5.12. TUI Add-on basic features

Anaconda also supports a text-based interface (TUI). This interface is more limited in its capabilities, but on some systems it might be the only choice for an interactive installation. For more information about differences between the text-based interface and graphical interface and about limitations of the TUI, see Introduction to Anaconda and add-ons.

The text mode support in the installer is based on the simpleline library, which only allows very simple user interaction. The text mode interface:

Internally, the simpleline toolkit has three main classes: App, UIScreen and Widget. Widgets are units containing information to be printed on the screen. They are placed on UIScreens that are switched by a single instance of the App class. On top of the basic elements, hubs, spokes and dialogs all contain various widgets in a way similar to the graphical interface.

The most important classes for an add-on are NormalTUISpoke and various other classes defined in the pyanaconda.ui.tui.spokes package. All those classes are based on the TUIObject class, which itself is an equivalent of the GUIObject class. Each TUI spoke is a Python class inheriting from the NormalTUISpoke class, overriding special arguments and methods defined by the API. Because the text interface is simpler than the GUI, there are only two such arguments:

Each spoke is also expected to override several methods, namely init, initialize, refresh, apply, execute, input, prompt, and properties (ready, completed, mandatory, and status).