Exit the current Octave session. If the optional integer value
status is supplied, pass that value to the operating system as the
Octave's exit status. The default value is zero.
— Built-in Function: atexit (fcn)
Register a function to be called when Octave exits. For example,
function bye_bye ()
disp ("Bye bye");
endfunction
atexit ("bye_bye");
will print the message "Bye bye" when Octave exits.