To enable InterBase support configure PHP --with-interbase[=DIR] , where DIR is the InterBase base install directory, which defaults to /usr/interbase.
Note: Note to Win32 Users
为了使此扩展生效， DLL 文件必须能在 Windows 系统的 PATH 指示的路径下找到。如何操作的信息，请参见题为“如何在 Windows 中将 PHP 目录加到 PATH 中”的FAQ。虽然将 DLL 文件从 PHP 文件夹复制到 Windows 系统目录也行，但不建议这样做。 此扩展需要下列文件在 PATH 路径中： gds32.dll
In case you installed the InterBase database server on the same machine PHP is running on, you will have this DLL already. Therefore you don't need to worry because gds32.dll will already be in the PATH.