terminating a game of battleship

i am writting the gaem battleship and i was wondering how to write a section of code so that if you type the word 'quit' in the command window it terminates the whole program no matter what stage it is at,

i have tried this -

if quit
        
    disp ('end game')
        
    end

but it does not work and is showing errors when i try ot use it

[Voss]

quit = strcmp(input('Quit?','s'),'quit');
if quit
    disp ('end game')
    % terminate the game somehow
end