Staffan:
> [Alt Gr] [o] [a] should work.
> http://stefaanlippens.net/accented-characters-on-qwerty-keyboard/
...
> 2018-03-30 15:08 GMT+02:00 Helio Loureiro <he...@loureiro.eng.br>:
...
> > Does anybody know how to create the "å" using or composition keys or <Alt>
> > on Linux em general?

If Staffans method didn't work/apply...

If you use the older method of xmodmap, you can check if it know about 
it. In my case å is altgr-e:
$ xmodmap -pke | grep  -i aring
keycode  26 = e E aring Aring

 I don't know much about the newer xkb method, but here is what I
figured out. Check if you have it configured like
  grep Xkb /etc/X11/xorg.conf /etc/X11/xorg.conf.d/*
or check the xserver current setting with
 setxkbmap -print
or
 xprop -root | grep XKB

E.g. here is what I get if I manually set xkb:

$ setxkbmap -rules xorg -model pc105 -layout us 
$ xprop -root | grep XKB
CUT_BUFFER0(STRING) = "xprop -root | grep XKB"
_XKB_RULES_NAMES(STRING) = "xorg", "pc105", "us", "", ""
$ setxkbmap -print
xkb_keymap {
        xkb_keycodes  { include "xfree86+aliases(qwerty)"       };
        xkb_types     { include "complete"      };
        xkb_compat    { include "complete"      };
        xkb_symbols   { include "pc+us+inet(pc105)"     };
        xkb_geometry  { include "pc(pc105)"     };
};

Then look into the dirs. of /usr/share/X11/xkb for matching files:
        xkb_keycodes  { include "xfree86+aliases(qwerty)"       };
is xkb_<directory> { include "<file>..." },i.e. 
 /usr/share/X11/xkb/keycodes/xfree86 and 
 /usr/share/X11/xkb/keycodes/aliases
etc. I would start with the files in the symbols directory, in my
case the file pc, us, and inet to see if I can find any info about
composing keys or the aring symbol. You would probably need to read
a lot from the links provided by https://www.x.org/wiki/XKB/ if you
want to to understand thoose files.

Hälsningar,
/Karl Hammar

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