Preparing an OS image for QEMU

1. Create an empty image with custom size (60 GB in the example): $ qemu-img create ubuntuimg 60G

2. Install the OS in the image: $ <qemu-ox>/x86_64-softmmu/qemu-system-x86_64 -hda ubuntuimg -cdrom ~/Downloads/ubuntu-17.10.1-server-amd64.iso -m 8G -smp 4 -boot d

Note: If you do not have a graphic interface (for instance, if you are connected using SSH), use the options '-nographic' and '-device sga' to get the QEMU output in the console. You can also use '-curses' option instead.