/usr/bin/exmenen is in extra-xdg-menus 1.0-4.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | #!/bin/sh -e
EXTRAMENUDIR='/usr/share/extra-xdg-menus'
SYSTEMMENUDIR='/etc/xdg/menus/applications-merged'
if [ "x${XDG_CONFIG_HOME}" = "x" ]; then
  XDG_CONFIG_HOME="${HOME}/.config"
fi
HOMEMENUDIR="${XDG_CONFIG_HOME}/menus/applications-merged"
case $1 in
    --system)
        echo "Configuring extra menus: system wide"
	echo
        MENUDIR=${SYSTEMMENUDIR}
        ;;
    --local)
        echo "Configuring extra menus: local user"
	echo
        MENUDIR=${HOMEMENUDIR}
        ;;
    *)
        echo "Usage: exmenen (--system | --local) [<menu-name>]"
        exit 1
esac
if [ -z $2 ]; then
    echo "Which extra menu would you like to enable?"
    echo -n "Your choices are: "
    ls $EXTRAMENUDIR/*.menu | \
    sed -e "s,$EXTRAMENUDIR/,,g" | sed -e 's/\.menu$//g;' | xargs echo
    echo -n "Extra menu name? "
    read MENUNAME
else
    MENUNAME=$2
fi
if [ -e $MENUDIR/$MENUNAME.menu ]; then
    echo "This extra menu is already enabled!"
    exit 0
fi
if ! [ -e $EXTRAMENUDIR/$MENUNAME.menu ]; then
    echo "This extra menu does not exist!" >&2
    exit 1
fi
mkdir -p -m 0700 $MENUDIR
ln -sf "$EXTRAMENUDIR/$MENUNAME.menu" "$MENUDIR/$MENUNAME.menu";
echo "Extra menu $MENUNAME installed"
 |