NAME

menu.lua —

FreeBSD dynamic menu boot module

DESCRIPTION

menu.lua contains the main functionality required to build a dynamic menu system. It also contains definitions for the built-in menus, some of which are influenced by loader(8) environment variables.

Before hooking into the functionality provided by menu.lua, it must be included with a statement such as the following:

local menu =
  require("menu")

MENU DEFINITIONS

Menus are represented in menu.lua as a table. That table must contain an entries key.

If the value of the entries key is itself a table, then each value in this table defines a single entry in this menu. See MENU ITEM DEFINITIONS for the structure of each entry.

entries may also be a function. This function must return a table, each value of which defines a single entry in this menu. See MENU ITEM DEFINITIONS.

MENU ITEM DEFINITIONS

The following keys may be defined for a menu item:

entry_type: The type of this menu entry. See MENU ITEM TYPES.
carousel_id: A unique string id for this carousel. A carousel is a menu entry that rotates through a selection of items. Used for storage of the carousel's current setting.
visible: A lambda that returns true if this menu item should be visible and false if it should not be visible.
items: A table (or a lambda that returns a table) of the possible choices for this carousel.
name: A string (or a lambda that returns a string) containing the current name of this item.
func: The function executed when this entry is selected. Every type except for core.MENU_SEPARATOR may have a func.
submenu: The submenu menu definition to draw when this entry is selected.
alias: A table of case-sensitive aliases for this menu entry. All menu entries that can be selected may have any number of alias entries.

entry_type is the only required key for every entry type. name is required for all entry types except for core.MENU_SEPARATOR.

MENU ITEM TYPES

The menu item type constants are defined in core.lua(8). The following types are available:

core.MENU_RETURN: Return to the parent menu. If the current menu is the default menu, menu.lua will exit the menu and begin the autoboot sequence (if applicable). This type of menu entry may execute func, when selected, and has a name.
core.MENU_ENTRY: A normal menu entry that executes func when selected, and has a name.
core.MENU_SEPARATOR: A menu entry that serves as a separator. It may have a name.
core.MENU_SUBMENU: A menu entry that opens submenu when selected. It may have a name.
core.MENU_CAROUSEL_ENTRY: A menu entry that rotates through items like a carousel. func is executed when selected, and the callback is passed the choice index, name of the current choice, and the table of choices.

EXPORTED MENUS

The following menus are exported by menu.lua:

menu.default: The default menu to draw. Set to menu.welcome by default.
menu.welcome: The welcome menu. Contains single and multi user boot options, as well as entries to access other menus.
menu.boot_options: The "Boot Options" menu.
menu.boot_environments: The "Boot Environments" menu. This menu is only visible if the system is booted on a ZFS partition and more than one boot environment was detected at boot.

EXAMPLES

To replace the default boot menu with a simple boot menu:

local core = require("core")
local menu = require("menu")

menu.default = {
	entries = {
		{
			entry_type = core.MENU_ENTRY,
			name = "Boot",
			func = core.boot,
		},
		{
			entry_type = core.MENU_CAROUSEL_ENTRY,
			carousel_id = "unique_boot_entry_name",
			items = {"NO", "YES"},
			name = function(_, choice, _)
				return "Option: " .. choice
			end,
			func = function(_, _, _)
				loader.setenv("some_envvar", "some_value")
			end,
		},
	},
}

To add another option to the welcome menu:

local core = require("core")
local menu = require("menu")

local welcome_entries = menu.welcome.all_entries
welcome_entries[#welcome_entries + 1] = {
	entry_type = core.MENU_CAROUSEL_ENTRY,
	carousel_id = "unique_boot_entry_name",
	items = {"NO", "YES"},
	name = function(_, choice, _)
		return "Option: " .. choice
	end,
	func = function(_, _, _)
		loader.setenv("some_envvar", "some_value")
	end,
}

HISTORY

The menu.lua file first appeared in FreeBSD 12.0.

AUTHORS

The menu.lua file was originally written by Pedro Souza <pedrosouza@FreeBSD.org>. Later work and this manual page was done by
Kyle Evans <kevans@FreeBSD.org>.