Как установить новый (пользовательский) MIME-тип в моей системе Linux с помощью инструментов CLI?

Я начну с цитирования раздела ПРИМЕРЫ в man xdg-mime

EXAMPLES
           xdg-mime install shinythings-shiny.xml

       Adds a file type description for "shiny"-files. "shinythings-" is used as the vendor prefix. The file type description could look as follows.

           shinythings-shiny.xml:

           <?xml version="1.0"?>
           <mime-info xmlns='http://www.freedesktop.org/standards/shared-mime-info'>
             <mime-type type="text/x-shiny">
               <comment>Shiny new file type</comment>
               <glob pattern="*.shiny"/>
               <glob pattern="*.shi"/>
             </mime-type>
           </mime-info>

       An icon for this new file type must also be installed, for example with:

           xdg-icon-resource install --context mimetypes --size 64 shiny-file-icon.png text-x-shiny

I wish to understand both adding this mime association for 1) my user account as well as 2) system-wide.

С той же manстраницы

xdg-mime install [--mode mode] [--novendor] mimetypes-file
--mode mode

mode can be user or system. In user mode the file is (un)installed for the current user only. In system mode the file is (un)installed for all users on the system. Usually only root is allowed to install in system mode.
The default is to use system mode when called by root and to use user mode when called by a non-root user.

when including glob-deleteall in a user-local definition, it removes any existing system-wide mime associations

Да , glob -deleteall используется для перезаписи части glob определения MIME-типа, но не только системы -во всей системе. Оба в зависимости от режима

mentions the specific directories where things should be located on an Arch Linux system

системный режим будет установлен в /usr/share/mime/. режим пользователя от до .local/share/mimeи список файлов:

./.local/share/mime/generic-icons
./.local/share/mime/mime.cache
./.local/share/mime/types
./.local/share/mime/text
./.local/share/mime/text/x-shiny.xml
./.local/share/mime/version
./.local/share/mime/treemagic
./.local/share/mime/globs
./.local/share/mime/globs2
./.local/share/mime/aliases
./.local/share/mime/subclasses
./.local/share/mime/magic
./.local/share/mime/icons
./.local/share/mime/XMLnamespaces
./.local/share/mime/packages/shinythings-shiny.xml

Ведь беги

update-mime-database ~/.local/share/mime/

, чтобы активировать конфигурацию.