Linux – AltGr doesn’t work in Linux console

1. Using dmesg

One method would be to do so using dmesg:

   -n, --console-level level
          Set the level at which logging of messages is done to the console.  
          The level is a level number or abbreviation of the  level  name.
          For all supported levels see dmesg --help output.

For example:

$ sudo dmesg -n0

2. Using rsyslog

Another method would be through rsyslog. The config file /etc/rsyslog.conf:

#kern.*                                                 /dev/console

Changing this line to this:

kern.*                                                 /dev/null

NOTE: A restart of rsyslog is necessary, sudo service rsyslog restart.

3. Using sysctl

Lastly you can control this at the kernel level via sysctl.

I suggest you alter your /etc/sysctl.conf. Specifically, you want to tweak the kernel.printk line.

# Uncomment the following to stop low-level messages on console
kernel.printk = 3 4 1 3

You can see your current settings:

$ sudo sysctl -a|grep "kernel.printk\b"
kernel.printk = 4   4   1   7

4. Using silent

If you truly want to disable all logging, even during boot then change the string quiet to silent in the boot arguments to the kernel in GRUB, in /boot/grub2/grub.cfg.

linux   /vmlinuz-3.12.11-201.fc19.x86_64 ... rhgb silent ....

The problem is that when you use a common modifier like AltGr, programs actually see it as being pressed when you use the AltGr arrows. So Shift + AltGr + i actually appears to a program as if you are pressing Shift + Alt + Up and it's the addition of the extra Alt that confuses the program. You can avoid this by either adding more shortcuts to the program if possible, so Shift + Alt + Up does the same action as Shift + Up, or you can use an uncommon modifier that the program is not aware of.

There are other ways of doing this, but this was one of the simpler ways and works well for me. It creates a "Group2" overlay on the alphanumeric keys, such that when you switch to Group2 you will have arrows there instead of letters. You can switch to Group2 with a toggle (on/off like Caps Lock normally works) or a momentary (press to activate, like Shift normally works)

partial alphanumeric_keys
xkb_symbols "alpha_arrows" {
    key <AD07> {
        symbols[Group2]= [            Home ]  # u
    };
    key <AD08> {
        symbols[Group2]= [              Up ]  # i
    };
    key <AD09> {
        symbols[Group2]= [             End ]  # o
    };
    key <AD10> {
        symbols[Group2]= [           Prior ]  # p
    };
    key <AC07> {
        symbols[Group2]= [            Left ]  # j
    };
    key <AC08> {
        symbols[Group2]= [            Down ]  # k
    };
    key <AC09> {
        symbols[Group2]= [           Right ]  # l
    };
    key <AC10> {
        symbols[Group2]= [            Next ]  # ;
    };
    key <AB06> {
        symbols[Group2]= [          Delete ]  # n
    };
};

You can then pick a key to use as a Group2 activation key. You can see all the options (if you don't want to roll your own) with this:

$ grep grp /usr/share/X11/xkb/rules/base.lst

Then pick an option, for example this one activates the arrows only while Caps Lock is being held. It also adds a new combination Alt + Caps Lock to actually switch caps lock on and off:

$ setxkbmap -option grp:caps_switch

You can add this into your Xorg config file to make the change permanent - there are plenty of guides online about how to do this.

Note that:

• key is used, as opposed to replace key because we want to add to the existing definition, not replace it.
• If you actually have an alternate keyboard layout (possibly some international keyboards that can also type Latin/English letters), this method may not work for you. You will have to define a new type based on ALPHANUMERIC with extended modifiers (e.g. Hyper) to activate the arrow keys.