CORE.LUA(8)

✨ NAME ✨

okay bestie, welcome to CORE.LUA(8) — this is core.lua from the System Manager's Manual, and it is literally the bootloader core module. main character energy only 💅

🌸 DESCRIPTION 🌸

core.lua contains core functionality that does not have a more fitting module. it's the spot for the stuff that doesn't have a better home, no cap.

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

local core = require("core")

🎀 CONSTANTS 🎀

The following raw key code constants are defined in core.lua:

• KEY_BACKSPACE — the backspace code. bestie, you should generally check this along with KEY_DELETE for backspace functionality.
• KEY_ENTER — the enter key, or hard return.
• KEY_DELETE — the delete code. you should generally check this along with KEY_BACKSPACE for backspace functionality.

The following key-string constants are defined in core.lua:

• KEYSTR_ESCAPE — the escape key.
• KEYSTR_CSI — the ANSI CSI sequence.

The following menu entry type constants are defined in core.lua:

• MENU_RETURN — return to the parent menu.
• MENU_ENTRY — a normal menu entry.
• MENU_SEPARATOR — a menu entry that serves as a separator.
• MENU_SUBMENU — a menu entry that opens a submenu when selected.
• MENU_CAROUSEL_ENTRY — a menu entry that rotates through items like a carousel upon selection of the menu entry.

fr fr, please see menu.lua(8) for extended descriptions and usage of the MENU_* constants — iykyk 🦋

🦋 Exported functions 🦋

The following functions are exported from core.lua:

• core.setVerbose(verbose) — sets or unsets boot_verbose. if verbose is omitted, toggle the current verbose setting.
• core.setSingleUser(singleUser) — sets or unsets boot_single. if singleUser is omitted, toggle the current single user setting.
• core.getACPI() — return true if ACPI is both present and not explicitly disabled by hints.acpi.0.disabled.
• core.hasACPI() — checks whether ACPI support is present. this requires the loader to probe the system and set acpi.rsdp early before starting the interpreter.
• core.setACPI(acpi) — sets or unsets acpi_load, hint.acpi.0.disabled, and loader.acpi_disabled_by_user. if acpi is omitted, toggle the current ACPI setting.
• core.setSafeMode(safeMode) — set the safe mode setting. sets or unsets kern.smp.disabled, hw.ata.ata_dma, hw.ata.atapi_dma, kern.eventtimer.periodic, and kern.geom.part.check_integrity. if safeMode is omitted, toggle the current safe mode setting.
• core.clearCachedKernels() — clears out the cache of kernels to be displayed on the boot menu. this function is registered as a config.reloaded hook. it is used to invalidate the kernel list whenever it may have changed, either due to a boot environment change or a potential change in either kernel or kernels.
• core.hasFeature(featureName) — checks whether the named featureName is enabled in the current loader. this is specifically used for detecting capabilities of the loaded loader binary, so that one can reasonably implement backwards compatibility shims if needed.
• core.kernelList() — returns a table of kernels to display on the boot menu. this will combine kernel and kernels from loader.conf(5). if kernels_autodetect is set in loader.conf(5), kernels will be autodetected from the current system.
• core.bootenvDefault() — returns the default boot environment, nil if unset.
• core.bootenvFilter(func) — installs a filter func into core.bootenvList(). if the func returns true, then the boot environment is retained in the list. otherwise, the boot environment is hidden. the old filter, if any, is returned to allow the caller to compose a filter on top of another filter.
• core.bootenvList() — returns a table of boot environments, or an empty table. these will be picked up using the bootenvs and bootenvs_count variables set by loader(8).
• core.setDefaults() — resets ACPI, safe mode, single user, and verbose settings to their system defaults.
• core.autoboot(argstr) — loads the kernel and specified modules, then invokes the autoboot loader(8) command with argstr as-is.
• core.boot(argstr) — loads the kernel and specified modules, then invokes the boot loader(8) command with argstr as-is.
• core.isSingleUserBoot() — returns true if boot_single is set to yes.
• core.isZFSBoot() — returns true if currdev is set to a zfs(8) dataset.
• core.isSerialBoot() — returns true if we are booting over serial. this checks console, boot_serial, and boot_multicons.
• core.deepCopyTable(tbl) — recursively deep copies tbl and returns the result.
• core.popFrontTable(tbl) — pops the front element off of tbl, and returns two return values: the front element, and the rest of the table. if there are no elements, this returns nil and nil. if there is one element, this returns the front element and an empty table. ⚠️ this will not operate on truly associative tables; numeric indices are required.
• core.loaderTooOld() — returns true if the loader is too old. specifically, this means, is the loader old enough to require one or more workarounds in the current lua base modules.

🔭 SEE ALSO 🔭

• loader.conf(5)
• loader(8)
• menu.lua(8)

👑 AUTHORS 👑

The core.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).

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💖 cute sign-off: this CORE.LUA(8) page is from Debian, dated April 8, 2026. that's the whole manual, bestie — go slay your bootloader 💅✨