How to exit a Lua script's execution?

Question

I want to exit the execution of a Lua script on some condition. For example:

content = get_content()
if not content then 
-- ( Here i want some kind of exit function )
next_content = get_content()
--example there can lot of further checks

Here I want that if I am not getting content my script suppose to terminate is should not go to check to next.

• greatwolf: os.exit() does just that.

Answer 1

Use os.exit() or just return from some "main" function if your script is embedded.

Answer 2

os.exit()

kill process by sending a signal

do return end

stop execution

The two methods are not equal if you want to write and execute some luacode in the interpreter after stopping the execution by launching your program using the -i flag.

th -i main.lua

• Kevin Bullaughey: In what way are they not equal?

Answer 3

In lua 5.2.0-beta-rc1+, you can add a label at the end of your code called ::exit:: or something of the like, and then whenever you need to exit the program just call it like this:

goto exit

• Kalib Zen: Not sure what do you mean by adding a label of ::exit:: , is that a typo ? I don't think it's a correct syntax of lua.
• Lothar: It is valid Lua syntax
• ToiletGuy: Ok, that is for the newest lua. I tried on old lua did not work

Answer 4

os.exit(ERROR_CODE) e.g. os.exit(1) is an answer.

Below is my practical example working with MS OS:

require("config_fonts")
local success, config_fonts = pcall(require, "config_fonts")
if not success then
 print("Error loading config_fonts.lua:", config_fonts)
 os.exit(1)
end

In a .bat or .cmd file:

%LUA% lua\some_script.lua
if errorlevel 1 (
 echo [ERROR] Failed to process something
 goto eof )