To start a virtual machine, you have several options:
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Double-click on its entry in the list within the Manager window or
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select its entry in the list in the Manager window it and press the "Start" button at the top or
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for virtual machines created with VirtualBox 4.0 or later, navigate to the "VirtualBox VMs" folder in your system user's home directory, find the subdirectory of the machine you want to start and double-click on the machine settings file (with a
.vboxfile extension).
This opens up a new window, and the virtual machine which you selected will boot up. Everything which would normally be seen on the virtual system's monitor is shown in the window, as can be seen with the image in Section 1.2, “Some terminology”.
In general, you can use the virtual machine much like you would use a real computer. There are couple of points worth mentioning however.
When a VM gets started for the first time, another wizard -- the "First Start Wizard" -- will pop up to help you select an installation medium. Since the VM is created empty, it would otherwise behave just like a real computer with no operating system installed: it will do nothing and display an error message that no bootable operating system was found.
For this reason, the wizard helps you select a medium to install an operating system from.
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If you have physical CD or DVD media from which you want to install your guest operating system (e.g. in the case of a Windows installation CD or DVD), put the media into your host's CD or DVD drive.
Then, in the wizard's drop-down list of installation media, select "Host drive" with the correct drive letter (or, in the case of a Linux host, device file). This will allow your VM to access the media in your host drive, and you can proceed to install from there.
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If you have downloaded installation media from the Internet in the form of an ISO image file (most probably in the case of a Linux distribution), you would normally burn this file to an empty CD or DVD and proceed as just described. With VirtualBox however, you can skip this step and mount the ISO file directly. VirtualBox will then present this file as a CD or DVD-ROM drive to the virtual machine, much like it does with virtual hard disk images.
For this case, the wizard's drop-down list contains a list of installation media that were previously used with VirtualBox.
If your medium is not in the list (especially if you are using VirtualBox for the first time), select the small folder icon next to the drop-down list to bring up a standard file dialog, with which you can pick the image file on your host disks.
In both cases, after making the choices in the wizard, you will be able to install your operating system.
As of version 3.2, VirtualBox provides a virtual USB tablet device to new virtual machines through which mouse events are communicated to the guest operating system. As a result, if you are running a modern guest operating system that can handle such devices, mouse support may work out of the box without the mouse being "captured" as described below; see Section 3.5.1, “"Motherboard" tab” for more information.
Otherwise, if the virtual machine only sees standard PS/2 mouse and keyboard devices, since the operating system in the virtual machine does not "know" that it is not running on a real computer, it expects to have exclusive control over your keyboard and mouse. This is, however, not the case since, unless you are running the VM in full screen mode, your VM needs to share keyboard and mouse with other applications and possibly other VMs on your host.
As a result, initially after installing a guest operating system and before you install the Guest Additions (we will explain this in a minute), only one of the two -- your VM or the rest of your computer -- can "own" the keyboard and the mouse. You will see a second mouse pointer which will always be confined to the limits of the VM window. Basically, you activate the VM by clicking inside it.
To return ownership of keyboard and mouse to your host operating system, VirtualBox reserves a special key on your keyboard for itself: the "host key". By default, this is the right Control key on your keyboard; on a Mac host, the default host key is the left Command key. You can change this default in the VirtualBox Global Settings, see Section 1.15, “Global Settings”. In any case, the current setting for the host key is always displayed at the bottom right of your VM window, should you have forgotten about it:
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In detail, all this translates into the following:
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Your keyboard is owned by the VM if the VM window on your host desktop has the keyboard focus (and then, if you have many windows open in your guest operating system as well, the window that has the focus in your VM). This means that if you want to type within your VM, click on the title bar of your VM window first.
To release keyboard ownership, press the Host key (as explained above, typically the right Control key).
Note that while the VM owns the keyboard, some key sequences (like Alt-Tab for example) will no longer be seen by the host, but will go to the guest instead. After you press the host key to re-enable the host keyboard, all key presses will go through the host again, so that sequences like Alt-Tab will no longer reach the guest. For technical reasons it may not be possible for the VM to get all keyboard input even when it does own the keyboard. Examples of this are the Ctrl-Alt-Del sequence on Windows hosts or single keys grabbed by other applications on X11 hosts like the GNOME desktop's "Control key highlights mouse pointer" functionality.
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Your mouse is owned by the VM only after you have clicked in the VM window. The host mouse pointer will disappear, and your mouse will drive the guest's pointer instead of your normal mouse pointer.
Note that mouse ownership is independent of that of the keyboard: even after you have clicked on a titlebar to be able to type into the VM window, your mouse is not necessarily owned by the VM yet.
To release ownership of your mouse by the VM, also press the Host key.
As this behavior can be inconvenient, VirtualBox provides a set of tools and device drivers for guest systems called the "VirtualBox Guest Additions" which make VM keyboard and mouse operation a lot more seamless. Most importantly, the Additions will get rid of the second "guest" mouse pointer and make your host mouse pointer work directly in the guest.
This will be described later in Chapter 4, Guest Additions.
Operating systems expect certain key combinations to initiate certain procedures. Some of these key combinations may be difficult to enter into a virtual machine, as there are three candidates as to who receives keyboard input: the host operating system, VirtualBox, or the guest operating system. Who of these three receives keypresses depends on a number of factors, including the key itself.
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Host operating systems reserve certain key combinations for themselves. For example, it is impossible to enter the Ctrl+Alt+Delete combination if you want to reboot the guest operating system in your virtual machine, because this key combination is usually hard-wired into the host OS (both Windows and Linux intercept this), and pressing this key combination will therefore reboot your host.
Also, on Linux and Solaris hosts, which use the X Window System, the key combination Ctrl+Alt+Backspace normally resets the X server (to restart the entire graphical user interface in case it got stuck). As the X server intercepts this combination, pressing it will usually restart your host graphical user interface (and kill all running programs, including VirtualBox, in the process).
Third, on Linux hosts supporting virtual terminals, the key combination Ctrl+Alt+Fx (where Fx is one of the function keys from F1 to F12) normally allows to switch between virtual terminals. As with Ctrl+Alt+Delete, these combinations are intercepted by the host operating system and therefore always switch terminals on the host.
If, instead, you want to send these key combinations to the guest operating system in the virtual machine, you will need to use one of the following methods:
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Use the items in the "Input" → "Keyboard" menu of the virtual machine window. There you will find "Insert Ctrl+Alt+Delete" and "Ctrl+Alt+Backspace"; the latter will only have an effect with Linux or Solaris guests, however.
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Press special key combinations with the Host key (normally the right Control key), which VirtualBox will then translate for the virtual machine:
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Host key + Del to send Ctrl+Alt+Del (to reboot the guest);
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Host key + Backspace to send Ctrl+Alt+Backspace (to restart the graphical user interface of a Linux or Solaris guest);
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Host key + F1 (or other function keys) to simulate Ctrl+Alt+F1 (or other function keys, i.e. to switch between virtual terminals in a Linux guest).
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For some other keyboard combinations such as Alt-Tab (to switch between open windows), VirtualBox allows you to configure whether these combinations will affect the host or the guest, if a virtual machine currently has the focus. This is a global setting for all virtual machines and can be found under "File" → "Preferences" → "Input" → "Auto-capture keyboard".
While a virtual machine is running, you can change removable media in the "Devices" menu of the VM's window. Here you can select in detail what VirtualBox presents to your VM as a CD, DVD, or floppy.
The settings are the same as would be available for the VM in the "Settings" dialog of the VirtualBox main window, but since that dialog is disabled while the VM is in the "running" or "saved" state, this extra menu saves you from having to shut down and restart the VM every time you want to change media.
Hence, in the "Devices" menu, VirtualBox allows you to attach the host drive to the guest or select a floppy or DVD image using the Disk Image Manager, all as described in Section 1.11, “Virtual machine configuration”.
You can resize the virtual machine's window when it is running. In that case, one of three things will happen:
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If you have "scale mode" enabled, then the virtual machine's screen will be scaled to the size of the window. This can be useful if you have many machines running and want to have a look at one of them while it is running in the background. Alternatively, it might be useful to enlarge a window if the VM's output screen is very small, for example because you are running an old operating system in it.
To enable scale mode, press the host key + C, or select "Scale mode" from the "Machine" menu in the VM window. To leave scale mode, press the host key + C again.
The aspect ratio of the guest screen is preserved when resizing the window. To ignore the aspect ratio, press Shift during the resize operation.
Please see Chapter 14, Known limitations for additional remarks.
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If you have the Guest Additions installed and they support automatic resizing, the Guest Additions will automatically adjust the screen resolution of the guest operating system. For example, if you are running a Windows guest with a resolution of 1024x768 pixels and you then resize the VM window to make it 100 pixels wider, the Guest Additions will change the Windows display resolution to 1124x768.
Please see Chapter 4, Guest Additions for more information about the Guest Additions.
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Otherwise, if the window is bigger than the VM's screen, the screen will be centered. If it is smaller, then scroll bars will be added to the machine window.
When you click on the "Close" button of your virtual machine window (at the top right of the window, just like you would close any other window on your system), VirtualBox asks you whether you want to "save" or "power off" the VM. (As a shortcut, you can also press the Host key together with "Q".)
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The difference between these three options is crucial. They mean:
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Save the machine state: With this option, VirtualBox "freezes" the virtual machine by completely saving its state to your local disk.
When you start the VM again later, you will find that the VM continues exactly where it was left off. All your programs will still be open, and your computer resumes operation. Saving the state of a virtual machine is thus in some ways similar to suspending a laptop computer (e.g. by closing its lid).
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Send the shutdown signal. This will send an ACPI shutdown signal to the virtual machine, which has the same effect as if you had pressed the power button on a real computer. So long as the VM is running a fairly modern operating system, this should trigger a proper shutdown mechanism from within the VM.
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Power off the machine: With this option, VirtualBox also stops running the virtual machine, but without saving its state.
Warning
This is equivalent to pulling the power plug on a real computer without shutting it down properly. If you start the machine again after powering it off, your operating system will have to reboot completely and may begin a lengthy check of its (virtual) system disks. As a result, this should not normally be done, since it can potentially cause data loss or an inconsistent state of the guest system on disk.
As an exception, if your virtual machine has any snapshots (see the next chapter), you can use this option to quickly restore the current snapshot of the virtual machine. In that case, powering off the machine will not disrupt its state, but any changes made since that snapshot was taken will be lost.
The "Discard" button in the VirtualBox Manager window discards a virtual machine's saved state. This has the same effect as powering it off, and the same warnings apply.