk's autoload.php. Once the application Configuration is instantiated, the $_ZESK global is not longer used.

Global keys are normalized to support use in a variety of contexts, but the general rule is stray punctuation is converted to underscores, and keys are lowercase. So:


... are identical. The function


Normalizes all keys before they are used to access a path into the zesk\Configuration object.

Also, the $_ZESK global structure is multi-dimensional and is accessed using a "path" with :: as the delimiter to different levels.

So, for example:

$zesk->configuration->path_set("a::b::c::d", "hello");

Would result in the global $_ZESK to have the value:

    "a" => array(
        "b" => array(
            "c" => array(
                d" => "hello"


zesk\Settings is an object which enables loading of Zesk globals from the database, and supports loading and saving those globals.

zesk\Settings::instance()->set("name", $value);

Values are serialized to the database, so complex structures can be stored and re-animated as needed. (However, use caution when storing large data as a global.)

If an application supports Settings for application configuration, all settings are loaded at Application configuration time. The Settings are loaded into the global scope, so:




Are synonymous once loaded. To save a global, do:

Settings::instance()->set("named-value", $value);

Finally, to enable zesk\Settings support in an application, simply register its hooks (TODO Is this still true?):


... prior to zesk\Application configuration.

Reserved globals

KMD: This section needs updating, and is not accurate as of 2016-08-31.


This global is set automatically by the system and can not be overwritten. It is the absolute path (including a trailing slash) to the root directory where Zesk code is stored.


This global is set automatically by the system and can not be overwritten. It is the absolute path (including a trailing slash) to the root directory where all application code is stored.


The class name of the Application. Defaults to Application. Created by Application::instance(), e.g.

class MyLittlePony extends Zesk_Application {
    // Fill in methods here
zesk::set("application_class", "MyLittlePony");
$app = Application::instance();
assert($app instanceof MyLittlePony);


Path to a directory in the local file system to store temporary files. Defaults to ZESK_APPLICATION_ROOT/cache/temp. Access via zesk::temporary_path()

$data_path = zesk::temporary_path("download-to-process");
// Returns /path/to/app/root/cache/temp/download-to-process

It is assumed that any files stored in the temporary path can be deleted after a reasonable amount of time and the application will be able to recover. To store files longer-term, store them in the data_path.


Path to a directory in the local file system to store long-term data files. Should be backed up with the application, if needed. Defaults to ZESK_APPLICATION_ROOT/data. Access via zesk::data_path()

$data_path = zesk::data_path("my_images");
// Returns /path/to/app/root/data/my_images


The directory where the web server serves all content from. This is an absolute path and is configured automatically by Zesk but can be overridden by an application if desired.


If a site is not served from a rooted web site (e.g. http://example.com/path/to/the/application/index.php) then this value is set to the prefix of the document root. It is prepended to any URL generated by the system, so in the above URL, it would be "/path/to/the/application".


Search path for shell or external commands. Similar to $PATH in bash, if not set it will use $_SERVER['PATH'] which is separated by an operating-specific separator. A semicolon-separated list of paths in the file-system.


Search path for zesk shell commands, invoked by zesk.sh. Similar to command_path, semicolon-separated. Defaults to "$ZESK_ROOT/command".


List of absolute paths (separated)


The internal PHP method to call when an assertion failed.


Set handling of assert failures.


Set handling of deprecated functionality in Zesk. Can be one of:


Linefeed character. Defaults to global defined value ZESK_DEFAULT_NEWLINE which is \n for console invocation, <br /> for web invocations. Can be set explicitly by calling newline($new_newline_characters).

Debugging Globals


Deprecated Globals


a.k.a. zesk_application_root