How to add custom keyboard layout on Linux

I accidentally ᚦᛖ᛫ᚱᚢᚾᛖᛋ

Recently on Fediverse I stumbled upon someone with runic username. Quick check - and, turns out, runes are part of Unicode since 1999! Also, Wikipedia has a whole article dedicated to runes in J.R.R. Tolkien's works, including a subsection about runes from "The Hobbit" - the ones that I learned by heart back in childhood¹.

Could I add them as a custom keyboard layout to my Linux machine?

Somewhere on Internet I've heard that it's quite easy!

Just have a look at the file /usr/share/X11/xkb/symbols/latin - it has lines like this:

key <AD01>  { [         q,          Q,           at,  Greek_OMEGA ] };

They, basically, mean that pressing key <AD01> should produce lowercase q character, or uppercase Q character when pressed together with Shift key, or @ symbol when pressed together with right Alt key, or Greek Omega character Ω when pressed together with both Shift and Alt keys². Note that you can use any Unicode character there, just by typing U1234.

Also note that on recent systems, for your custom keyboard layout to be picked up by GUI tools, it's enough just to save it to the /usr/share/X11/xkb/symbols/custom file.

Result

And here is my layout:

default partial alphanumeric_keys
xkb_symbols "hobbitrunes" {

    name[Group1]="Hobbit runes";
    include "level3(ralt_switch)"

    key <AD02>  {[ U16B9 ]}; // w: ᚹ
    key <AD03>  {[ U16D6, U16DF, U16DF ]}; // e: ᛖ; shift+e=alt+e=ee: ᛟ
    key <AD04>  {[ U16B1 ]}; // r: ᚱ
    key <AD05>  {[ U16CF, U16A6, U16E5 ]}; // t: ᛏ: shift+t=th: ᚦ; alt+t=st: ᛥ
    key <AD06>  {[ U16A3 ]}; // y: ᚣ
    key <AD07>  {[ U16A2 ]}; // u: ᚢ
    key <AD08>  {[ U16C1 ]}; // i: ᛁ
    key <AD09>  {[ U16A9, U16F3, U16C7 ]}; // o: ᚩ; shift+o=oo: ᛳ; alt+o=oe: ᛇ
    key <AD10>  {[ U16C8 ]}; // p: ᛈ

    key <AC01>  {[ U16AB, U16AA, U16E0 ]}; // a: ᚫ; shift+a=ae: ᚪ; alt+a=ea: ᛠ
    key <AC02>  {[ U16CB, U16F2, U16E5 ]}; // s: ᛋ; shift+s=sh: ᛲ; alt+s=st: ᛥ
    key <AC03>  {[ U16DE ]}; // d: ᛞ
    key <AC04>  {[ U16A0 ]}; // f: ᚠ
    key <AC05>  {[ U16B7, U16DD, U16DD ]}; // g: ᚷ; shift+g=alt+g=ng: ᛝ
    key <AC06>  {[ U16BB ]}; // h: ᚻ
    key <AC07>  {[ U16C1 ]}; // j: ᛁ
    key <AC08>  {[ U16F1 ]}; // k: ᛱ
    key <AC09>  {[ U16DA ]}; // l: ᛚ

    key <AB01>  {[ U16E3 ]}; // z: ᛣ
    key <AB02>  {[ U16C9 ]}; // x: ᛉ
    key <AB03>  {[ U16B3 ]}; // c: ᚳ
    key <AB04>  {[ U16A2 ]}; // v: ᚢ
    key <AB05>  {[ U16D2 ]}; // b: ᛒ
    key <AB06>  {[ U16BE, U16DD, U16DD ]}; // n: ᚾ; shift+n=alt+n=ng: ᛝ
    key <AB07>  {[ U16D7 ]}; // m: ᛗ

};

If your system is, like mine, rather recent and equipped with GUI keyboard layout configuration, then you just need to save this to the /usr/share/X11/xkb/symbols/custom file, and then choose "A user-defined custom Layout" in your input languages selector.

Or, if you're using setxkbmap from the command line, then you can this to and (new) file inside the /usr/share/X11/xkb/symbols/ dir (for example, you can call it runes), and then use this filename as a language code when configuring setxkbmap - for example, like this:

setxkbmap us,runes

And then you, like me, ᚹᛁᛚᛚ᛫ᛒᛖ᛫ᚫᛒᛚᛖ᛫ᛏᚩ᛫ᚹᚱᛁᛏᛖ᛫ᚢᛋᛁᛝ᛫ᚦᛖ᛫ᚱᚢᚾᛖᛋ᛫ᚠᚱᚩᛗ᛭ᚦᛖ᛫ᚻᚩᛒᛒᛁᛏ᛭

Worth noting that these are likely not "the right" runes: these are not the ones which were used historically; they are not the ones used by (majority) of dwarfs in Middle earth. But they are the ones I learned back in childhood, so they're the ones I'm using.

Also, there is another keyboard layout, which you might or might not like better, and an online translator, which translates (most of) these runes back to latin (English) text.