sudo apt install build-essential dkms linux-headers-$(uname -r)
sudo mount /dev/sr0 /media/cdrom
cd /media/cdrom
sudo ./VBoxLinuxAdditions.ru
sudo apt install build-essential dkms linux-headers-$(uname -r)
sudo mount /dev/sr0 /media/cdrom
cd /media/cdrom
sudo ./VBoxLinuxAdditions.ru
$ sudo locale-gen "en_US.UTF-8"
Generating locales...
en_US.UTF-8... done
Generation complete.
$ sudo dpkg-reconfigure locales
Generating locales...
en_US.UTF-8... up-to-date
Generation complete.
Source: command line – How do I fix my locale issue? – Ask Ubuntu
Server-Based VirtualBox
The Linux Kernel HOWTO
Source: The Linux Kernel HOWTO