| Name | Last modified | Size | Description | |
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| modules/ | 2023-12-04 01:48 | - | ||
This FAQ/HOWTO is about the Linux keyboard and console, not about X, which substitutes its own handling. However, it seems useful to document some of the Linux keyboard and console related properties of X.
First of all, when X is started (say using startx or xinit)
it opens the first unused console, unless the desired console has been
indicated explicitly, as in xinit -- vt12.
Note that this will fail when there is no device file /dev/tty12,
but that it will not fail when the indicated console was in use already.
When X finishes, it will return to the original console.
While it is running one can use Ctrl-Alt-Fn to switch to VTn.
The XFree86 keymap mechanism is much poorer than the Linux mechanism.
For each keycode there are at most 4 symbols defined, namely for the
4 keymaps plain, shift, mod, mod+shift. What is the modifier mod?
It is the one designated by the symbol Mode_switch.
For example, the command xmodmap keys.dk, where the file
keys.dk contains
keycode 64 = Mode_switch
keycode 113 = Mode_switch
keycode 38 = a A aring Aring
keycode 26 = e E ae AE
keycode 32 = o O oslash Ooblique
xmodmap command can be placed in the .xinitrc
shell script that is executed by default when X is started.
Since version 2.1, XFree86 will initialize its keymap from the Linux keymap, as far as possible. However, Linux had 16 entries per key (one for each combination of the Shift, AltGr, Ctrl, Alt modifiers) and presently has 256 entries per key, while X has 4 entries per key (one for each combination of Shift, Mod), so some information is necessarily lost.
First X reads the Xconfig file, where definitions of the LeftAlt, RightAlt,
RightCtl, ScrollLock keys as Meta, ModeShift, Compose, ModeLock or ScrollLock
might be found - see X386keybd(1), later XFree86kbd(1).
For Mod the LeftAlt key is taken, unless RightCtl was defined as ModeShift or ModeLock, in which case RightCtl is taken, or RightAlt was so defined, in which case RightAlt is taken. This determi