Enable the compose key

To enable the Compose key and configure a certain key on your keyboard as the Compose key, set the org.gnome.desktop.input-sources.xkb-options GSettings key. That way, the setting will be enabled by default for all users on your system.

Set the Right Alt key as the Compose key

  1. Create the user profile which contains the following lines:

    /etc/dconf/profile/user

    user-db:user
system-db:local

    local is the name of a dconf database.

  2. Create the directory /etc/dconf/db/local.d/ if it does not already exist.

  3. Create a local database for machine-wide settings in /etc/dconf/db/local.d/00-input-sources:

    [org/gnome/desktop/input-sources]
# Set the Right Alt key as the Compose key and enable it
xkb-options=['compose:ralt']

    If you want to set a different key than Right Alt, replace ralt with the name of that key as specified in the xkeyboard-config(7) man page, section Position of Compose key.

  4. Override the user's setting and prevent the user from changing it in /etc/dconf/db/local.d/locks/input-sources:

    # Lock the list of enabled XKB options
/org/gnome/desktop/input-sources/xkb-options

  5. Update the system databases:

    # dconf update

  6. Users must log out and back in again before the system-wide settings take effect.