KVM

Creating a disk image for the guest/usr/local/kvm/bin/qemu-img create -f qcow2 vdisk.img 10G

Installing a guest operating systemsudo /usr/local/kvm/bin/qemu-system-x86_64 -hda vdisk.img -cdrom /path/to/boot-media.iso \ -boot d -m 384.

If have Error 'Could not access KVM kernel module: No such file or directory failed to initialize KVM: No such file or directory 
No accelerator found! ', please exe modprobe kvm-intel or kvm-amd. And make sure you have vt/svm capable CPU AND bios that support it.

Running the newly-installed guestsudo /usr/local/kvm/bin/qemu-system-x86_64 vdisk.img -m 384

or a slightly more complicated example, where it is assumed that bridged networking is available on tap0; see ["Kernel-optimizations"] for some setup hints:

/usr/local/kvm/bin/qemu-system-x86_64 -hda xp-curr.img -m 512 -soundhw es1370 -no-acpi -snapshot -localtime -boot c -usb -usbdevice tablet -net nic,vlan=0,macaddr=00:00:10:52:37:48 -net tap,vlan=0,ifname=tap0,script=no

(kvm doesn't make a distinction between i386 and x86_64 so even in i386 you should use `qemu-system-x86_64`)

If you're on Debian Etch, substitute `kvm` for `qemu-system-x86_64` (thanks to fromport, soren and mael_). See also the entries under the label "Ubuntu" on the page. qemu-system-x86_64`

If you're on Fedora/RHEL/CentOS (and installed a kvm package and not built kvm yourself from source) then substitute qemu-kvm for qemu-system-x86_64