exit

Python

面白いなぁ。ちなみに実装は lib/site.py にある。
Python 2.4 の場合

def setquit():
    """Define new built-ins 'quit' and 'exit'.
    These are simply strings that display a hint on how to exit.

    """
    if os.sep == ':':
        exit = 'Use Cmd-Q to quit.'
    elif os.sep == '\\':
        exit = 'Use Ctrl-Z plus Return to exit.'
    else:
        exit = 'Use Ctrl-D (i.e. EOF) to exit.'
    __builtin__.quit = __builtin__.exit = exit

Python 2.5 の場合

def setquit():
    """Define new built-ins 'quit' and 'exit'.
    These are simply strings that display a hint on how to exit.

    """
    if os.sep == ':':
        eof = 'Cmd-Q'
    elif os.sep == '\\':
        eof = 'Ctrl-Z plus Return'
    else:
        eof = 'Ctrl-D (i.e. EOF)'

    class Quitter(object):
        def __init__(self, name):
            self.name = name
        def __repr__(self):
            return 'Use %s() or %s to exit' % (self.name, eof)
        def __call__(self, code=None):
            # Shells like IDLE catch the SystemExit, but listen when their
            # stdin wrapper is closed.
            try:
                sys.stdin.close()
            except:
                pass
            raise SystemExit(code)
    __builtin__.quit = Quitter('quit')
    __builtin__.exit = Quitter('exit')