Installing the Guest Operating System

VirtualBox creates “guest” machines that run on top of a “host” machine. The host machine is the machine running VirtualBox. It “hosts” various virtual machines running as “guests” inside of VirtualBox. Once you define a virtual machine, you install an operating system, much like you would if you were installing a real operating system on your computer. Let’s install Ubuntu on this machine using the disk image you downloaded.

When you first start your virtual machine, VirtualBox detects that there’s no operating system and prompts you to install one. To start the machine, select your Ubuntu virtual machine from the list of machines and press the green Start button at the top of the VirtualBox interface.

VirtualBox prompts you for a virtual disk or optical disk that holds the installation media. Select the folder icon at the bottom right to open a file dialog. Navigate to your Downloads folder and select the Ubuntu ISO file you downloaded. Once you’ve selected the installation media, press the Start button.

The machine boots, and the Ubuntu installation program starts, displaying a welcome screen. Choose the Install Ubuntu option on the Welcome screen.

You’ll be prompted to select your keyboard layout from the list. Click Continue once you’ve made your selection.

The installer asks you if you’d like to do a normal installation or a minimal installation. Do a minimal installation, as you can install other things later if you decide you want them. It’ll also ask if you’d like to download updates and install third-party software during the installation. Installing updates during the installation can prevent some incompatibility issues between Ubuntu and VirtualBox. The third-party software option tells the installer to include packages that have additional restrictive licensing terms, such as Flash and MP3 support.

On the Installation Type screen, you will see this screen, asking you to erase your disk.

Don’t worry, you won’t be erasing your actual computer’s hard disk. You’re just erasing the already blank virtual disk you created for your Ubuntu virtual machine. The virtual disk you created doesn’t have a filesystem on it, and Ubuntu needs to format the disk so it can add one.

Select the Erase disk option and click the Install Now button to continue.

You’ll see a confirmation box telling you that the installer will create two partitions on the disk. The first partition is the main storage partition which will hold your operating system files and data. The second partition is the swap partition, a special partition Linux systems use as temporary memory in case you run out of RAM.

Click Continue to start the installation process. While the files copy, you’ll see a few additional prompts.

The first asks for your time zone. Select your time zone on the map and press Continue.

Next, the installation prompts you to create a user and name the computer as shown in the figure. This creates the user account you’ll use to log in to Ubuntu.

Choose a password that you’ll remember, and choose whether you want to require the password to log in to the machine, then press Continue. The installer copies the rest of the operating system files. Once it’s done, click the Restart Now button to restart the virtual machine.

The screen will display a message asking you to remove the installation disk. If you don’t, the installation will start over when you reboot. In many cases, VirtualBox will do this for you, but double-check this by clicking the Devices menu in VirtualBox, selecting Optical Drives, and then clicking Remove Disk from Virtual Drive. Press Enter to continue, and the virtual machine will reboot.

Locating the Devices Menu
	On macOS, VirtualBox uses a unified menu at the top of the screen like other macOS applications. You’ll find the Devices menu and other options in that menu when your virtual machine has focus. On Windows, you’ll find the Devices menu entry at the top of the virtual machine window itself, instead of on the VirtualBox window where you create and manage machines.

Once the machine restarts, Ubuntu loads, and you’re presented with a login screen. But before you log in, let’s create a snapshot so you can reset your machine if something goes wrong.