Self-terminating programs

I have a question. Is there a way to stop a program within itself, without CTRL + T? I want a program to be able to terminate itself when the user types a specific command.

try doing something like

if a == 1 then
   error()
end

This might work too

if a == 1 then
   return
end

You have to break the loop that runs the program. Depending on the way your program works and how you implement the commands there's a few ways to do it.
Some exmaples:

while true do
  -- program code --
  if <condition to stop the program> then
    break
  end
end

This way works for simple programs, wich has most of it's code in a loop. It would also work changing the break with a return.

local bExit = false
while not bExit do
  -- program code --
end

This is the one I use, it runs the program until you change the variable "bExit", wich can be changed anywhere in the program, so you can do it in the loop itself or make a function that changes it:

local function exit()
  bExit = true
end

You have several conditions to end the program this way.