Exported Variables

The following variables are provided by the Lua interpreter in the loader table:

machine

The target's hw.machine sysctl(8) value.

machine_arch

The target's hw.machine_arch sysctl(8) value. Some boot loaders are 32-bit applications that then load a 64-bit kernel. In these cases, machine_arch represents the 32-bit architecture, not the 64-bit architecture.

lua_path

The current lua loading path.

version

The version of the boot program.

Exported Functions

The following functions are exported in the loader table.

delay(usec)

Delay for usec microseconds.

command_error()

Returns the error string from the last command to fail.

command(argc, argv)

Like perform() but the arguments are already parsed onto the stack.

exit(status)

Exit the boot loader back to the firmware with a status of status. The interpretation of this value is firmware specific.

interpret(str)

Execute the loader builtin command str as if it were typed by the user. This will first try to execute str as Lua. If that fails, it will attempt to execute it as a cli command, including those defined by the cli.lua(8) mechanism. If that fails, it will attempt to execute it as a builtin command and return the same values as perform().

parse(str)

Parses the command str into its words and return those words on the stack.

getenv(name)

Obtains the value of the environment variable name.

has_command(cmd)

returns true if commmand is present in the interpreter as a builtin. Otherwise it returns nil and an error string. It does not check the “cli” table to see if a user defined command has been created.

has_feature(feature)

returns true if the feature is enabled. Otherwise it returns nil and an error string.

perform(str)

Execute the loader builtin command str. Returns the result of the command, one of the following values:

loader.CMD_OK

The command completed successfully.

loader.CMD_WARN

The command was successful, but the user stopped its output prematurely.

loader.CMD_ERROR

The command did not complete successfully. Use command_error to retrieve the error.

loader.CMD_CRIT

The command returned a critical error that was already printed.

loader.CMD_FATAL

The command determined continuation was not possible and the loader panicked. In practice, though, panic() does not return.

printc(str)

Outputs the string using the loader's putchar() function. This function is also available globally as printc().

setenv(name, value)

Insert or reset the environment variable name into the loader's environment list. If no environment variable with this name exists, one is created. If one exists, its value is replaced.

time()

Returns the loader's notion of time, in seconds since 1970. The value of loader's notion varies somewhat between different loading environments.

unsetenv(name)

Removes the environment variable name from the loader's environment list.

Compatibility

The functions fb_bezier(), fb_drawrect(), fb_line(), fb_putimage(), fb_set_pixel(), term_drawrect(), and term_putimage() have moved to the gfx table. They remain in the loader table for a transition period and are documented in gfx.lua(8).

Default File

In addition, the Lua interpreters start with the file /boot/lua/loader.lua when they start to boot the system. The default one will fixup the screen, load the configuration files, check for a password, and then load the menu or load the kernel file and then return. If autoboot is enabled, the loaded files will boot.