dl

(PHP 4, PHP 5, PHP 7, PHP 8)

dl — Loads a PHP extension at runtime

Description

dl(string $extension_filename): bool

Loads the PHP extension given by the parameter extension_filename.

Use extension_loaded() to test whether a given extension is already available or not. This works on both built-in extensions and dynamically loaded ones (either through php.ini or dl()).

Warning

This function was removed from most SAPIs in PHP 5.3.0, and was removed from PHP-FPM in PHP 7.0.0.

Parameters

extension_filename

This parameter is only the filename of the extension to load which also depends on your platform. For example, the sockets extension (if compiled as a shared module, not the default!) would be called sockets.so on Unix platforms whereas it is called php_sockets.dll on the Windows platform.

The directory where the extension is loaded from depends on your platform:

Windows - If not explicitly set in the php.ini, the extension is loaded from C:\php5\ by default.

Unix - If not explicitly set in the php.ini, the default extension directory depends on

  • whether PHP has been built with --enable-debug or not
  • whether PHP has been built with (experimental) ZTS (Zend Thread Safety) support or not
  • the current internal ZEND_MODULE_API_NO (Zend internal module API number, which is basically the date on which a major module API change happened, e.g. 20010901)
Taking into account the above, the directory then defaults to <install-dir>/lib/php/extensions/ <debug-or-not>-<zts-or-not>-ZEND_MODULE_API_NO, e.g. /usr/local/php/lib/php/extensions/debug-non-zts-20010901 or /usr/local/php/lib/php/extensions/no-debug-zts-20010901.

Return Values

Returns true on success or false on failure. If the functionality of loading modules is not available or has been disabled (by setting enable_dl off in php.ini) an E_ERROR is emitted and execution is stopped. If dl() fails because the specified library couldn't be loaded, in addition to false an E_WARNING message is emitted.

Examples

Example #1 dl() examples

<?php
// Example loading an extension based on OS
if (!extension_loaded('sqlite')) {
    if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
        dl('php_sqlite.dll');
    } else {
        dl('sqlite.so');
    }
}

// Or using PHP_SHLIB_SUFFIX constant
if (!extension_loaded('sqlite')) {
    $prefix = (PHP_SHLIB_SUFFIX === 'dll') ? 'php_' : '';
    dl($prefix . 'sqlite.' . PHP_SHLIB_SUFFIX);
}
?>

Notes

Note:

dl() is not supported when PHP is built with ZTS support. Use the Extension Loading Directives instead.

Note:

dl() is case sensitive on Unix platforms.

See Also