I want to change a keyboard setup. But not in a "keyswapping" fashion, with Xmodmap or so, but rather change a default keymap (like EN_US, ...).
Right now i'm trying to use a Romanian keyboard which has Alt Right as the mode switcher (when I press it together with a for example, I get ă).
I want to be able to use Alt Left for this. That's all I want to know. Maybe it still has something to do with Xmodmap? Gnome supposedly overwrites Xmodmap, so there must be another way.

Where does X hold its keymappings?

Despite what you say, it sounds like all you want to do is swap Left-Alt with Right-Alt

1) You make your changes in /etc/X11/xkb/keycodes/xfree86 (even if you are running xorg)

2) Remember the constant on the LEFT is what to change (e.g. <DELE>)

3) First fire up xev and look for the key codes. On my system, Left ALT emits a 64 (which is assigned to <LALT>) and Right Alt emits a 113 (<RALT>). To swap these:

4) change <LALT>=64; to this: <RALT>=64;

5) change <RALT>=113; to this: <LALT>=113;

6) and comment out any duplicate definitions.


Log out and log in and it should work!

Thanks for the tip. The next thing I've got to find out is how to tell X, independantly of Gnome or other programs, which keymap I want.
Right now I'm using a so called "Romania US keyboard with Romanian letters".


This I must know because I'm going to get rid of Gnome soon, and I'll have more exotic setups like Xfce, Rox, FVWM, E17. And these don't follow the same guidelines (or at least don't have GUI's for everything).

Edit:
I believe I've found it.
For those wanting to know, it's most likely one of: /etc/X11/xkb/keymap/xfree86 or xfree98, and the exact keymap is either ro or ro_microsoft.