How to install Virtualbox extension pack on Linux host by CLI

1. Install Virtualbox
2. Download extension pack (for the installed version of Virtualbox)
3. Make VM (in my case - Ubuntu LTS server)
4. From VM menu:
   - Devices -> Insert Guest Addition CD Image
5. If it does error, do this in Guest System:
   sudo apt install build-essential dkms
6. Do this:
   mount /dev/cdrom /mnt
   cd /mnt
   sudo ./VBoxLinuxAdditions.run
   reboot
7. cd
8. umount /mnt
9. Devices -> Optical Drive -> Remove disk from optical drive
10. Remove Extension Pack from Host system:
    rm ~/.config/VirtualBox/VboxGuestAdditions_XX.iso
11. Remove Guest Additions:
    cd /opt//
    sudo ./uninstall.sh