How to check which Emacs I am using?

I have two Emacs (Aquamacs and text-based Emacs) on my Mac.

In my .emacs file, I can c开发者_StackOverflow社区heck if I'm using Aquamacs with ...

(boundp 'aquamacs-version)

How can I check if I'm using text based emacs?

EDIT

Jürgen Hötzel's answer works, but for text based emacs, using

(unless (null window-system) ...) 

is better as (window-system) is not defined.

---

M-x emacs-version

ad some more characters here......

Sorry, from .emacs, just call

(emacs-version)

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I know this question was answered a long time ago, but I found another answer by typing emacs --help. This gives a list of options in which you can find emacs --version.

In my case, emacs --version prints: GNU Emacs 24.3.1.

I have only tested this solution on Linux with my current version of Emacs. I do not know if the same solution applies to Windows, or to older versions of Emacs, but in theory it should.

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(if (window-system)
    "window-based"
  "text-based")

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Or, you could use this:

(if (or (eq window-system 'ns)
        (eq window-system 'mac))
    (message "hello, world!"))

It will only print "hello, world!" when you run a graphical Emacs in OS X.

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Errr... (not (boundp 'aquamacs-version)), perhaps?