Функция для получения размера терминала. Я использую её для создания cli-ui

ffi-terminal-size.lua

local ffi = require("ffi")
local terminalSize

if package.config:sub(1, 1) == "\\" then -- windows
	local kernel32 = ffi.load("kernel32")
	ffi.cdef([[
	typedef struct _CONSOLE_SCREEN_BUFFER_INFO {
		uint16_t dwSizeX;
		uint16_t dwSizeY;
		uint16_t dwCursorPositionX;
		uint16_t dwCursorPositionY;
		uint16_t wAttributes;
		uint16_t srWindowLeft;
		uint16_t srWindowTop;
		uint16_t srWindowRight;
		uint16_t srWindowBottom;
		uint16_t dwMaximumWindowSizeX;
		uint16_t dwMaximumWindowSizeY;
	} CONSOLE_SCREEN_BUFFER_INFO;

	bool GetConsoleScreenBufferInfo(void* hConsoleOutput, CONSOLE_SCREEN_BUFFER_INFO* lpConsoleScreenBufferInfo);
	void* GetStdHandle(uint32_t nStdHandle);
	]])

	local STD_OUTPUT_HANDLE = -11
	local hConsole = kernel32.GetStdHandle(STD_OUTPUT_HANDLE)
	local csbi = ffi.new("CONSOLE_SCREEN_BUFFER_INFO")

	function terminalSize()
		if kernel32.GetConsoleScreenBufferInfo(hConsole, csbi) then
			return csbi.dwSizeX, csbi.dwSizeY
		end

		return 80, 24 -- fallback
	end
else -- linux
	ffi.cdef([[
	typedef struct {
		unsigned short ws_row;
		unsigned short ws_col;
		unsigned short ws_xpixel;
		unsigned short ws_ypixel;
	} winsize;

	int ioctl(int fd, unsigned long request, ...);
	]])

	local TIOCGWINSZ = 0x5413

	function terminalSize()
		local ws = ffi.new("winsize")
		ffi.C.ioctl(0, TIOCGWINSZ, ws)
		return ws.ws_col, ws.ws_row
	end
end

local lib = setmetatable({
	test = function()
		local w, h = terminalSize()
		print("terminal size: ".. w ..", ".. h)

		local sleep = require("timer").sleep
		local delay = 2 / h * 1000

		local base = "progress [%s] ETA: null | %s/".. h
		local max_wide = w - #base - 4 - 3

		for y = 1, h do
			local wide = math.floor(y / h * max_wide)

			print(base:format(string.rep("=", wide) .. string.rep("-", max_wide - wide), y))
			sleep(delay)
		end
	end
}, {__call = terminalSize})

-- lib.test()
return lib