The desktop file ID is the identifier of an installed desktop entry file.
To determine the ID of a desktop file, make its full path relative to
$XDG_DATA_DIRS component in which the desktop file is installed, remove the "applications/"
prefix, and turn '/' into '-'.
the desktop file ID
If multiple files have the same desktop file ID, the first one in the $XDG_DATA_DIRS precedence order is used.
For example, if
$XDG_DATA_DIRS contains the default paths /usr/local/share:/usr/share, then
/usr/share/applications/org.foo.bar.desktop both have
the same desktop file ID
org.foo.bar.desktop, but only the first
one will be used.
it is undefined which is selected.
If the desktop file is not installed in an
applications subdirectory of one
of the $XDG_DATA_DIRS components, it does not have an ID.