What are the meta, super, and hyper keys?
In System -> Preferences -> Keyboard -> Layout -> Options ->Alt/Win key behavior
What do meta, super, hyper mean?
Meta, Super and Hyper are modifier keys that modify the key's function. They are specific to the Symbolics Space Cadet Keyboard used on Lisp machines back in the day. Their function is sometimes emulated using other keys.
The Meta key is not found on modern keyboards. Its use is sometimes emulated with AltGr (on some international layouts) or the right Alt key on the others. In addition:
- Sun keyboards have a meta key (◆) as well
- Emacs calls Esc the Meta key
The Super key is equivalent to or the ⌘ (command) key. In Ubuntu, it's just another name for .
Hyper is the fourth (counting Ctrl) and last modifier on the Space cadet keyboard. In Ubuntu, its function is undefined (I think), but it can be mapped, as in the screen shot above, to , should it be needed.
Note that GNOME and X.org implement many modifiers. Meta, Super and Hyper are not Linux's way of dealing with any modifier keys, but merely three of them specific to the Space Cadet keyboard. There is also Menu, Compose, AltGr, Greek, Front, X and others.
However, by convention the Windows logo key is called Super, and it is not implemented as yet another modifier by X.org.
Furthermore, the definition of modifier keys depends on:
The keyboard itself
The keyboard layout
The operating system's implementation
It's therefore almost impossible to generalise this information. I've tried to be somewhat specific to Gnome/X.org using a Windows-style keyboard with one of the more popular layouts. To test your keyboard, you can run
xev- its terminal output will tell you what modifiers have been detected for your keyboard.
The Macintosh keyboard has a completely different set of modifiers
Some additional information:
The Windows key is also sometimes called Meta. E.g. in KDE.
The Alt key is sometimes called Option, as this is its equivalent on Macintosh keyboards
The Compose key (not a modifier, but a dead key), also called Multi, is often mapped to the Menu key or the right Windows key.
The AltGr key I've mentioned is also called a third-level modifier. Each key on the keyboard has, potentially, four characters on it. The first level is the lowercase, then it goes uppercase, Alt + something, and Alt + Shift + something. For example, the four glyphs on my A key are a, A, æ and Æ.
It's all a mess :-)
As they've been addressed in the comments:
The Fn is not really comparable. It's a hardware key that's not directly interfaceable by the operating systems. Pressing Fn and another key causes an entirely different code to be sent to the operating system. Examples for this include XF86AudioMute, XF86Eject and so on. The Operating system can't detect whether fn is pressed or not.
The SysRq key is traditionally a label on the Print Screen key indicating its function if used with the modifier Alt. It is sometimes, especially on newer notebooks, mapped to Fn+Alt+Print. In Linux, it provides a few Magic shortcuts.
"Wikipedia claims the Windows key is sometimes called Meta, I didn't find any other reference for this." From Ubuntu11.04's help, it says: "What is the "meta" key? The the meta key is key between the Ctrl and Alt keys on your keyboard. It may sometimes be called the windows key, logo key, system key, or even the Ubuntu key. If you have an Apple keyboard, there will not be a meta key on your keyboard. The Command (Cmd) key can be used instead. The meta key serves a special function in Unity. If you press the meta key, the Dash is displayed. If you press and hold the meta key, the Launcher will
I have Ubuntu with both Unity and KDE, while Unity calls it Super (hold it down in 12.04 to see a quick command reference), KDE calls it Meta... >.<
@m93a the f-lock one is easy: just turn it on and ignore it exists. If you have trouble, ckeck it's on, then promptly forget about it again.
@badp I don't have it on my kbd, just seems like an interesting key to talk about :) I'd like to have one of that super-old keyboard at home...
For me, with all modern keyboards, computers, and Linux distro's, Meta and Super has always been different names for the same key, namely the "Windows" key.
It looks like nobody quite remembers what these keys were for. (: http://home.comcast.net/~mmcm/kbd/SpaceCadet.html
About the Meta key, it seems to me it's the *left* alt key. I don't see how AltGr could be used for anything else than entering other levels of characters.
As regards Meta, why do you mention _right_ ALT and for international layouts ALTGR _only_? At least on US/UK keyboard the Meta can be both the left or right ALT. For international layouts the Meta can be the ALTGR replacing the right ALT, as you say, but also the left ALT.
Technically Mac's can't detect if fn is pressed and remap it but that isn't the norm.
As put in the comments above, under KDE (Fedora in my case), the "meta" Key is the Windows key. And it is assigned to certain shortcuts by default (meta + tab for switching activities, for example). Someone with enough rep could edit the answer to include this information, since it is mostly complete, but lacking this essential bit.
I can detect Fn on my ThinkPad X390. I don't recall which keycode it sends, but some machines do actually send a code when pressing it. I have thought about binding shortcuts to it but haven't gotten that far yet.